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1
Kalifa, Ali. "Salt stress, and phosphorus absorption by potato plants cv. 'Russet Burbank'". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq29727.pdf.
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2
Attumi, Al-Arbe. "Effect of salt stress on phosphorus and sodium absorptions by soybean plants". Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=20242.
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The radiotracer methodology was combined with the Hoagland solution culture of growing soybean in a greenhouse to investigate the absorptions of phosphorus (P), calcium (Ca), and sodium (Na) as a function of salinity. Salt stress was varied by using zero to 120 mM NaCl. The research was initiated because of a need to increase soybean production in the saline soils of the semi-arid regions of the world. Although P absorption increased with time at each concentration of NaCl, increasing its concentrations ([NaCl]) to 120 mM reduced P uptake considerably. The addition of inorganic P (Pi) to the salt medium improved P absorption significantly (P < 0.0001) in stem, petiole, and roots. Polynomial regressions showed the relationship between 22Na activity and [NaCl] for leaves and petiole to be cubic (R2 = 1) while in the stem a quadratic relationship prevailed. A maximum of P and Na absorption was observed at 40 mM NaCl. The relationship between 32P activity and increasing [NaCl] was linear for the roots (a positive slope) and the stem (a negative slope). 45Ca and 32P dual labelling part of the experiments failed to produce results because an unexpectedly high degree of tissue quenching which prevented from obtaining the minimum counting requirements for separation. Shoot fresh and dry weights decreased linearly with increasing [NaCl] as did the root fresh and dry weights. Leaf chlorophyll content during the last week of the final harvest showed a linear relationship with time. Chlorophyll increased with time linearly when the growth medium contained zero and 40 mM NaCl; whereas a negative slope was obtained for 80 and 120 mM NaCl. It seems that P fertilization of the soil could ameliorate the salt effect. 22 Na uptake results indicated that there is a mechanism for exclusion of Na from soybean plant parts.
3
Zhou, Maoqian 1961. "Nitrogen fixation by alfalfa as affected by salt stress and nitrogen levels". Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277231.
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The growth and Nitrogen fixation by one low salt tolerant alfalfa (Medicago sativa L.) and two germination salt tolerant selections inoculated with were investigated at two salt levels (0, -0.6 Mpa) and two N rates (1, 5ppm) using a system which automatically recirculates a nutrient solution. The high level of salinity (-0.6 Mpa osmotic potential of culture solution) resulted in substantial reduction in the N fixation percentage and total fixed N. The effect of salinity was more pronounced for later cuttings than for the earlier cutting. The N fixation percentages were substantially decreased by increasing N level and the reduction was enhanced by time. The N treatment levels did not exhibit a significant effect on total fixed N. Cultivars did not differ in either growth or N fixation. However, the interaction of N and salinity significantly decreased the percentage and amount of N fixation.
4
Collins, R. P. "The role of calcium and potassium in salinity tolerance in Brassica rapa L. cv. RCBr seed". Thesis, Coventry University, 2012. http://curve.coventry.ac.uk/open/items/e0d653ff-7d6b-4827-9467-dc8bcb6ff621/1.
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The possibility of manipulating calcium (Ca2+) and potassium (K+) levels in seeds of Brassica rapa by altering parent plant nutrition and investigating the potential for increased salinity tolerance during germination, given that considerable amounts of literature imply that greater amounts of available exogenous Ca2+ and K+ can ameliorate the effects of salinity on both whole plant growth and germination, was evaluated. The investigation consisted of four growth trials. Two preliminary growth trials suggested that seed ion manipulation was possible without affecting the overall growth and vigour of the plant. After developing suitable high and low Ca2+ and K+ nutrient solutions for growth, a trial was carried out in a growth room and greenhouse, with various substrates and the seed of a certain size category was collected for subsequent ion and salinity tolerance analysis. Seed Ca2+ and K+ was significantly affected by growth substrate and nutrient solution and data showed that a significant negative regression relationship existed between seed Ca2+, K+ and Ca2+ + K+ levels and salinity tolerance. Further experimentation using hydroponic culture attempted to remove any possible effects of substrate and also to compare size categories of seed with a view to elucidating localisation of Ca2+ and K+. Seed Ca2+ was found to be significantly altered by nutrient solution in the two different sizes tested and higher Ca2+ nutrient solution was found to increase salinity tolerance in daughter seed. One significant negative regression correlation between salinity tolerance and seed K+ concentration existed in smaller seed, but disregarding seed size in a regression analysis of seed ion content and salinity tolerance, a significant negative relationship existed between seed Ca2+, K+ and Ca2++ K+. The results, especially in terms of Ca2+ nutrition, contradict much previous research that suggests increased salinity tolerance at germination can arise with the increased presence of Ca2+ and/or K+. Salinity tolerance was greater in seeds of larger size across all nutritional treatments and the smaller size range exhibited increased Ca2+ and K+ per μg seed. Ca2+ concentration in smaller seeds with greater surface area:volume ratios provided a clue to the potential localisation of Ca2+. Cross sectional staining showed that a greater proportion of seed Ca2+ may reside in the coat. This was confirmed by analysis which showed an approximate 50% split of total extractable seed Ca2+, regardless of size, between coat and embryo within a seed; the majority of which, per μg, resides in the coat. Further work looked at the relative solubility of the Ca2+ and K+ in these tissues and whole seed to look at the potential bioavailability of Ca2+ during germination from various parts of the seed. Most water soluble Ca2+ exists in the embryo and most insoluble Ca2+ exists in the coat, but coat Ca2+ was found to be ionically exchangeable and therefore bioavailable. K+ appeared mostly water soluble in embryo and coat. In line with previous whole plant research in this species, most Ca2+ is readily water soluble or ionically exchangeable in form and the possible negative effects of how increasing bioavailable Ca2+ may reduce salinity tolerance was discussed.
5
McKimmie, Timothy Irving 1948. "CHARACTERIZATION OF SALT TOLERANCE IN ALFALFA (MEDICAGO SATIVA L.)". Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/276348.
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Andrade, Maria Isabel. "PHYSIOLOGY OF SALT TOLERANCE IN GUAR, CYAMOPSIS TETRAGONOLOBA (L.) TAUB". Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275416.
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7
Zheng, Liansheng 1955. "Gene expression in two different genotypes of alfalfa under salt stressed and unstressed conditions". Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276936.
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Gene expression in two different genotypes of alfalfa, salt-tolerant and salt-sensitive, was examined by studying differences in protein products coded for by poly(A+) RNA isolated from shoot and root tissue. Plants were grown in hydroponics under unstressed or salt-stressed conditions. Two salinity levels (low salt: 30 mM NaCl and 6 mM CaCl2 and high salt: 133 mM NaCl and 27 mM CaCl2) and one unstressed control were applied. The salt-tolerant genotype showed higher biomass accumulation than the salt-sensitive genotype under both control and salt-stressed conditions. The difference in biomass accumulation between the two genotypes was greatest at the highest salt level. The effect of salt stress on gene expression was studied via in vitro translation of poly (A+) RNA with (35S) -methionine. The labeling pattern was similar in all treatments when analyzed by one dimensional SDS-PAGE. However, a two dimensional analysis (isoelectric focusing followed by SDS-PAGE) showed that salt-stress induced a number of new proteins and repressed several others.
8
Alm, David Michael. "Comparison and interaction of heat and salt stress in cultured tobacco cells". Virtual Press, 1986. http://liblink.bsu.edu/uhtbin/catkey/445616.
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Cultured tobacco cells (Nicotiana tabacum L., cv Wisconsin-38) were subjected to temporary sub-lethal heat and salt shock treatments to determine the effects of these treatments on various physiological parameters after subsequent lethal heat or salt stresses. Tobacco cells developed a tolerance to a non-permissive temperature stress (54C for 14 min) when pretreated with heat shock of 38C for 2h but not when pretreated at 42C for 2h. Cells pretreated at 38 (2h) exhibited less than 30% normal growth when the 54C stress came immediately after the 38C treatment. Tolerance to the 54C stress developed with increased interval between shock and stress with cells exhibiting 95% normal regrowth when the 54C stress was administered 8h after the 38C shock. The developement of heat tolerance was inhibited if heat shock was done in the presence of a non-injuring level of EGTA (.0.5mM). Cells treated with EGTA during heat shock grew normally at 23C but not after a 54C heat stress. EDTA (0.5mM) had little effect on the acquisition of tolerance to heat stress.Wisconsin-38 cells developed a tolerance to a non-permissive salt stress (2% NaCl for 16h) when pretreated at a lower salt level (1.2% NaCl) for 3h. Cells heat shocked at 38C exhibited increased tolerance of the lethal salt stress up to 8h. Conversely, cells heat shocked at 42C exhibited immediate tolerance to lethal salt stress and this tolerance decayed over eight hours. The heat shock-induced acquisition of salt tolerance was inhibited by both EGTA and EDTA.Proteins synthesized during heat and salt stress treatments were labeled with [35S]-methionine and/or [3H]-leucine and separated using Sodium dodecylsulfate polyacrylamide gel electrophoresis. Fluorographic analysis of the gels indicate that a number of proteins are produced in response to heat shock. Similar analysis of proteins from salt shocked cells indicates that no salt shock proteins are produced in response to a brief low-level sodium chloride shock.
9
El-Sheikh, Medhat. "Studies on the cellular and molecular basis of salt resistance in a halotolerant Arabidopsis thaliana cell line". Thesis, University of Glasgow, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274256.
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Robinson, David Lowell 1955. "RECURRENT SELECTION FOR GERMINATION SALT TOLERANCE IN ALFALFA (SALINITY, FORAGES, BREEDING)". Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/277015.
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LEDBETTER, CRAIG ALLEN. "HERITABILITY OF SALT TOLERANCE DURING GERMINATION AND EMERGENCE IN SHORT STAPLE COTTON (GOSSYPIUM HIRSUTUM L.)". Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183961.
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Soil salinity is a serious problem for farmers in irrigated agriculture. Soil salts cause reduced stands and yields because of toxic ion and osmotic problems for surviving seedlings. The tolerance to sodium chloride during germination and emergence was studied in three commercial cultivars of short staple cotton (Gossypium hirsutum L.). It is this stage of the life cycle that cotton is most sensitive to salts in the soil solution. The objectives of this study were to increase the tolerance to sodium chloride during germination and emergence and to determine the narrow sense heritability of this factor. Parental cultivars initially demonstrated 15% emergence at -1.2 MPa NaCl. Surviving salt tolerant plants were planted in the field and seeds from these plants were used as the germplasm for the next cycle of salt tolerance selection. Experiments were conducted to determine the relative salt tolerance of all plants at -1.2, -1.4, -1.6, and -1.8 MPa NaCl. Emergence of salt tolerant accessions from the first cycle of selection ranged from 3.1 to 25.8% in the first relative salt tolerance experiment. The average emergence of all accessions taken over all four salinity levels was 8.9% for first cycle plants. After a second cycle of selection for salt tolerance, the average emergence percentage increased to 13.0% over the four salinity levels. Emergence ranged from 0.7 to 32.6% in the second relative salt tolerance experiment. Narrow sense heritability of sodium chloride tolerance during germination and emergence was estimated at 0.38 using data from the first and second relative salt tolerance experiments.
12
Slail, Nabeel Younis 1963. "INFLUENCE OF SODIUM-CHLORIDE ON TRANSPIRATION AND PLANT GROWTH OF TWO TOMATO CULTIVARS". Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276516.
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Seedlings were grown at five salinity levels in Hoagland's solution for 4 weeks. Transpiration, leaf diffusive resistance, leaf temperature and plant growth of the tomato (Lycopersicon esculentum Mill.) cultivars 'VF 145B' and 'VF 10' were examined at different levels of NaCl ranging from 0 to -12 bars. Salinity-reduced transpiration increased leaf diffusive resistance and increased leaf temperature for both cultivars. Shoot length, root length, shoot and root weight and leaf area were all lower for the two cultivars at increasing salinity levels. However, the two cultivars responded differently to salinity, with VF 10 showing better growth at the control and the -4 bar treatment than VF 145 B. At -9 and -12 bar treatment, the reverse was true. Selection of tomato for salt resistance should not be based on vigorous growth at non-saline conditions because different genes may control the salt tolerance ability of the plants at high salinity levels.
13
Al-Rawahy, Salim Ali. "Nitrogen uptake, growth rate and yield of tomatoes under saline conditions". Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184894.
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Results of two studies are reported here, a greenhouse study and a field study. In the greenhouse study, dry matter yield and nitrogen (total and 15N) uptake of leaves, stems and roots of tomato plants (Lycopersicum esculentum Mill., cv. Columbia) subjected to saline stress by NaCl were studied. The integrated effects of responses of these tissues to salinity on the whole plant basis and levels of Na⁺, Cl⁻ and K⁺ accumulation in these tissues were also studied. The treatments consisted of low (control, 0.3 bar), medium (4.3 bars), and high (8.3 bars) salinity. The saline treatments were prepared by adding NaCl to nutrient solution in sand culture. The plants were 80 days old at the start of the treatments and each was in a pot containing 1.8 kg of quartz sand. The ¹⁵N was provided to plants by adding K¹⁵NO₃ to the pots and the 15N treatment continued with the saline treatments up to 30 days. The plants were harvested at each 5-day interval during the treatment period. Dry matter production and nitrogen (total and ¹⁵N) uptake were significantly lower for saline treatments as compared with the control. Differences in dry matter production and ¹⁵N uptake on whole plant basis appeared in the latter part of the treatment period between the two saline treatments. For most of the parameters studied, the leaves were found to be affected most by salinity, the roots were intermediate in their response and the stems were the least affected by salinity. The effect of salinity on the studied parameters were attributed to osmotic effects and specific ion effects of Na⁺ and/or Cl⁻. A field study with two cultivars--Columbia and Pearson was conducted at the Safford Agricultural Center. Three N treatments were used: 0 kg N/ha, 84 kg N/ha and 168 kg N/ha and two treatments consisting of two water sources--river water with an EC of 1.15 dS/m and more saline well water of EC of 2.21 dS/m. Columbia had a significantly higher yield of tomatoes than Pearson for both water types. The N treatments had no effect on tomato yield apparently due to high residual N remaining in the field from the previous crop. Commercially acceptable fresh market yields were approached with both varieties and waters in spite of moderate salinity and sodium under heavy textural soil conditions, high temperatures and the presence of certain diseases in the area.
14
Wang, Ding Xiang. "Interaction between the effects of sodium chloride and high temperature on the vegetative growth of tomato (Lycopersicon esculentum Mill.)". Title page, contents and summary only, 1993. http://web4.library.adelaide.edu.au/theses/09PH/09phw2456.pdf.
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Supriati, Rochmah. "The impact of salinity on root and leaf anatomy of hordeum jubatum L". Virtual Press, 1994. http://liblink.bsu.edu/uhtbin/catkey/902476.
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It had been generally accepted that salinity adversely affects the growth of plants. This study examined how the salinity level affects the growth of H. jubatum. A green house study was conducted to determine the effects of salinity levels on growth, and anatomy of root and leaf of H. jubatum. One week-old seedlings were transplanted and grown on 10-cm plastics pots filled with sand at Ball State University green house. Plants were subirrigated with hydroponic solution Dyna gro liquid 9-7-5 (NPK) and 0%, 0.5%, 1 %, and 1.5% NaCl for each treatment. The solutions were changed bi-weekly, evaporation losses were replaced daily. After aproximately 45 days, randomly chosen plants were harvested, washed, measured and weighted, to determine their growth such as: root biomass, shoot biomass, shoot height, leaf lenght, and leaf width. Slides of root and leave tissues were prepared with microtechnic standard using rotary microtome and N-butyl alcohol series. Anatomical variables measured included; root diameter, stele diameter, ratio of stele to root, thickness of leaf at mid vein, diameter of vb in mid vein, diameter of metaxylem in midvein, thickness of leaf at second lateral vein (left and right), diameter of vb at second lateral vein (left and right). The slides then were potoghraped with Olympus camera. Statistical analysis supported that salinity significantly affected the growth, morphology, and anatomy of H. jubatum.Department of Biology
16
Chen, Futai 1952. "Selection of asparagine substrate analog and sodium-chloride resistant mutants in Arabidopsis thaliana". Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276860.
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The inhibitory effects of NaCl, L- and D-asparagine, and asparagine substrate analogs, beta-aspartyl hydroxamate (AAH) and albizziin, alone or in combination on Columbia Arabidopsis seed germination and seedling survival were characterized under aseptic conditions. Germination on an agar medium supplemented with inorganic nutrients was prevented by 200 mM NaCl, 20 mM L-asparagine, 60 mM D-asparagine, 1.4 mM AAH, or 8 mM albizziin. Established seedlings were generally more tolerant to these chemicals than germinating seeds. Exogenous L- and D-asparagine partly reversed the inhibitory effects of NaCl on seed germination. L-asparagine also partly reversed AAH inhibition of germination. A M2 seed bank was created from the self-pollinated progeny of ethyl methane sulfonate treated seeds. Arabidopsis mutants having increased tolerance to NaCl and AAH, but not albizziin, were successfully selected from this seed bank.
17
Zegeer, Abreeza May 1956. "Interactions between saline stress and benzyladenine on chili peppers (Capsicum annuum L.)". Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277069.
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Exogenous application of BA (0, 50, 100 mg ul--1) had no significant effects on tolerance of chili peppers to salt (--0.75 MPa NaCl:CaCl₂, 3:1, w/w) as measured by vegetative and reproductive weights, numbers of reproductive structures, transpiration and total chlorophyll. When peppers were applied with microliter amounts of ¹⁴C labelled benzyladenine (BA; 44,400 dpm 1⁻¹), BA was translocated primarily acropetally from the site of application. Regardless of application site, translocated BA was ported primarily to expanding leaves, and BA was more readily absorbed by leaf as opposed to stem surfaces. Exogenous application of BA (0, 50, 100 mg ul⁻¹) had no significant effects on tolerance of chili peppers to salt (-0.75 MPa NaCl:CaCl₂, 3:1, w/w) as measured by vegetative and reproductive weights, numbers of reproductive structures, transpiration and total chlorophyll.
18
Rasmussen, Scott Lynn 1958. "The effects of salinity stress on the development of Pythium blight of Agrostis palustris". Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276627.
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Salinity stress predisposed Penncross creeping bentgrass to cottony blight caused by P. aphanidermatum. Studies were conducted on the effects of salinity on the mycelial growth of P. aphanidermatum and on the growth of Penncross bentgrass. Mycelial growth increased significantly up to Ec levels of 7.1 ds/m when compared to mycelial growth at the control Ec levels of 0.5 ds/m. Plant growth was reduced to 50% of the control at Ec levels of 4.3 ds/m. 3-month-old Penncross bentgrass plants were inoculated and incubated at two differing temperatures. At 32 C, all plants died within 3 days regardless of salinity treatment. Rates of plant death were greatest at salinity levels over 2.8 ds/m. At 27 C, plants irrigated with water at Ec levels from 4.3 to 7.1 ds/m showed complete necrosis within 5 days, while treatments irrigated with tap water showed no disease symptoms.
19
Al-Bahrany, Abdulaziz Maatook 1960. "Physiological and biochemical responses of short staple cotton (Gossypium hirsutum L.) to salt stress". Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184634.
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Three cotton (Gossypium hirsutum L.) germplasms (DP62, 84027, and 84033) were used to investigate the physiology of salt tolerance. Lines 84027 and 84033 were developed from the parental line DP62 and showed superior vigor under varying NaCl conditions (0.5 to 2.0 M) during germination and emergence. Proline levels increased in the leaves of all germplasms in response to increasing salinity. Varietal differences in proline levels did not reflect their variation in salt tolerance. Several physiological characteristics were also evaluated under non-saline condition in the greenhouse. There were no significant differences among germplasm sources for all parameters measured. However, salinity reduced transpiration rate, increased leaf diffusive resistance and leaf temperature for all lines. Ribosomal-RNA levels in all germplasms were evaluated after seeds were stressed for 24 hrs in various concentrations of NaCl and then germinated under normal conditions for 72 hrs. Ribosomal-RNA levels were inversely related to salt concentrations. Line 84033 followed by line 84027 had highest ribosomal-RNA content than the parental line DP62 when averaged over the four salt concentrations. Sodium content (ppm/g FW) and Cl⁻ content (ppm/g FW) were evaluated in microsomal and cell walls fractions as well as a cytoplasmic fraction which consisted of vacuoles, mitochondria, and plastids. The Cl⁻ ion exhibited a greater consistency in a concentration shift from one fraction to another as a function of time than did the Na⁺ ion. As a result, there may be a correlation between the drop in ribosomal-RNA and the amount of Cl⁻ in the microsomal fraction. Other parameters measured in the germinating seed were soluble protein (globulin), insoluble proteins (prolamin and glutelin) and fiber percentage. Variations within the germplasms were shown to exist. This study shows that even among lines that have been selected for salt tolerance from a single variety, the possibility exists that each of these lines may have a different mechanism to cope with salt stress.
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Tabot, Pascal Tabi. "The effects of salinity and inundation on salt marsh plants in the context of climate change". Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1019919.
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Ecophysiology studies are needed to predict plant responses in relation to climate change. Variations in salinity and inundation are expected to influence the survival and distribution of salt marsh. The following species were chosen to study as they occur in most South African salt marshes and are representative of different tidal ranges; namely Triglochin buchenaui (lower intertidal), Bassia diffusa (upper intertidal succulent) and Limonium linifolium (upper intertidal non-succulent). To simulate climate change conditions as predicted for South Africa, a 3 x 5 controlled experiment of three inundation levels (tidal, submerged and drought) and five salinity levels (0, 8, 18, 35, 45 ppt) was conducted for each species. This resulted in 15 treatments per species. Plant responses were measured over a three month period. Triglochin buchenaui showed significant variation in height (7.57 ± 0.5 to 29 ± 1.55 cm, p < 0.005, DF = 55) with optimum growth at 0 ppt under tidal conditions; leaf area increments and relative growth rates which decreased with increasing salinity under all inundation states. There was almost a cessation of growth under submergence which reduces the plant’s regeneration potential under these conditions. Proline accumulation (1.84 ± 0.23 to 3.36 ± 0.38 mg l-1), response of photosynthetic pigments and electrolyte leakage (8.17 ± 0.80 to 38.36 ± 7.42 percent) were fundamental to osmotic and membrane response regulation. Plants survived in all inundation states at salinity up to 45 ppt, but the optimum range was 0 to 18 ppt, and best water state was the tidal condition. Viable rhizomes were produced under drought conditions. Bassia diffusa (Thunb.) Kuntze plants under submergence died within one month, irrespective of the salinity. Optimum growth occurred in plants of the tidal treatment at 18 ppt, and reduced with increased salinity and drought conditions. Plants in the tidal treatments were more succulent than the drought-treated plants. There was reduced leaf mass and high anthocyanin concentrations in drought-treated plants and these effects increased with salinity. Soil and leaf water potential were positively correlated with anthocyanin concentration in leaves and stems, suggesting anthocyanin accumulated in response to drought and could be an adaptation to lower the plant’s water potential under drought conditions. A shift of anthocyanin from leaves to stems was found in drought-treated plants, and this possibly enables the maximization of photosynthesis in leaves, to complement its role in osmotic balance and photo-protection. Growth of Limonium linifolium showed that the plant was tolerant to a wide range of salinity under both tidal and drought conditions, but was susceptible to complete submergence, with high membrane damage even in tidal-treated plants. Plants died within 2 weeks of complete submergence. Results further indicated that L. linifolium tolerates extreme drought by accumulating large quantities of proline and oxalic acid, which consequently lowers its water potential for uptake of soil water of high salinity. Excess salts were excreted through salt glands. This is an important adaptation for a plant that thrives in a highly variable saline habitat Further investigation of submergence effects on upper intertidal species using B. diffusa showed three key stages in the response. A drop in chlorophyll a+b within 6 hours (4.2 ± 0.2 to 2.4 ± 0.3 mg l-1) with a corresponding increase in carotenoid concentration (0.6 ± 0.1 mg l-1) indicated an immediate response to submergence. Oxalic acid concentration was highest on Day 4 (13.6 mM) as opposed to control levels, indicative of its role in submergence tolerance, thus Day 4 may be the peak of positive acclimation. The third phase was marked by a sharp increase in electrolyte leakage to 47.5 ± 2.6 percent on Day 10, from 9.4 ± 1.4 percent on Day 7, with a corresponding decrease in total dissolved solutes between Days 7 and 10. Results suggest that oxalic acid accumulates under submergence possibly as a stabilizing osmolyte. The threshold for tolerance of the species under submergence is 7 days with membrane damage thereafter. Bassia diffusa would not survive prolonged submergence (> 7 days) but could survive submergence of short duration (< 7 days) through continuous underwater photosynthesis, accumulation of osmolytes such as oxalic acid and carotenoid, and maintenance of relative water content and succulence within control levels. When considered together, results showed that the two upper intertidal species were sensitive to waterlogging and would not survive complete submergence, whereas the lower intertidal species could in addition to its natural range, thrive in conditions typical of the upper intertidal range, namely prolonged dry conditions and high sediment salinity. These results have important implications for the future management of salt marshes under predicted climate change conditions. In permanently open South African estuaries, a landward migration of salt marsh will be possible if coastal squeeze is limited and the rate of landward recruitment is on par with sea level rise. In this case salt marsh species would retain their current zonation while shifting inland. Increased sea storms and saltwater intrusion could lead to high salinity concentration in the sediment and significantly reduce growth of salt-sensitive plants. In estuaries that are temporarily open to the sea, reduced freshwater inflow will result in an increase in mouth closure, high water levels, prolonged submergence, and consequently die back of salt marsh vegetation. On the other hand increased abstraction and drought would result in low water levels and high sediment salinity which would decrease growth and survival of salt marsh. This research has provided new knowledge on the ecophysiology of salt marsh plants which can be used to predict the responses of plants to climate change.
21
Cepeda, Jose de los Angeles 1955. "Nitrogen fixation by alfalfa as affected by osmotic potentials and measured by nitrogen-15 techniques". Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276591.
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One low salt tolerant alfalfa (Medicago sativa L.) cultivar and two germination salt tolerant alfalfa selections were compared for growth and N fixation at four salinity levels (0, -0.3, -0.6 and -1.2 Mpa). In the first experiment a Hoagland's solution at 5 ppm-N was used; in the second experiment the solution had a 1 ppm-N concentration and supplemental light was used. No significant differences were found among the cultivars. This provides additional support that germination salt tolerance is not necessarily related to salt tolerance for growth. Nitrogen fixed to the first harvest was 61, 48, 49, and 27% of the total shoot N for plants in the control, -0.3, -0.6, and -1.2 Mpa solutions, respectively. At the second harvest, N fixation percentages were 94, 89, 80, and 57% for the corresponding salinity levels which showed significant reduction in N fixation at -0.3 Mpa. The evaluation of N fixation was by 15N techniques.
22
Poteet, David Charles 1953. "Biochemical and physiological adaptations of alfalfa to germination stresses imposed by sodium-chloride". Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277063.
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Nine cycles of recurrent selection for germination salt tolerance in alfalfa (Medicago sativa L.) were compared with their parental cultivar, 'Mesa-Sirsa'. Test seeds were produced in the same season and locale. Cycle 9 and Mesa-Sirsa showed 90% and 2.5% germination, respectively, in a -1.7 MPa NaCl medium. Cycle 8 germinated more vigorously compared to Mesa-Sirsa in stressed and non-stressed environments. Selection also enhanced germination speed and radicle length. Fresh seed and one year old seed showed similar percent germination. Scarification decreased germination in a saline solution. Mesa-Sirsa and Cycle 8 displayed the same pattern of water uptake in a salt solution. Salinity decreased water uptake in Cycle 8 and Mesa-Sirsa compared to the control. Cycle 8 and Mesa-Sirsa contained 7% galactomannan and 3.2% stachyose. Galactomannan was not an important factor in seed salt tolerance. Seed protein content was stable throughout the cycles of selection. Selection for germination salt tolerance in alfalfa significantly affected the percentage of seed amino acids.
23
Badenhorst, Petrus Cornelius. "Identification of molecular markers for Thinopyrum distichum chromosomes contributing to salt tolerance". Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51794.
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Thesis (MSc.)--University of Stellenbosch, 2000.ENGLISH ABSTRACT: The detrimental effect of soil salinity on crop production is a growmg problem worldwide (Tanji, 1990b). The degree to which plants can tolerate high concentrations of salt in their rooting medium is under genetic control with different genetic and physiological mechanisms contributing to salt tolerance at different developmental stages (Epstein & Rains, 1987). Only limited variation exists for salt tolerance in the cultivated cereals. This has prompted attempts to select tolerant progeny following hybridisation of cultivated species and wild, salt-tolerant species. Thinopyrum distichum, an indigenous wheatgrass that is naturally adapted to saline environments (McGuire & Dvorak, 1981), was crossed with triticale (x Triticosecale) in an attempt to transfer its salt tolerance and other hardiness characteristics (Marais & Marais, 1998). The aims of this study were to (i) identify Thinopyrum chromosomes carrying genes for salt tolerance and to identify molecular markers for these chromosomes, (ii) identify a number of diverse monosomic and disomie addition plants. Bulked segregant analysis (BSA), in combination with AFLP, RAPD and DAF marker analysis was implemented to screen for polymorphisms associated with salt tolerance. Five putative AFLP markers and two RAPD markers were detected using bulks composed of salt tolerant plants and bulks composed of salt sensitive plants. The distribution of the markers in these bulks suggests that more than one Thinopyrum chromosome carry genes for salt tolerance. Salt tolerant monosomic and disomie addition plants were characterised for AFLP, RAPD and DAF polymorphisms in an attempt to find markers associated with the chromosome(s) conditioning salt tolerance. One salt tolerant monosomic and one disomie addition plant was identified. One AFLP and two RAPD markers were identified for the Thinopyrum chromosome( s) present in the monosomic addition plant, while three AFLP and three RAPD markers were identified for the disomie addition plant. An attempt was also made to identify diverse chromosome addition plants having complete or near complete triticale genomes plus an additional random Thinopyrum chromosome. Plants with 2n = 43 /44 were identified and characterised for molecular markers (AFLP and RAPD). Cluster analysis was used to group the putative monosomic or disomie addition plants according to the specific Thinopyrum chromosomes they retained. Seventeen AFLP and RAPD markers could be used to group the 24 putative addition plants into six broadly similar groups with different additional Thinopyrum chromosomes. While the members of each group are likely to carry the same additional Thinopyrum chromosomes, this may not necessarily be the case as the interpretation of the marker results is complicated by heterogeneity among plants with regard to the triticale background chromosomes they possess. It is also likely that chromosome translocations occurred during backerossing which may further complicate data. Nonetheless, it is now possible to select disomie addition plants from each group that are likely to represent different Thinopyrum chromosomes. The data will also be useful in future attempts to find further addition plants carrying the remaining Thinopyrum chromosomes.
AFRIKAANSE OPSOMMING: Die skadelike effek van grond versouting op gewasproduksie neem wêreldwyd toe (Tanji, 1990b). Die mate waartoe plante hoë konsentrasies sout in die wortelstelsel kan hanteer is onder genetiese beheer en verskillende genetiese en fisiologiese meganismes dra by tot die soutverdraagsaamheid tydens verskillende ontwikkelingstadia (Epstein & Rains, 1987). Slegs beperkte variasie bestaan vir soutverdraagsaamheid in verboude grane. Dit het aanleiding gegee tot pogings om soutverdraagsame nageslag te selekteer na hibridisasie van verboude spesies en wilde, soutverdraagsame spesies. Thinopyrum distichum, 'n inheemse koringgras, wat aangepas is by brak omgewings (McGuire & Dvorak, 1981), is met korog (x Triticosecale) gekruis in 'n poging om die gene vir soutverdraagsaamheid en ander gehardheidseienskappe oor te dra (Marais & Marais, 1998). Die oogmerke van hierdie studie was om (i) Thinopyrum chromosome te identifiseer wat gene bevat vir soutverdraagsaamheid en molekulêre merkers te vind vir hierdie chromosome, (ii) 'n aantal diverse monosomiese en disomiese addisieplante te identifiseer. Bulksegregaatanalise (BSA), gekombineer met AFLP-, RAPD- en DAF-merkeranalise, is gebruik om polimorfismes geassosieerd met soutverdraagsaamheid op te spoor. Vyf moontlike AFLPmerkers en twee RAPD-merkers is geïdentifiseer met gebruik van bulks bestaande uit soutverdraagsame plante en bulks bestaande uit soutgevoelige plante. Die verspreiding van die merkers in soutverdraagsame bulks dui daarop dat meer as een Thinopyrum chromosoom bydra tot soutverdraagsaamheid. Soutverdraagsame, monosomiese en disomiese addisieplante is gekarakteriseer vir AFLP- en RAPD-polimorfismes in 'n verdere poging om merkers te vind vir chromosome betrokke by soutverdraagsaamheid. Een soutverdraagsame monosomiese en een disomiese addisieplant is geïdentifiseer. Een AFLP- en twee RAPD-merkers is geïdentifiseer vir die Thinopyrum chromosoom(e) teenwoordig in die monosomiese addisieplant, terwyl drie AFLP- en drie RAPDmerkers geïdentifiseer is vir die disomiese addisieplant. 'n Poging is ook gemaak om diverse addisieplante te identifiseer met 'n volledige koroggenoom plus 'n addisionele Thinopyrum chromosoom. Plante met 2n = 43 / 44 is geïdentifiseer en gekarakteriseer met molekulêre merkers (AFLP en RAPD). Tros-analise is gebruik om die vermoedelik monosomiese of disomiese addisieplante te groepeer volgens die spesifieke Thinopyrum chromosome wat hulle behou het. Sewentien AFLP- en RAPD-merkers is gebruik om die 24 vermoedelike addisieplante in 6 groepe met verskillende Thinopyrum chromosome te groepeer. Alhoewel dit voorkom of die verskillende plante in 'n groep dieselfde addisionele Thinopyrum chromosoom het, is dit nie noodwendig die geval nie aangesien die interpretasie van die merkers bemoeilik word deur die heterogeniteit tussen die plante wat betref die agtergrond korogchromosome wat hulle besit. Dit is ook moontlik dat chromosoom herrangskikkings plaasgevind het gedurende die terugkruisings, wat die data verder kan bemoeilik. Nietemin, dit is nou moontlik om disomiese addisies te selekteer uit elke groep wat moontlik verskillende Thinopyrum chromosome bevat. Die data kan ook gebruik word om in die toekoms verdere addisieplante te identifiseer wat die oorblywende Thinopyrum chromosome bevat.
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Weeks, Jon Randall 1949. "The growth and water relations of a coastal halophyte, Salicornia bigelovii". Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/191114.
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The succulent, annual euhalophyte, Salicornia bigelovii was grown in 1, 10, 35, 45 and 60 ppt Instant Ocean. This range represents approximately 1/35 to nearly twice the salinity of seawater. The plants in the 4 highest salinities had common final dry weights and seed yields of about 60 and 11 g, respectively, while the 1 ppt plants had 28 and nearly 5 g, respectively. The water relations data reflected the growth and seed production of the plants. The plants in the 4 higher salinities had water potentials sufficient to generate large import gradients and osmotic potentials which contributed to substantial turgors. The 1 ppt plants had a gradient like the rest, but a very low turgor of 0.11 MPa which was barely 23% of that of the lowest of the other treatments. Higher salinities resulted in slightly greater organic and inorganic osmotica contents. Overall, these results suggest a relatively fixed genetic response to a wide range of salinities, as well as an inability to function well at very low salinities. No plant grown at 0 ppt was ever able to reproduce. Therefore, this plant is an obligate halophyte. Experiments in the plant's native coastal estuary indicated meristem water potentials fluctuate with the tides, although they remain about 1.5 MPa below the corresponding soil water potentials. The plants occupy a discrete elevational range throughout the estuary, spending about 1/3 of their daylight hours submerged, and apparently never see dryness. Phenotype differences in the estuary suggest that, within the habitat, pacing and consequent resource domination may be important parameters affecting plant size and possibly fitness. Nitrogen, which is characteristically rare in this and other estuaries, may be critical in this regard. The plants produce large quantities of glycine-betaine, which may be for simultaneous osmoticum use and nitrogen storage. Most roots occur in the first 3 inches of soil. A mechanism is proposed, based on highly efficient compartmentation at the cellular level and the shuttling of organic osmoticum across the tonoplast, by which the tidally based cyclical water potentials could be explained.
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Danon, Avihai. "Molecular events associated with halophytic growth in Lycopersicon pennellii". Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184642.
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We have studied the effects of exogenous salt on whole plant and suspension culture cells of the halophytic tomato Lycopersicon pennellii. Under low salt conditions (2.9 dS/M) plants showed enhanced (halophytic) growth (107% of control). At moderate (7.5 dS/M) and high (18.5 dS/M) salt levels, salt stress reduced growth to about 78% and 40% of control respectively. Salt-induced changes in root mRNAs were analyzed via two-dimensional PAGE of cell free translation (CFT) products. We have identified 14 proteins whose levels were enhanced by exogenous salt. One of these proteins was unique to low salt induced halophytic growth. This system allowed for discrimination between proteins up-regulated at all salt levels and those up-regulated only during salt stress induced growth reduction. Ten proteins were identified whose levels were reduced by exogenous salt. Once again, one could identify a subset of proteins whose levels were reduced only under salt stressed conditions. Proteins identified in this study are candidates for roles in growth maintaining stress adaptive metabolism in L.pennellii. These data underscore the complexity of the genetic control of salt metabolism in higher plants. The effects of exogenous salt on protein synthesis and accumulation were studied in suspension cultures of L.pennellii. Two salt levels were applied to the cells. Under low salt conditions (LS, 10 mM), L.pennellii cells showed enhanced (halophytic) growth. Under high salt conditions (HS, 50 mM), the cells showed reduced (salt-stressed) growth. Changes in proteins with time were analyzed by a combination of cell free translation, in vivo labeling and total accumulated protein. In vivo labeling studies showed that the pattern of steady state protein synthesis was disrupted shortly after addition of salt. High salt induced greater disruption in the pattern. Over time, the steady state levels of most proteins shifted back towards those of the unstressed-control. However, the level of several proteins remained altered. Analysis of proteins whose levels increased with exogenous salt showed differences in the response patterns that may allow for discrimination between proteins involved in growth maintaining and stress shock responses.
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Attumi, Al-Arbe. "Effects of salt stress on phosphorus and sodium absorptions by soybean plants". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0001/MQ44119.pdf.
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Griffiths, Megan Elizabeth. "Salt spray effects on rare New England coastal sandplain heathland plant communities /". Thesis, Connect to Dissertations & Theses @ Tufts University, 2003.
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Thesis (Ph.D.)--Tufts University, 2003.Adviser: Colin M. Orians. Submitted to the Dept. of Biology. Includes bibliographical references (leaves 181-200). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Lawson, Inez Ilicia. "Invertebrate Community Composition Across Inundation Regimes and Its Potential to Reduce Plant Stress". PDXScholar, 2017. https://pdxscholar.library.pdx.edu/open_access_etds/3891.
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Appreciation of the ecological and economic values associated with healthy salt marshes has led to a recent rise in the number of marshes that are being targeted for restoration by dike removal. The success of restoration is often measured by the return of marsh plants, though this overlooks a key component of salt marshes, that of the invertebrate community within marsh sediments. To evaluate the short-term recovery of these invertebrates, sediment cores were collected across an elevational gradient in a recent dike removal marsh, one and two years post removal, and a nearby reference marsh. Abundance, richness and diversity as well as morphospecies community composition were compared across treatment groups (Reference, Removal) and elevation zone (High Marsh, Low Marsh). Morphospecies richness, abundance and diversity were significantly higher in Low Marsh samples than in High Marsh samples, though no statistically significant differences were found across treatments of the same elevation (e.g., Reference Low Marsh versus Removal Low Marsh). Pair-wise ANOSIM results found significant differences between community compositions across treatments, specifically Reference Low Marsh and Removal Low Marsh.
The marsh edge, the lowest point of vascular plant growth before transitioning to tide flats, is considered a high stress environment for emergent vegetation. Plant establishment and survival in this low elevation zone is limited by the tolerance to inundation duration and frequency and anoxic sediments. Bioturbation and burrowing by macroinvertebrates increases the surface area exposed to surface water for gas exchange, increasing the depth of the redox potential discontinuity layer. Crabs that make stable, maintained burrows have been shown to increase oxygen penetration into sediment, improving plant productivity. Such crabs are not found in salt marshes of the Pacific Northwest of North America. However, other burrowing invertebrates may have a positive impact on plant health in these areas by reducing abiotic stress due to anoxic sediments, thereby allowing plants to establish and survive lower in the intertidal zone. To assess this potential relationship, study plots of Distichlis spicata were selected at equivalent elevations at the lowest point of plant establishment at the marsh edge. Focal plant rhizomes were severed from upland ramets and assigned an invertebrate abundance treatment based on a visual burrow count surrounding each plant (9 cm diameter). Focal plants were visited monthly from July to September 2016, plant health variables of chlorophyll content and chlorophyll fluorescence (photosynthetic efficiency), and sediment ORP readings were collected. Plant survivorship was significantly higher in plots with invertebrates, 96% of plants in 'With Invertebrate' plots and 50% of plants in 'No Invertebrates' plots survived the duration of the study. Plant health (chlorophyll content and chlorophyll fluorescence) generally increased with increased invertebrate presence though, not statistically significant. There may be potential for improved plant productivity and resilience to plants at the marsh edge due to invertebrate burrowing activity. This benefit could help mitigate projected losses in plant productivity due to sea level rise, though more research is needed to investigate the mechanism by which these invertebrates confer a health benefit to plants at the marsh edge.
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Sessoms, Holly Nicol. "Water use potential and salt tolerance of riparian species in saline-sodic environments". Thesis, Montana State University, 2004. http://etd.lib.montana.edu/etd/2004/sessoms/SessomsH0805.pdf.
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Morita, Tateo 1958. "Effect of inbreeding on germination salt tolerance in alfalfa". Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276644.
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The performance of an alfalfa (Medicago sativa L.) population has been improved by recurrent selection for germination salt tolerance. However, recurrent selection may lead to increased inbreeding. Since alfalfa is subject to severe inbreeding depression, accumulation of inbreeding during the selection process may negatively affect performance. This experiment was designed to determine the effects of inbreeding on germination performance in alfalfa under saline and non-saline conditions. The germination performance of seed having three different levels of inbreeding as examined. No adverse effects of inbreeding were observed in non-saline conditions. Consistent (but nonsignificant) declining trends were observed in germination percentage in saline conditions as the level of inbreeding increased. Proportionately larger declines were observed between generations in germination speed and early seedling vigor. These results suggest heterozygosity in alfalfa may be maintained simultaneously while recurrent selection for germination salt tolerance is conducted. Moreover, reducing inbreeding during recurrent selection for germination salt tolerance may be more successful if germination speed index or early seeding vigor are used for the measurement.
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Alemayehu, Makonnen. "Germination and emergence salt tolerance of sorghum (Sorghum bicolor L.) as influenced by seed quality and generations". Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184933.
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Artificially aged and non-aged seeds of 22 grain sorghum (Sorghum bicolor L.) F₁ hybrids and their F₂ and F₃ generations were evaluated for germination salt tolerance. Six of the hybrids, along with their F₂ and F₃ generations, were tested for emergence salt tolerance. Effects of seed production environments on germination salt tolerance were also studied using F₂ generations of 12 sorghum hybrids produced under full-season irrigation, limited irrigation, and double-cropping conditions. Germination tests were conducted in a growth chamber, on trays, while the emergence test was conducted in a greenhouse in flats filled with sand. The experiments were conducted under non-saline and saline conditions in randomized complete block designs. Artificial seed aging resulted in significant reductions in germination percentages under both non-saline and saline environments. The overall mean reduction in germination caused by seed aging was more than twice as much under salinity stress as under the non-stress conditions (48 vs. 17%), indicating differential effects of salinity on different quality seeds. Entries that appeared to be resistant to seed aging also had higher germination percentages under salinity stress. Seed production environment influenced germination performance in both non-saline and saline environments. The overall mean germination percentages of sorghum seeds produced under three different field environments were significantly different from one another. Significant differences were observed in germination and emergence percentages within F₁, F₂, and F₃ generations. Except for the F₁ entries, however, emergence index differences within the F₂ and F₃ generations were not significant. Correlations between germination and emergence percentages in the non-saline and saline treatments were generally nonsignificant. This suggests that germination and emergence responses of sorghum may vary under different salinity levels and different environments.
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Goertz, Steven Harvey. "Salt tolerance of tepary (Phaseolus acutifolius Gray) and navy (P. vulgaris L.) beans at several developmental stages". Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184646.
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Two accessions of tepary (phaseolus acutifolius Gray var. latifolius) and navy (P. vulgaris L. 'Fleetwood') beans were studied for salt tolerance at several• developmental stages. Genotypes were germinated at 0.0 through -2.5 MPa NaCl at 25°C and 35°C for nine days. Tepary accessions had higher germination percentages and rates than navy for ≤ - 2.0 MPa at 250C and ≤ - 1.5 MPa at 35°C. Fresh weights of root plus hypocotyl decreased severely with the first increment of NaCl (-0.5 MPa) for all genotypes. Fresh weight of navy was reduced more at 35°C than at 25°C. Genotypes were stressed in vermiculite-filled trays with 0.0 through -1.5 MPa NaCl for 14 days. Final growth stage and rates of emergence were reduced at salinities ~ -0.6 MPa NaCl, and were higher in tepary than navy at -1.2 MPa. Tepary beans tended to maintain higher water and osmotic potentials, and at -0.9 MPa had less reduction in leaf area than navy beans. Fresh weights, dry weights and root:shoot ratios declined in all genotypes with increasing salinities. Plants grown hydroponically were stressed with -0.10, -0.25, and -0.50 MPa NaCl during either vegetative or reproductive stages. Navy had equal or greater fresh and dry weights of leaf, stem, and pods at -0.10 MPa, but tepary beans had equal or greater weights at the highest salinity relative to navy. Tepary had the greatest pod weight with -0.50 MPa NaCl applied during the reproductive stage. Carbon exchange rates (CER) were lower in navy than one or both tepary beans at some sampling times. Tepary beans tended to have higher leaf water and osmotic potentials than did navy. Transpiration and stomatal resistance values were similar in all genotypes, while leaf temperatures were different in white tepary versus navy. Tepary beans yielded higher than navy when grown in low and high salinity fields. Transpiration rates, leaf water and osmotic potentials, and CERs were similar or higher, while stomatal resistance and leaf temperatures were similar or lower in tepary than in navy. Plant height and stand count also were measured. Tepary was more salt tolerant than navy, exhibiting greater tolerance to NaCl at every growth stage.
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Alislail, Nabeel Yonnis. "Influence of sodium chloride on tepary (Phaseolus acutifolius Gray) and navy (Phaseolus vulgaris L) beans". Diss., The University of Arizona, 1990. http://hdl.handle.net/10150/184985.
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Shoot and root fresh and dry weight, shoot length, leaf area, leaf area index and relative growth rate of 14 day old tepary bean (Phaseolus acutifolis Gray) and navy bean (Phaseolus vulgaris L.) seedlings were reduced following treatment with NaCl solution exhibiting osmotic potential of either -0.25, 0.50, and -0.75 MPa. Salinity reduced the growth of navy bean more than tepary bean. The physiological basis of the adaptive response of tepary bean seedlings to salt stress was explored by determining the water and osmotic potentials, relative water content, free amino acid and sugar concentrations, distribution and levels of inorganic ions within the seedlings and ATPase activity of the root plasma membrane. Salinity led to an osmotic adjustment in the leaves and the proximal part of the root of tepary bean. Turgor remained almost constant whereas osmotic and water potential and relative water content declined following the salt treatments. The osmotic adjustment of the leaves and proximal part of the roots was -1.7 MPa and -1.2 MPa, respectively, in seedlings treated with -0.75 MPa NaCl solution. Free amino acids and sugars increased under salinity stress in both species but they increased more in the tepary bean. Glucose was the most abundant free sugar. The nonstructural carbon solutes contributed -0.15 MPa to the seedling's osmotic adjustment whereas Na, Cl, K and Ca ion levels contributed -0.85 MPa. However, the levels of these solutes were not large enough to account for the total osmotic adjustment observed in the salt treated seedlings. This study shows that tepary bean has specific strategies to overcome the impact of salinity through osmotic adjustment and exclusion of Na and Cl ions from the stems and leaves by retaining these ions in the proximal part of root and stem base. (Abstract shortened with permission of author.)
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Hyder, Jennifer A. "An Investigation of the Effects of Increased Tidal Inundation, Competition, and Facilitation on Salt Marsh Systems". Thesis, University of South Florida, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3700275.
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The low-lying topographic nature of salt marshes makes plants in these communities particularly vulnerable to increased salinity and inundation exposure associated with sea level rise. Both increased salinity and inundation have been cited as major causes of reduced plant performance and survival in marsh and areas fringing marsh. In addition to limitations imposed by physical stress, interspecific interactions have also been shown to mediate the performance and survival of salt marsh and salt marsh fringing species. The Stress Gradient Hypothesis (SGH) postulates that species interactions shift from competitive to facilitative as stress levels increase and predicts that (a) the frequency and intensity of facilitative interactions increase as conditions become more stressful for plants and (b) the strength of competitive interactions increases as abiotic stress levels diminish. The SGH has been rigorously tested to examine how both the frequency and intensity of species interactions change under varying physical stress levels. Studies conducted in salt marsh systems have shown facilitation to be as strong of a driving force as competition in influencing plant performance and survival and have shown that while competition appears to be the pervasive force in the less physically stressful terrestrial zones fringing salt marshes, facilitation influences the performance and survival of species in harsher marsh areas. Under conditions of sea level rise, it remains unclear if the nature of interspecific interactions would shift as stress levels change. This research endeavors to examine the interplay between abiotic stresses and biotic interactions under conditions of increased salinity and inundation exposure.
The first study presented here investigated the effects of increased inundation and soil salinity associated with sea level rise on four salt marsh fringing species, and assesses how competition and facilitation impact survival of salt marsh fringing plant survival under these changing conditions. All plant species experienced reduced growth and photosynthetic inhibition below their current distributional positions, both in the presence and absence of neighboring above ground vegetation. The findings also signal a potential shift in the nature of interspecific interactions from competition to facilitation to neutral as plants begin to experience increased salt and inundation exposure.
The second study aimed to disentangle the effects of increased soil salinity and increased soil moisture on four salt marsh fringing species, and to examine the effects of plant neighbors. The results showed that fringe plants exposed to increased inundation experienced a two-fold reduction in performance and survival over 750 g pure salt addition, suggesting that inundation may be a more important limiting factor than salinity with rising sea levels. Landward transplants at the forest-fringe margin exposed to lower soil salinity and decreased inundation exhibited a three-fold increase in performance and survival when compared to controls. Neighbor manipulation studies, which consisted of trimming neighboring vegetation to ground level, again suggested that interspecific interactions in salt marsh fringing species may shift from competitive to facilitative with climate-induced sea level rise. Overall, our findings suggest that salt marsh fringing species may not be able to tolerate changing conditions associated with sea level rise and their survival may hinge on their ability to migrate towards higher elevations.
The final experiment tested the Stress Gradient Hypothesis and investigated the relative importance of facilitation and competition in a salt marsh system under varying stress levels. This study also ascertained whether salt or inundation exposure is the primary influence on salt marsh plant performance and survival. As in previous studies, our findings suggest that many salt marsh plants don't require, but merely tolerate harsher abiotic conditions. The results showed that plants at higher elevations were depressed by strong competitive pressure from neighboring fringe species while plants at lower elevations benefited from the presence of neighbors. Collectively, the results of these studies indicate that species interactions are an integral driver of plant distribution in salt marsh communities. Furthermore, our findings indicate that changing stress levels may not always result in a shift in the nature of interspecific interactions. These studies have endeavored to show that the interplay between competition and facilitation interacts with physical processes to determine the growth and performance of both fringe and marsh plant species. The paucity of studies examining the roles of species interactions and changing abiotic stress levels on multiple salt marsh and salt marsh fringing species warrants the need for additional research. The responses of salt marsh and salt marsh fringing species to sea level rise can not only serve as very valuable and sensitive indictors of climate change, but will also aid in predicting the future location of the marsh-fringe-forest ecotone, which is predicted to shift inland as sea levels continue to rise.
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El, Mghadmi Z. Y. "Effect of environmental stresses and growing medium amendment with 'Zander' on growth of Acacia saligna under saline conditions". Thesis, Coventry University, 2011. http://curve.coventry.ac.uk/open/items/5727ee90-f827-485e-93d9-94a9b5456f43/1.
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In Libya salinization of land and ground water is a key problem. A. saligna is one species that offers potential for growth under these conditions. Experiments were undertaken to accelerate the germination of Acacia seeds, and various pre-treatment methods were assayed. Boiling water treatment, mechanical scarification and acid improved germination and germination rate. Sowing A. saligna seeds at 30 mm depth gave greatest seedling growth from large and medium seeds whereas 20 mm was more suitable for small seeds. This study aimed to improve the establishment of Acacia saligna irrigated with saline water, plants were grown for seven weeks under greenhouse or field conditions in (Libya) either sand or soil salinized with varying applications of NaCl. Irrigation with NaCl significantly decreased plant survival and growth and concentration of Ca, Na, K, Fe and P ions in plants with 0.5 M or 1.0 M NaCl. The experiments were repeated using a naturally occurring soil amendment called ‘Zander’. Seeds of A. saligna were grown for seven weeks in both greenhouse and field trials as before but with the addition of Zander and NaCl. Zander improved plant survival and growth with salinity and increased the elements in plants (Ca, Na, K, Fe and P). Field experiments were conducted to assess the effects of saline irrigation with 1.0 M NaCl and extra water added to 0% or 10% Zander on survival and growth, consequently, seedling growth significantly decreased with increase in soil salinity. Survival and growth increased with increase in extra water. The additional irrigation water caused an increase in the uptake of Ca++ and increased the Ca++/Na+ and K+/Na+ ratio. Zander did not appear to reduce net uptake of Na+ and its transport to shoot tissues. Mg++, P, K+ and Ca++ content significantly decreased in plants in response to salinity. Possible mechanisms to avoid Na+ toxicity in A. saligna in response to salinity included increasing the supply of Ca++. Extra Ca++ applied into the medium with and without salt increased survival and growth even in the absence of Zander. Calcium increased uptake of Ca++ and increased Ca++/Na+ and K+/Na+ ratio.
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Woodward, Andrew J. "The use of proline to determine salt tolerance in eucalyptus species and clones". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2004. https://ro.ecu.edu.au/theses/841.
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There have been a number of studies that have examined the Eucalyptus spp. for their salt and waterlogging tolerance: but they have done so using conventional methods. A wide range of plants are known to produce greater amounts of proline when stressed, be it salt, temperature, 'drought or several other types of stress. This study looked at production of proline in salt stressed eucalypts to determine whether it can be used to differentiate between individuals andspecies. A range of Eucalyptus species and salt tolerant clones of E. camaldulensis were grown to investigate their proline response to salt stress.
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Miranda, Casey R. "Effects of Recycled Water On Landscape Plants". DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/354.
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ABSTRACT EFFECTS OF RECYCLED WATER ON LANDSCAPE PLANTS Casey Ray Miranda Recycled water is water that has been previously used, has suffered a loss of quality, and has been properly treated for redistribution (Wu et al. 2001). The use of recycled water as an alternative to fresh water in the landscape can have positive and negative effects. Experimentation on 40 different plant species during a 32 week period (2 phases of 16 weeks), was conducted to analyze the effects of recycled water irrigation on the appearance of landscape plants. Each species of plant was planted into 10 individual number 2 pots and irrigated with recycled water daily. Media and water were tested for nutrients and other constituents. In phase I there were four different species of grasses and grass-like plants, five different perennials, five species of shrubs, and four annuals tested; while phase II tested four species of herbaceous perennials, eight different species of shrubs, six species of groundcovers, and four species of annuals. All tests were conducted at the Paso Robles Waste Water Treatment Plant. Of the grasses and grass like species Yucca spp. and Buchloe spp. performed best. Osteospermum fruticosum, Lavandula angustifolia, Rosmarinus officinalis, Phormium tenax, and Pennisetum setaceum had the best appearance of the herbaceous perennials tested. For the shrubs, Coprosma repens, Cistus purpureus, Dodonea viscosa, Eleagnus pungens, Baccharis pilularis, Ceanothus thysiflorus, Thuja orientalis, and Nerium oleander had the best appearance when irrigated with recycled water. The best annuals were Senecio cineraria, Antirrhinum majus, Primula spp., Viola spp., and Calendula officinalis. Of the groundcovers Heuchera spp., Lonicera japonica, Vinca major, Hedera helix, and Ceanothus griseus had the best results. From the experiment a list of tolerant and non-tolerant plants was compiled (Appendices 1 and 2). While many plants were capable of developing and growing normally, other plants were sensitive to recycled water irrigation. In order to prevent salt damage to plants and expand the use of recycled water, salt tolerance of landscape plant material must be identified (Niu et.al, 2006).
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Whittington, John. "Physiological effects of salinity on chara corallina /". Title page, contents and summary only, 1990. http://web4.library.adelaide.edu.au/theses/09PH/09phw6258.pdf.
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Lintnaar, Melissa. "The physiological responses of salinity stressed tomato plants to mycorrhizal infection and variation in rhizosphere carbon dioxide concentration". Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/52002.
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Thesis (MSc)--Stellenbosch University, 2000.ENGLISH ABSTRACT: This investigation was undertaken to determine whether elevated concentrations of dissolved inorganic carbon (DIC) supplied to plant roots could improve plant growth and alleviate the effects of salinity stress on tomato plants infected with arbuscular mycorrhizae. Lycopersicon esculentum cv. FI44 seedlings were grown in hydroponic culture (pH 5.8) with 0 and 75 mM NaCI and with or without infection with the fungus Glomus mosseae. The root solution was aerated with ambient CO2 (360 ppm) or elevated CO2 ( 5 000 ppm) concentrations. The arbuscular and hypha I components of mycorrhizal infection as well as the percentages total infection were decreased or increased according to the variation in seasons. The plant dry weight of mycorrhizal plants was increased by 30% compared to non-mycorrhizal plants at elevated concentrations of CO2, while the dry weight was decreased by 68% at ambient CO2 concentrations. Elevated CO2 also stimulated the growth of the mycorrhizal fungus. Elevated CO2 increased the plant dry weight and stimulated fungal growth of mycorrhizal plants possibly by the provision of carbon due to the incorporation of HCO)- by PEPc. Plant roots supplied with elevated concentrations of CO2 had a decreased CO2 release rate compared to roots at ambient CO2. This decrease in CO2 release rate at elevated CO2 was due to the increased incorporation of HC03- by PEPc activity. Under conditions of salinity stress plants had a higher ratio of N03-: reduced N in the xylem sap compared to plants supplied with 0 mM NaCI. Under salinity stress conditions, more N03- was transported in the xylem stream possibly because of the production of more organic acids instead of amino acids due to low P conditions under which the plants were grown. The N03· uptake rate of plants increased at elevated concentrations of CO2 in the absence of salinity because the HCO)- could be used for the production of amino acids. In the presence of salinity, carbon was possibly used for the production of organic acids that diverted carbon away from the synthesis of amino acids. It was concluded that mycorrhizas were beneficial for plant growth under conditions of salinity stress provided that there was an additional source of carbon. Arbuscular mycorrhizal infection did not improve the nutrient uptake of hydroponically grown plants.
AFRIKAANSE OPSOMMING: In hierdie studie was die effek van verhoogde konsentrasies opgeloste anorganiese koolstof wat aan plant wortels verskaf is, getoets om te bepaal of dit die groei van plante kan verbeter asook of sout stres verlig kon word in tamatie plante wat met arbuskulêre mikorrhizas geïnfekteer was. Lycorpersicon esculentum cv. FJ44 saailinge was in water kultuur gegroei (pH 5.8) met 0 en 75 mM NaCI asook met of sonder infeksie met die fungus Glomus mosseae. Die plant wortels was bespuit met normale CO2 (360 dele per miljoen (dpm)) sowel as verhoogde CO2 (5 000 dpm) konsentrasies. Die arbuskulere en hife komponente, sowel as die persentasie infeksie was vermeerder of verminder na gelang van die verandering in seisoen. Die plant droë massa van mikorrhiza geïnfekteerde plante by verhoogde CO2 konsentrasies was verhoog met 30% in vergelyking met plante wat nie geïnfekteer was nie, terwyl die droë massa met 68% afgeneem het by gewone CO2 konsentrasies. Verhoogde CO2 konsentrasies het moontlik die plant droë massa en die groei van die fungus verbeter deur koolstof te verskaf as gevolg van die vaslegging van HCO)- deur die werking van PEP karboksilase. Plant wortels wat met verhoogde CO2 konsentrasies bespuit was, het 'n verlaagde CO2 vrystelling getoon in vergelyking met die wortels by normale CO2 vlakke. Die vermindering in CO2 vrystelling van wortels by verhoogde CO2 was die gevolg van die vaslegging van HC03- deur PEPk aktiwiteit. Onder toestande van sout stres, het plante 'n groter hoeveelheid N03- gereduseerde N in die xileemsap bevat in vergelyking met plante wat onder geen sout stres was nie, asook meer NO)- was in die xileemsap vervoer moontlik omdat meer organiese sure geproduseer was ten koste van amino sure. Dit was die moontlike gevolg omdat die plante onder lae P toestande gegroei het. Die tempo van NO.; opname was verhoog onder verhoogde CO2 konsentrasies en in die afwesigheid van sout stres omdat die HCO)- vir die produksie van amino sure gebruik was. In die teenwoordigheid van sout was koolstof moontlik gebruik om organiese sure te vervaardig wat koolstof weggeneem het van die vervaardiging van amino sure. Daar is tot die slotsom gekom dat mikorrhizas voordelig is vir die groei van plante onder toestande van sout stres mits daar 'n addisionele bron van koolstof teenwoordig is. Arbuskulere mikorrhiza infeksie het 'n geringe invloed gehad op die opname van voedingstowwe van plante wat in waterkultuur gegroei was.
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Drake, Arly Marie. "EFFECT OF PLANT GROWTH REGULATORS ON CREEPING BENTGRASS GROWTH AND HEALTH DURING HEAT, SALT, AND COMBINED HEAT AND SALT STRESS". The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1546450732510932.
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Hendrati, Rina Laksmi. "Developing systems to identify and deploy saline and waterlogging tolerant lines of Eucalyptus occidentalis Endl". University of Western Australia. Faculty of Natural and Agricultural Sciences, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0036.
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[Truncated abstract] Eucalyptus occidentalis, a timber species from south Western Australia, is highly salt and waterlogging tolerant. Screening identified genotypes tolerant of high salt concentrations and waterlogging. Tolerance at provenance, family and individual level, and how phenotypic performance under salt and waterlogging was inherited was explored to provide a breeding population. Salt and/or waterlogged screening was carried out under controlled conditions up to extreme salt levels to determine tolerance between genotypes. This tank method was shown to produce repeatable results. Seedlings of 30 families from 9 provenances were used for screening. At low salt concentration (up to 300 mM NaCl), differentiation occurred for some traits but in general there was only a slight reduction in growth under salt, and waterlogging alone was not detrimental. At high salt concentration (550 mM) differentiation occurred among genotypes for all traits. Equivalent genotypes were also planted in field trials at three sites, two with medium (583 - 847 mm) and one with low rainfall (372 - 469 mm), in southern Western Australia. Survival was low (<53%) after 9 months due to an exceptional dry season followed by 3 months waterlogging in Kirkwood (38 - 1360 mSm-1), but was high >89% after 33 months in saline fields in Sandalwindy (96 - 976 mSm-1) and Roberts (88 - 1424 mSm-1). Some families were similarly in high rank for height under saline conditions in controlled and field trials. Height had the highest narrow-sense heritability value, especially under controlled saltwaterlogging (0.85) treatment and 20% selection enabled a gain of 8-14% under controlled conditions and in the field. Leaf production under salt was not an inherited trait. Systems were developed to hasten deployment of selected material. Extended daylength (16 h) and paclobutrazol (1 mg a.i/mm stem circumference) stimulated flowering in 2 year-old plants. Clonal propagation was possible. Grafting success varied from 0-100% depending on scion/rootstock provenances. ... There was only a slight reduction in heterozygosity from species level to provenance and family levels, and two superior genotypes maintained high diversity. v Crossing was possible using one stop pollination of cut immature styles and capsule retention varied from 0-34% and germination rate from 2-96%. Genetic distance between parents was correlated with seed set and offspring fitness. Wider genetic distances increased capsule retention, seed germination and seedling survival. Under 500 mM salt-waterlogging, offspring heights were similar when parental genetic distances were similar. High heritability value for height from ANOVA-REML parental screening was confirmed using parent-offspring regression. Screened superior genotypes, which withstood very high salt concentration, provide a breeding population for further breeding and for plantations under saline regions in low-medium rainfall areas in Western Australia and other parts of the world. These trees provide an economic return in areas where no other plants may survive and an environmental service in potentially reducing waterlogging, salinity and its spread.
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Gadeh, H. M. "The effect of compost and priming on the salt tolerance of bread wheat (Triticum aestivum L. cv. S-24 and cv. Slambo) during germination and early seedling establishment". Thesis, Coventry University, 2013. http://curve.coventry.ac.uk/open/items/f0bd31e5-d16c-4435-993a-ab1ec64d7bc3/1.
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Soil salinity and the arid climate in Libya are major constraints in agriculture and predominantly in foodstuff production which are limiting wheat production and yield. The effect of pre-sowing seed treatments with 50 mM of KCl, NaCl, CaCl2, and distilled water as hydropriming on germination and early seedling growth in two wheat (Triticum aestivum L.) cultivars S-24 (tolerant) and Slambo (untested before) under 0, 100, 200 and 300 mM NaCl concentrations was examined. CaCl2 was the only priming treatment that significantly improved the germination percentage, germination rate, and mean germination time in both cultivars under almost all NaCl concentrations. Thus, priming with CaCl2 was selected for further experiments. In the greenhouse, seeds primed with 50 mM of CaCl2 also improved the emergence percentage, emergence rate, shoot and root length, and fresh and dry weight of shoots and roots of both cultivars under all NaCl concentration except at 300 mM where the emergence was completely inhibited. The response of wheat cultivars to three compost treatments including cow manure compost (CC), greenwaste compost (GC) and 50:50 mixture (mix) between them and sand at percentage inclusions of 10 and 30 % by weight under 0, 100, 200, and 300 mM of NaCl was also investigated. Among all compost treatments, 30% GC and 30% mix were the best treatment and improved almost all growth parameters under salt stress, and 30% GC was also the only treatment that had any emergence at 300 mM NaCl. 30% GC and 30% mix were selected for further experiments. The effect of the combination of the selected priming agent (CaCl2) and the best two compost treatments (30% GC and 30% mix) on the emergence and early seedling growth of both cultivars was tested. The results showed that all the treatments enhanced plant growth parameters including seedling ion uptake in both cultivars, with preference to primed seeds sown in 30% GC. The treatments had the following order of the performance of both cultivars under salt stress. Primed seeds sown in 30% GC > unprimed seeds sown in 30% GC > primed seeds sown in 30% mix > unprimed seeds sown in 30% mix. This enhancement is possibly due to the provision of Ca2+ and / or the improvement in the availability of water as both of them were improved by the application of priming and compost.
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Saif, Salman Mohammed 1958. "EFFECT OF SALINITY ON THE TOMATO PLANTS GROWN IN A HYDROPONIC SYSTEM". Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/277070.
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Keyster, Marshall. "Nitric oxide-mediated signaling in legumes and its role in maize responses to salt stress". Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6565.
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Rawahy, Salim Ali 1951. "EFFECT OF SODIUM-CHLORIDE, SODIUM-SULFATE AND CALCIUM-CHLORIDE SALTS ON NITROGEN AND PHOSPHORUS UPTAKE BY TOMATO PLANTS (SALINITY, OSMOTIC PRESSURE, SPECIFIC ION EFFECT)". Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/275527.
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Mohamed, Gadija. "The effects of gallic acid on the membrane proteome and antioxidant system of wheat plants under salt stress". University of Western Cape, 2020. http://hdl.handle.net/11394/8252.
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>Magister Scientiae - MScSalt stress is a major abiotic stress that accounts for huge agricultural losses worldwide, which in turn threaten food security and sustainable agriculture. Salt triggers the excessive production of reactive oxygen species (ROS) which accumulate to levels that become toxic to plants, resulting in cell death and reduced plant growth. Part of the plant’s mechanisms to counteract ROS-induced cell death involves the scavenging ability of the antioxidant defense system to maintain redox homeostasis. Gallic acid (GA) is an antioxidant that has been shown to reduce salt-induced ROS in legume plants. However, its effects on wheat plants have not been elucidated. This study thus investigated the role of exogenous GA (250 μM) on the physiological responses and antioxidant system of wheat plants under salt stress (150 mM). In addition, this study also investigated how GA and salt stress influenced changes in the membrane proteome of wheat plants using LC-MS proteomic analysis.
2022
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Helmy, Magdi Mourad Mohammed. "Salinity-fertility interaction with macro and micronutrients in maize (Zea mays) plants". Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184298.
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In two greenhouse experiments, the response of maize plants (Zea mays L.) to macro and micronutrient fertilizers was studied. The first experiment was conducted in Cairo, Egypt in which maize plants were grown on saline soils with ECₑ values of 1.42, 6.12 and 12.1 dSm⁻¹ and fertilized with N, P, K alone and in combination. It was found that maize plants produced the highest dry matter when NP fertilizers were added in the Ca-form compared to the other fertilizer treatments, and this positive response decreased with increasing salinity level. Also, it was found that application of P and K fertilizers either alone or together as PK augmented the adverse effect of salinity on dry matter and nutrients uptake. In addition, the concentration and uptake of Na⁺ ions in the shoot tissues decreased with increasing salinity level up to ECₑ 12 dSm⁻¹. This could be due to Na+ exclusion or accumulation in root tissues. However, application of N and P fertilizers tended to decrease plant content of micronutrients, particularly Fe as well as Zn at high salt levels. The second experiment was conducted in a University of Arizona campus greenhouse. A Pima soil from the Marana area was artificially salinized with NaCl, Na₂SO₄, CaCl₂, and Mg₂SO₄ salts almost to the salinity levels mentioned above. Maize plants were grown and fertilized with NP fertilizer as a basic dressing. Chelated forms of Zn, Fe, and Mn were added with two different methods; soil and foliar spray application. Two pH values of spray nutrient solutions were used; pH 6 and pH 8. Data obtained showed increased dry matter and nutrient uptake in response to spraying maize plants with Zn + Fe or Zn+ Fe + Mn at pH value of 8 at the medium salt level relative to the other treatments. However, maize plants also showed high dry matter and nutrient uptake in response to Zn + Fe + Mn soil application at the high salt level, although Zn-pH 8 gave unexpectedly high dry matter production. It seems probable that this high dry matter obtained could be due to the effect of high pH spray treatment on increasing the activity of some enzymes, e.g. PEP-carboxylase and/or ribulose 1,5 diphosphate carboxylase, as well as the increase in rate of translocating the photosynthates and this effect was augmented by the nutrient(s) applied. Also, it was found that Na uptake decreased while total chlorophyll and chlorophyll a content increased with increasing salinity level. The increase in the chlorophyll content could be due to either Na exclusion by the plants and/or the decrease plant growth due high salts.
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Al-Bahrany, Abdulaziz Maatook 1960. "PHYSIOLOGICAL RESPONSES OF TOMATO CULTIVARS SUBJECTED TO SALINITY (GERMINATION, RESPIRATION)". Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/276460.
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Rohal, Christine B. "Invasive Phragmites australis Management in Great Salt Lake Wetlands: Context Dependency and Scale Effects on Vegetation and Seed Banks". DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7228.
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Invasive plants can outcompete native plants, replacing diverse plant communities with monocultures, which can negatively impact the whole ecosystem. One invasive plant, Phragmites australis, has invaded wetlands across North America. In Utah’s Great Salt Lake, it has greatly reduced the area of native plants that are important habitat for migratory birds. Here we describe experiments that assess multiple treatments for Phragmites removal and evaluate the return of native plants after Phragmites management. The treatments were applied to Phragmites patches at two scales (small 1/4-acre plots and large 3-acre plots) and across multiple sites to evaluate how patch size and environmental differences can influence the plants that return after Phragmites removal. The treatments (applied over 3 years and monitored two more) compared two different herbicides (glyphosate and imazapyr) and different herbicide and mowing timings. The treatments evaluated in the large patch study were 1.) untreated control 2.) fall glyphosate, winter mow, 3.) summer imazapyr, winter mow, 4.) summer glyphosate, winter mow. The treatments evaluated in the small patch study included treatments 1-4 above plus 5.) summer mow, fall glyphosate, 6.) summer mow, then black plastic solarization. In the small patches, we also monitored the seeds in the soil to assess how Phragmites management treatments can change the densities of Phragmites and native seeds. Fall glyphosate treatments were superior for Phragmites cover reduction. After the initial treatment, summer herbicide and mow treatments reduced Phragmites seed production, while fall glyphosate did not. Phragmites seeds were plentiful in the soil but were reduced following three years of all herbicide treatments. Native plant recovery following Phragmites management was extremely variable across sites. Sites with high soil moisture had better Phragmites removal and more native plants. But when flooding was deep, native plants were rare. Native seed density in the soil did not change due to Phragmites management, but soil seed densities were different across sites, which influenced native plant recruitment. Phragmites was removed more effectively and native plants returned in greater numbers in small patches compared with large. This was because small patches were typically near established native plant communities, which likely provided more native plant seeds and had hydrology that was less disturbed by human activity. In sites where native plants do not return after Phragmites management, practitioners may need to try revegetation with native plant seeds to restore important native plant communities.
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Tibbitts, Spencer A. "Effect of Silicon on Wheat Growth and Development in Drought and Salinity Stress". DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/6925.
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Silicon is a major component of most soils, and is found in significant concentration in plant tissue. Plants vary widely in the amount of silicon they take up, with some plants excluding it, and others using transporters to move the silicon from the soil into their roots. Early plant physiology studies were unable to determine conclusively whether silicon was essential to plant growth, but for some plants, most notably rice, it has proved to be important enough to justify fertilizing silicon deficient fields.
Researchers at the USU Crop Physiology Lab tested the effect of silicon on wheat growth and seed yield components. One study was grown in buckets of peat moss, with half the buckets being stressed with low water. The other study was grown in hydroponic tubs, with half the tubs being stressed with high levels of salt.
The results from these studies showed that silicon does increase wheat seed yield and vegetative mass. Wheat with low levels of silicon exhibited twisting of the awns and decreased roughness of leaf surfaces. Silicon also improved water efficiency of drought stressed plants, and affected the concentration of many micro- and macro-nutrients in leaf tissue.