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1
Liberato, Érica Maria Sauer, Sarita Leonel, Jackson Mirellys Azevedo Souza e Gabriel Maluf Napoleão. "SUBSTRATE MIXING FORMULATIONS FOR CITRUS NURSERY MANAGEMENT". Nativa 9, n. 5 (18 dicembre 2021): 500–507. http://dx.doi.org/10.31413/nativa.v9i5.12777.
Testo completoAbstract (sommario):
The length of citrus seedling development is determined by several factors, including the physical and chemical qualities of the substrate, which affect rootstock growth and, as a result, the quality of field seedlings. The purpose of this study was to see how the ‘Swingle’ citrumelo rootstock developed with different substrate formulations. The experiment was carried out in a seedling nursery from seeding to grafting, and six treatments were carried out, as follows: 60% peat moss, 30% fine grade horticultural vermiculite, 10% rice hulls (1); 60% peat moss, 30% fine grade horticultural vermiculite, 10% rice hulls (2); 50% peat moss, 30% fine grade horticultural vermiculite, 20% rice hulls (3); 50% peat moss, 30% fine grade horticultural vermiculite, 20% rice hulls (4); 50% peat moss, 20% fine grade horticultural vermiculite, 30% rice hulls (5); 50% peat moss, 20% fine grade horticultural vermiculite, 30% rice hulls (6). In addition, the experiment was divided into two stages: seeding (stage 1) and seedling nursery (stage 2). In a completely randomized design, the experiment has six treatments, four replications, and 51 plants per plot. When container transplanting was performed, the emergence percentage of seedlings was determined; thus, eight plants per plot were examined. For the second stage, was used a completely randomized design with 6 substrate formulations, 4 replications, and 20 seedlings per plot. Stem height, stem diameter, leaf number, area meter, root dry matter, leaf and stem dry matter, and quality index were measured on seedlings every 28 days. All substrate formulations improved seedling development until grafting, except for the 30% rice hulls, which hampered seedling development in ‘Swingle' citrumelo.
2
Albrecht, Ute, e Kim D. Bowman. "Candidatus Liberibacter asiaticus and Huanglongbing Effects on Citrus Seeds and Seedlings". HortScience 44, n. 7 (dicembre 2009): 1967–73. http://dx.doi.org/10.21273/hortsci.44.7.1967.
Testo completoAbstract (sommario):
Huanglongbing (HLB) is a devastating disease of citrus and threatens the citrus industry worldwide. The suspected causal agent of the disease is a phloem-limited bacterium of the genus Candidatus Liberibacter transmitted through insect vector or grafting with diseased budwood. Currently, most seed source trees for citrus rootstock propagation are located outdoors and unprotected from disease transmission. In addition, fruit from HLB-affected scion varieties in Florida containing seeds enter the commercial trade and move into other citrus-growing areas. The objective of this study was to determine how Ca. L. asiaticus infection affects seed quality and seedling development and whether the disease appears in seedlings grown from infected fruit. Two experiments were conducted involving thousands of seedlings produced from seeds from infected rootstock seed source trees and ‘Valencia’ sweet orange trees, respectively. Infection of trees and fruit with Ca. L. asiaticus significantly reduced seed weight, seed germination, and seedling height. Seedlings did not develop symptoms typical of HLB throughout the experiment. Polymerase chain reaction (PCR) analysis initially identified two of 686 rootstock seedlings and three of 431 sweet orange seedlings positive for the pathogen when they were very young. Resampling and PCR analysis of these five seedlings at older ages consistently indicated they were negative for the pathogen and none of these plants ever developed symptoms of HLB. It is suggested that Ca. L. asiaticus may have been translocated into some part of the embryo during seed development but that it was not present in cells or tissue, which permitted replication or disease development as the seedling grew.
3
Rieger, Mark. "Growth, Gas Exchange, Water Uptake, and Drought Response of Seedling- and Cutting-propagated Peach and Citrus Rootstocks". Journal of the American Society for Horticultural Science 117, n. 5 (settembre 1992): 834–40. http://dx.doi.org/10.21273/jashs.117.5.834.
Testo completoAbstract (sommario):
Growth, gas exchange, root hydraulic conductivity, and drought response of seedling and rooted cuttings of Lovell and Nemaguard peach [Prunus persica (L.) Batsch], and Carrizo (Poncirus trifoliata × Citrus sinensis) and sour orange (C. aurantium L.) citrus rootstocks were compared to determine the influence of propagation method on these characteristics. Rooted peach cuttings had a higher proportion of root biomass in fibrous roots (≤ mm in diameter) and lower root: shoot ratios than seedlings, although this did not occur in citrus. Net CO2 assimilation (A) was higher for peach seedlings than for cuttings, but similar for `Redhaven' (RH) scions on either seedling- or cutting-propagated rootstocks, suggesting that leaf-associated factors were responsible for differences. As in peach, A was higher for Carrizo seedlings than for cuttings, but A was not affected by propagation method in sour orange. Peach seedlings maintained higher A than cuttings as water potentials declined during short-term soil drying, although in citrus this occurred only for Carrizo. RH scions on either root type exhibited similar declines in A as soil dried, indicating the lack of a rootstock effect. Root hydraulic conductivity (Lp) was similar between seedlings and cuttings of all cultivars when expressed on a length basis. Leaf conductance and osmotic adjustment were similar for RH scions on seedling- or cutting-propogated rootstocks during 45 days of drought stress, indicating the lack of a rootstock effect on long-term stress response.
4
dos Santos, Maria Ângela Cruz Macêdo, Mauricio Antônio Coelho Filho, Francisco José Nunes Modesto, Joseph M. Patt e Marilene Fancelli. "Behavioral Responses of Asian Citrus Psyllid (Hemiptera: Liviidae) to Salinity-Stressed Citrus". Environmental Entomology 50, n. 3 (14 aprile 2021): 719–31. http://dx.doi.org/10.1093/ee/nvab028.
Testo completoAbstract (sommario):
Abstract Most commercial citrus varieties are intolerant of salinity stress, but some rootstocks, such as Rangpur lime, tolerate moderately saline irrigation water. Development of salinity-tolerant citrus may allow for citriculture in semiarid and arid regions where salinity stress is problematic. Because salinity stress influences shoot growth in citrus, we compared the behavioral responses of Asian citrus psyllid, Diaphorina citri Kuwayama, to salinity-stressed versus nonstressed Rangpur lime seedlings. The effects of salinity stress on key physiological processes in the seedlings were also examined. Seedlings in the control group were fertilized with a solution having a salinity of 1.7 dS m−1 while seedlings in the salinity-stressed group were fertilized with a solution having a salinity of 10 dS m−1. The seedlings were exposed to salinity stress for increasing durations (15, 20, or 60 d). Seedlings presented differential physiological responses 15 d after the imposition of salinity stress, and differences in psyllid settling rate on control versus salinity-stressed seedlings were discernable within 1 h following the imposition of salinity stress. The levels of settling, oviposition, and egg survivorship were significantly lower on salinity-stressed versus control seedlings. Olfactometer tests showed that female psyllids preferred the odor from control seedlings, suggesting that the odors of control and salinity-stressed seedlings were different. The results showed that D. citri avoids salinity-stressed seedlings; this suggests the possibility of using moderate salinity stress as a management strategy to minimize psyllid settlement and reproduction and to reduce the spread of huanglongbing, especially in citrus grown in semiarid and arid areas.
5
Dixon, R. K., H. E. Garrett e G. S. Cox. "Carbohydrate Relationships of Citrus jambhiri Inoculated with Glomus fasciculatum". Journal of the American Society for Horticultural Science 113, n. 2 (marzo 1988): 239–42. http://dx.doi.org/10.21273/jashs.113.2.239.
Testo completoAbstract (sommario):
Abstract Root exudation patterns and carbohydrate composition of roots and leaves of Citrus jambhiri Lush, were examined during the period of initial colonization by Glomus fasciculatum (Thaxt.) Gerd. and Trappe. Exudation of reducing sugars and amino acids from seedling roots decreased as soil and root P increased. Comparison of vesicular-arbuscular mycorrhizal (VAM) seedlings to nonmycorrhizal seedlings of similar size and P nutrition revealed root exudation in VAM plants decreased following fungal colonization. Root reducing sugars increased and root starch content decreased in VAM seedlings during the infection process. Following establishment of symbiosis, leaves of VAM seedlings had greater levels of total soluble sugar, sucrose, reducing sugars, and starch relative to nonmycorrhizal controls. Colonization of C. jambhiri roots by VAM fungi apparently alters the balance of carbohydrates within leaves and roots.
6
Sykes, SR. "Effects of seedling age and size on chloride accumulation by juvenile citrus seedlings treated with sodium chloride under glasshouse conditions". Australian Journal of Experimental Agriculture 25, n. 4 (1985): 943. http://dx.doi.org/10.1071/ea9850943.
Testo completoAbstract (sommario):
Chloride accumulation by juvenile citrus seedlings treated with sodium chloride for 56 days, using either nutrient solution culture (50 mM NaCl) or pot culture (75 mM NaCl) techniques under glasshouse conditions, was investigated in relation to seedling age. Ranking of cultivars on the basis of leaf chloride concentrations varied according to the age of seedlings examined. Leaf chloride concentrations of 6-, 5-, 4- and 3-month-old seedlings of eight cultivars examined in solution culture decreased with seedling age and were negatively correlated with seedling dry weight within some cultivars. Cultivar differences in leaf chloride concentrations, which occurred for all age groups, were negatively correlated with shoot growth and seedling dry weight for 5-month-old seedlings only. Leaf chloride concentrations of seedlings treated with NaCl in pot culture also changed with the age of seedlings (5, 17- and 29-monthsold) and varied between cultivars, with significant cultivar x age interactions. The effect of seedling size on chloride accumulation was investigated using nutrient solution culture. Six-month-old seedlings of four varieties were treated with NaCl (50 mM) for 56 days. Two size classes were obtained by growing seedlings at two densities before salt treatment. Small seedlings had greater shoot chloride concentrations than equivalent large seedlings and cultivar ranking, based on shoot chloride concentrations, changed with seedling size. Cultivar differences in leaf chloride concentrations were negatively correlated with seedling growth and dry weight for small seedlings but not for large seedlings. Seedling size had no effect on root chloride concentrations. The results suggest that screening very small seedlings for chloride exclusion is not feasible since rankings based on leaf chloride concentrations did not agree with documented data for grafted trees. There appeared to be a critical or threshold seedling age or size at or above which rankings for shoot chloride accumulation by good chloride excluders were consistent with documented field data. The results are discussed in relation to screening citrus hybrids for chloride exclusion under glasshouse conditions.
7
Bowman, Kim D., Frederick G. Gmitter e Xulan Hu. "Relationships of Seed Size and Shape with Polyembryony and the Zygotic or Nucellar Origin of Citrus spp. Seedlings". HortScience 30, n. 6 (ottobre 1995): 1279–82. http://dx.doi.org/10.21273/hortsci.30.6.1279.
Testo completoAbstract (sommario):
We examined the relationship between seed size and shape in Citrus and the number and type of seedlings produced by individual seeds for each of three citrus cultivars. Seed size and shape were related to the number of seedlings produced and the likelihood of recovering a zygotic seedling. The relationship between seed size and shape and the likelihood of recovering a zygotic seedling most often was connected with weight and thickness of a seed. This relationship might be of sufficient strength to use in some aspects of cultivar development. However, the relationship did not appear strong enough to be of practical value for application in commercial production of purely nucellar rootstock seedlings.
8
Bisi, Rayane Barcelos, Ute Albrecht e Kim D. Bowman. "Seed and Seedling Nursery Characteristics for 10 USDA Citrus Rootstocks". HortScience 55, n. 4 (aprile 2020): 528–32. http://dx.doi.org/10.21273/hortsci14598-19.
Testo completoAbstract (sommario):
Six new hybrid rootstocks, ‘US-1279’, ‘US-1281’, ‘US-1282’, ‘US-1283’, ‘US-1284’, and ‘US-1516’, were released from the U.S. Department of Agriculture (USDA) citrus breeding program to provide improved tree tolerance to huanglongbing (HLB), the most destructive disease facing the citrus industry in the United States and many other parts of the world. Five of these new rootstocks were released based on field performance in trials with the rootstocks propagated by stem cuttings, rather than the traditional propagation using nucellar seedlings. In this study, we evaluated the fruit, seed, and seedling characteristics of these new rootstocks, along with four other USDA rootstocks of commercial importance. The study included a determination of the percentage of true-to-type and off-type seedlings by both plant morphology and simple sequence repeat (SSR) markers. All 10 rootstocks produced an acceptable number of seeds and good seedling emergence from those seeds. The rootstocks ‘Swingle’, ‘US-802’, ‘US-812’, ‘US-1283’, ‘US-1284’, and ‘US-1516’ had a high percentage of true-to-type seedlings and correspondingly good potential to be propagated by seeds. However, no true-to-type plants were observed among seedlings from the rootstocks ‘US-1279’, ‘US-1281’, and ‘US-1282’, indicating that economical seed propagation will be impossible for these cultivars. The 10 SSR marker sets used in this study were observed to easily differentiate the 10 rootstocks studied, and readily distinguished true-to-type and off-type seedlings among progeny from all 10 rootstock clones. This study presents information of significant value for commercial nurseries involved in propagation of citrus rootstocks, and those involved in citrus rootstock breeding and development around the world. We propose the use of these 10 SSR marker sets as readily applicable for accurate identification of most citrus rootstock cultivars and their true-to-type seedlings.
9
Al-Shahwany, Ayyad W., Fatima K. Mohammad e Ropak Tofiq. "Influence Soaking Gibberellin acid on seed germination for Citrus limetta and Citrus limonum and their seedlings growth". Journal of Biotechnology Research Center 8, n. 1 (1 gennaio 2014): 43–49. http://dx.doi.org/10.24126/jobrc.2014.8.1.301.
Testo completoAbstract (sommario):
Study was undertaken to test the effects of soaking seeds Citrus limetta and Citurs limonum in Gibberellic acid (GA3) solutions 0, 100, 500, 1000 mg / L for 24 hours prior on the rate of germination, some morphological characteristics for seedlings also were investigated in this study. Factorial experiment was carried out 4×2×5 in a randomized complete block design with five replicates for each type of seed during the period of March to September 2011. The results showed significant differences in most traits, as it reached the highest percentage of germination for the treatment with 500 mg/l for both types of seeds, while the highest dry and fresh weights of shoot and root, main root length, highest shoot, leaves number and leaf area index were in 1000 mg /l treatment. No significant effect of GA3 treatment on the amount of A, B and total chlorophyll in the seedlings leaves. The best treatment was soaking seed in 1000gm/l Gibberellic acid. The information documented the stimulating effects of seedling be used to increase the ratio of germination. Also gibberellins stimulated effects continues for some seedlings morphological characteristics and progressively with gibberellins seed treatments influence vary according to genotypes of citrus seeds, that can increase concentrations which used in soaking seeds solutions.
10
Anderson, Catalina M., William S. Castle e Gloria A. Moore. "Isozymic Identification of Zygotic Seedlings in Swingle Citrumelo Citrus paradisi × Poncirus trifoliata Nursery and Field Populations". Journal of the American Society for Horticultural Science 116, n. 2 (marzo 1991): 322–26. http://dx.doi.org/10.21273/jashs.116.2.322.
Testo completoAbstract (sommario):
Isozyme analysis was the basis for determining the frequency of occurrence and the characteristics of zygotic plants in Swingle citrumelo seedling populations from various sources of open-pollinated seeds, in a commercial nursery of Swingle citrumelo before and after roguing, and in commercial orchards and rootstock trials where this rootstock was used. Most zygotic seedlings identified by isozyme analysis could be distinguished by careful examination of morphological characteristics. Frequencies of zygotic seedlings varied among seedling populations, but were in the range (≈5% to 10%) found in previous studies. Roguing based primarily on size and growth habit of seedlings was effective in removing some, but not all, zygotic seedlings. Most of the remaining zygotic plants in the rogued population were found among the smaller seedlings. Trees budded on zygotic rootstock seedlings were found in two of the three groves studied, and in some instances an apparent incompatibility was developing in young trees.
11
Williamson, Jeffrey G., Karen E. Koch e William S. Castle. "CITRUS ROOTSTOCK SHOOTS ENHANCE SCION GROWTH AFTER BUD FORCING". HortScience 25, n. 9 (settembre 1990): 1152d—1152. http://dx.doi.org/10.21273/hortsci.25.9.1152d.
Testo completoAbstract (sommario):
Carrizo citrange [Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.] seedlings were budded with `Hamlin' orange [Citrus sinensis (L.) Osb.] and subjected to 3 bud forcing treatments: (1) topping [T] by removing the seedling above the bud union; (2) lopping [L] by cutting half way through the seedling above the bud union and breaking the rootstock over; or, (3) bending [B] the seedling top over and tying it to the base of the plant. As scion buds emerged and grew, plants were sacrificed for dry weight measurements; also, the portion of the rootstock seedling above the bud union was exposed to 14CO2 at 3 stages of scion development. Plants with seedling tops attached (B,L) gained more dry weight and fibrous roots than T seedlings. Scion elongation was greater for B plants than for T plants. Plants usually flushed twice regardless of bud forcing treatment. No treatment differences were noted for time of flushing or scion bud emergence. Labeled photosynthate from attached rootstock leaves was translocated to scions during both flushes suggesting that recently fixed C enhanced scion growth for B and L plants.
12
Bamisile, Bamisope Steve, Komivi Senyo Akutse, Chandra Kanta Dash, Muhammad Qasim, Luis Carlos Ramos Aguila, Hafiza Javaria Ashraf, Wei Huang, Mubasher Hussain, Shiman Chen e Liande Wang. "Effects of Seedling Age on Colonization Patterns of Citrus limon Plants by Endophytic Beauveria bassiana and Metarhizium anisopliae and Their Influence on Seedlings Growth". Journal of Fungi 6, n. 1 (25 febbraio 2020): 29. http://dx.doi.org/10.3390/jof6010029.
Testo completoAbstract (sommario):
The inoculation methods, the fungal strains, and several other factors are known to influent the success of fungal entomopathogens colonization in plants. The physiological status of the plant could also be another determinant. In the present study, the ability of three strains of Beauveria bassiana and one strain of Metarhizium anisopliae to successfully colonize Citrus limon plants and the influence of seedling age on endophytic colonization success was examined. Three, 4, and 6 months old seedlings were inoculated with 10 mL of 1 × 108 conidial·mL−1 suspensions of each of the four fungal strains via foliar spraying. All fungal strains successfully colonized citrus seedlings and were sustained up to 2 months in colonized plants irrespective of the seedling age, with differences in the mean percentage colonization recorded at various post-inoculation periods among the fungal strains. The highest percent endophytic fungi recovery rate was recorded in the 3 months old seedlings, where fungal mycelia of inoculated fungi were successfully re-isolated from 65.6% of the untreated newly developed leaf and stem tissues. One strain of B. bassiana, BB Fafu-12, significantly improved seedling height and leaf number. The study demonstrates the influence of seedling age on B. bassiana and M. anisopliae successful colonization in the citrus plant.
13
Snowball, Angela M., Elizabeth A. Halligan, I. J. Warrington e M. G. Mullins. "Phase change in citrus: Growth and flowering of citrus seedlings from thirteen genetically diverse seedling families". Journal of Horticultural Science 69, n. 1 (gennaio 1994): 141–48. http://dx.doi.org/10.1080/14620316.1994.11515260.
Testo completo
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Singh, Megh, e Wondimagegnehu Mersie. "Metalaxyl Toxicity to Citrus with or without Herbicides". Weed Technology 7, n. 2 (giugno 1993): 511–14. http://dx.doi.org/10.1017/s0890037x00027962.
Testo completoAbstract (sommario):
The response of potted ‘Cleopatra’ mandarin citrus seedlings to metalaxyl applied as a mixture with metolachlor, simazine, or bromacil, or as a sequential application after the herbicides was investigated under screen house conditions. The soils were drenched with herbicides at 2.5 ppmw (mg kg−1 soil dry wt basis) in tank-mixes with metalaxyl or metalaxyl was applied as a soil drench at 5, 50, and 250 ppmw 1, 2, 3, and 4 wk after herbicide application. Citrus seedling response to treatment was dependent on the presence or absence of herbicide, metalaxyl concentration, and the time following application. Fresh weights of citrus treated with 5 ppmw metalaxyl after herbicide application were no different from those treated with the mixture. Metalaxyl at 5 and 50 ppmw alone or with metolachlor did not affect citrus seedling fresh weight. However, delaying metalaxyl application at 50 ppmw by 3 or 4 wk after simazine and bromacil increased citrus seedling fresh weight as compared with the tank-mix. Separate applications of metalaxyl at 250 ppm reduced citrus seedling fresh weight less than the mixture for all the herbicides.
15
Rouse, Robert E. "Controlling Citrus Rootstock Sprouting in the Nursery Using Commercially Available NAA". HortScience 30, n. 4 (luglio 1995): 888F—888. http://dx.doi.org/10.21273/hortsci.30.4.888f.
Testo completoAbstract (sommario):
Tre-Hold, a commercially available sprout inhibitor containing ethylnaphthaleneacetate (NAA) for newly planted citrus trees in orchards was effective to prevent axillary bud growth on rootstock seedlings in the nursery. Tre-Hold applied at formulated concentration (1×), three-fourths (3/4×), and one-half (1/2×) to field-grown and container-grown greenhouse seedlings prevented sprouting. It was possible to control dormancy of individual buds without affecting adjacent buds. When applied to green citrus tissue, no phytotoxicity occurred. Full concentration of Tre-Hold was found to prevent scion bud healing of container-grown trees when the seedling was treated before budding. Application a few days before unwrapping and after the scion bud had healed did not affect bud healing or budling growth.
16
Eissenstat, David M., Javier F. Espeleta e Eric L. Whaley. "Responses of the Fine Roots of Citrus to Dry Surface Soil". HortScience 31, n. 4 (agosto 1996): 577a—577. http://dx.doi.org/10.21273/hortsci.31.4.577a.
Testo completoAbstract (sommario):
Despite the frequent occurrence of hot, dry surface soil, little is known about the fate of roots in this soil layer during and following periods of surface drought. Phosphorus uptake kinetics were examined in surface roots of citrus seedlings exposed to different periods of drought. Exposure to dry soil for up to 43 days had no effect on phosphate uptake of excised roots measured at solution concentrations of 50, 750, and 1500 μm phosphate. Effects of surface drought on fine root behavior of seedlings and bearing trees were examined in the field using a split-pot arrangement. At the end of 5 weeks of drought, only about 1% of the roots in the top pot of either the seedling or tree had died. By 8 to 9 weeks of drought, about 26% of the fine laterals of the adult citrus had died, but only 6% had died in the seedling. After 15 weeks of drought, 33% of the mature tree fine roots had died but only 8% had died in the seedling. Root-soil respiration per gram root at this time was at least twice as high in the seedling as in the mature tree. Fine roots of citrus are remarkably tolerant to dry surface soils of about 5 weeks duration, both in terms of root survival and resumption of physiological activity after rewetting.
17
Reddy, Krishna N., e Megh Singh. "Response of Citrus (Citrus spp.) Rootstock Seedlings to Soil-Applied Herbicides". Journal of Environmental Horticulture 11, n. 1 (1 marzo 1993): 39–40. http://dx.doi.org/10.24266/0738-2898-11.1.39.
Testo completoAbstract (sommario):
Abstract A greenhouse study was conducted to evaluate the response of Carrizo citrange [Citrus sinensis (L.) Obs. × Poncirus trifoliata (L.) Raf.], Cleopatra mandarin (C. reticulata Blanco), sour orange (C. aurantium L.), and Swingle citrumelo [C. paradisi Macf. × P. trifoliata (L.) Raf.] citrus rootstock seedlings to multiple applications of Premier (fluometralin), Dual (metolachlor), Devrinol (napropamide), Solicam (norflurazon), Surflan (oryzalin), Prowl (pendimethalin), and Treflan trifluralin). The citrus rootstock responses ranged from a 11% reduction in shoot weight of sour orange with Treflan (trifluralin) to a 19% reduction in fibrous root weight of Swingle citrumelo with Surflan (oryzalin). Cleopatra mandarin was tolerant to all the seven herbicides. Dual (metolachlor), Devrinol (napropamide), Solicam (norflurazon), and Premier (fluometralin) were not phytotoxic to all four rootstocks.
18
Peres, Natália A. R., Soonho Kim, Howard W. Beck, Nilton L. Souza e Lavern W. Timmer. "A Fungicide Application Decision (FAD) Support System for Postbloom Fruit Drop of Citrus (PFD)". Plant Health Progress 3, n. 1 (gennaio 2002): 16. http://dx.doi.org/10.1094/php-2002-0731-01-rv.
Testo completoAbstract (sommario):
Surveys were conducted to identify fungi associated with postemergence cotton seedling disease in Missouri. Samples consisted of 10 cotton seedlings, 2 to 3 weeks after emergence, with symptoms of seedling diseases collected from a 0.25 ha area in each of 60 fields in 1997 and 1998. Four genera of fungi were cultured from the roots (Fusarium, Pythium, Rhizoctonia, and Thielaviopsis) and three species were identified: Rhizoctonia solani, Thielaviopsis basicola, and Pythiumultimum. Rhizoctonia solani, T. basicola, and P. ultimum were cultured from seedlings in 70%, 47%, and 15% of fields sampled in 1997, respectively, and 55%, 17%, and 5% of fields sampled in 1998, respectively. Repeated tests of pathogenicity confirmed that R. solani AG-4, T. basicola, and P. ultimum were major causal agents of postemergence cotton seedling disease in Missouri. This study provides the first documentation on the distribution and frequency of fungi associated with postemergence seedling disease complex of cotton based on a survey of randomly selected fields. Accepted for publication 10 July 2002. Published 31 July 2002.
19
Vashisth, Tripti, Changpin Chun e Monica Ozores Hampton. "Florida Citrus Nursery Trends and Strategies to Enhance Production of Field-Transplant Ready Citrus Plants". Horticulturae 6, n. 1 (1 febbraio 2020): 8. http://dx.doi.org/10.3390/horticulturae6010008.
Testo completoAbstract (sommario):
The Florida citrus industry is going through major changes and considerable replanting. Many growers are planting varieties, especially rootstocks, that are potentially productive under Huanglongbing (HLB; Candidatus Liberibacter asiaticus) prevalent conditions. However, the high demand for new plant material has put tremendous pressure on citrus nurseries and has created a bottleneck in production. Often it can take more than one year to produce field-transplant ready plants in nurseries; therefore, there is a critical need to accelerate plant production. This three-part study was conducted with the following objectives: (1) determine citrus nursery trends; (2) evaluate use of compost for rootstock germination; and, (3) evaluate use of compost for rootstock seedling growth. According to the nursery survey, rootstock seed germination and seedling growth were the most time-consuming, taking 6–8 months. Moreover, it was apparent from the survey results that 44% of the citrus nurseries were experimenting with potting mixes to achieve adequate plant growth and quality. Our greenhouse study demonstrated successful use of yard waste compost in place of peat moss in a potting mix. With use of 37% to 50% of compost in the potting mix, the overall germination rate and mean emergence time were improved to 70% in less than four weeks for US-897 rootstock as compared to no compost in the potting mix. In addition, 37% to 50% compost resulted in higher biomass accumulation in seedlings. When seedlings of rootstocks C-32 and Flying Dragon were grown with 37% to 50% compost, the growth rate and, therefore, percentage of successful budding were significantly increased as compared to no compost. In addition, substrate analysis indicated that a high compost potting media was rich in mineral nutrients, hence the use of fertilizer in nurseries could be minimized. Altogether, use of compost in place of peat moss seems promising and could accelerate germination and growth of rootstocks, reducing the production time as well as cost.
20
Oiyama, Iwao, e Shozo Kobayashi. "Citrus Pentaploids from Small Seeds of Diploid × Diploid Crosses". HortScience 26, n. 3 (marzo 1991): 292–93. http://dx.doi.org/10.21273/hortsci.26.3.292.
Testo completoAbstract (sommario):
Seedlings from some small seeds of diploid × diploid crosses using `Miyauchi iyokan' (Citrus iyo Hort. ex Tanaka) as the seed parent were found to be pentaploid (2n = 5x = 45). The growth of pentaploid seedlings was extremely weak on their own roots, but was much more vigorous when micrografted on seedlings of tetraploid trifoliate orange [Poncirus trifoliata (L.) Raf.]. Diploid `Miyauchi iyokan' produced hexaploid seedlings from small seeds in addition to triploid and tetraploid seedlings from normal seeds when crossed with tetraploid `Funadoko' (C. funadoko Hort. ex Y. Tanaka) and `Trovita' sweet orange [C. sinensis (L.) Osbeck]. Based on this phenomenon, the origin of pentaploids is discussed.
21
Albrecht, Ute, e Kim D. Bowman. "Tolerance of the Trifoliate Citrus Hybrid US-897 (Citrus reticulata Blanco × Poncirus trifoliata L. Raf.) to Huanglongbing". HortScience 46, n. 1 (gennaio 2011): 16–22. http://dx.doi.org/10.21273/hortsci.46.1.16.
Testo completoAbstract (sommario):
Huanglongbing (HLB) is a destructive disease of citrus in most citrus-producing countries worldwide. The disease, presumably caused by phloem-limited bacteria of the genus Candidatus Liberibacter, affects all known citrus species and citrus relatives with little known resistance. Typical disease symptoms are the production of abnormal-looking fruit and chlorosis or blotchy mottle of the leaves followed at advanced stages by tree decline and death. Trifoliate orange (P. trifoliata L. Raf.) and some of its hybrids reportedly lack distinct disease symptoms despite infection with the pathogen. US-897 is a hybrid of trifoliate orange and ‘Cleopatra’ mandarin (C. reticulata Blanco), the latter being highly susceptible to HLB. This study investigated whether field-grown, naturally infected trees and greenhouse-grown, graft-inoculated seedlings of this genotype display tolerance or resistance to HLB. It was shown that naturally infected US-897 trees exhibited no distinct disease symptoms commonly associated with HLB, except for the occurrence of few mottled leaves in a small percentage of trees. Analysis of fruit and seed from infected trees did not detect any growth reduction or otherwise negative impact on development. Graft-inoculated US-897 seedlings became polymerase chain reaction (PCR)-positive for the pathogen but exhibited a superior performance compared with ‘Cleopatra’ mandarin seedlings, which displayed severe disease symptoms soon after inoculation. Despite infection, most US-897 seedlings did not develop leaf symptoms typical for HLB. Foliar symptoms observed in a small number of plants at later stages of the disease were faint and difficult to discern. Contrary to ‘Cleopatra’ seedlings, growth in stem diameter was only moderately reduced or unaffected in infected US-897 seedlings. The superior performance of US-897 plants in greenhouse and field locations suggest tolerance of this genotype to Ca. L. asiaticus.
22
Scholberg, J. M. S., L. R. Parsons e T. A. Wheaton. "507 Nitrogen Uptake Dynamics of Citrus Seedlings". HortScience 35, n. 3 (giugno 2000): 482B—482. http://dx.doi.org/10.21273/hortsci.35.3.482b.
Testo completoAbstract (sommario):
Improving our understanding of processes that control and limit nitrogen uptake by citrus can provide a scientific basis for enhancing nitrogen fertilizer use efficiency. Nitrogen uptake dynamics of two rootstock seedlings will be compared to those of young budded trees. Three-month old Swingle citrumelo [Citrus paradisi Macf. × Poncirus trifoliata (L.) Raf.] and Volkamer lemon (C. volkameriana Ten. & Pasq.) trees were planted in PVC columns filled with a Candler fine sand. Field experiments were conducted using 4-year-old `Hamlin' orange trees [Citrus sinensis (L.) Osb.] grafted on `Carrizo' [C. sinensis × Poncirus trifoliata (L.) Raf.] or on Swingle citrumelo. Trees were either grown in solution culture using 120-L PVC containers or in 900-L PVC tubs filled with a Candler fine sand. Additional trees were planted in the field during Spring 1998. Two lateral roots per tree were trained to grow in slanted, partly burried, 20-L PVC columns filled with a Candler fine sand. Nitrogen uptake from the soil was determined by comparing the residual N extracted by intensive leaching from planted units with that of non-planted (reference) units. With the application of dilute N solutions (7 mg N/L), plants reduced N concentrations to near-zero N concentrations within days. Applying N at higher concentrations (70 or 210 mg N/L) resulted in higher initial uptake rates, increased residual soil N levels, and reduced nitrogen uptake efficiency. Contributions of passive uptake to total nitrogen uptake ranged from less than 5% at soil solution concentrations around 3 ppm N to 20% to 30% at concentrations of 60 ppm N.
23
FONSECA, ANTONIO EDUARDO, BRUNO DE MORAES NUNES e JOÃO BATISTA FERREIRA JÚNIOR. "TENACITY AND PERSISTENCE OF COPPER FUNGICIDES IN CITRUS SEEDLINGS UNDER SIMULATED RAINFALL". Revista Caatinga 29, n. 3 (settembre 2016): 677–84. http://dx.doi.org/10.1590/1983-21252016v29n318rc.
Testo completoAbstract (sommario):
ABSTRACT The amount of fungicide that adheres to the leaf during spraying and the amount that remain on the leaf after weathering are the main factors that defines the amount of active residue on the leaf surface to effectively control plant pathogens. Thus, the objective of this work was to evaluate the tenacity and persistence of copper in citrus seedling leaves under simulated rainfall in Jaboticabal, State of São Paulo, Brazil. The evaluated variables were copper content, solution retention, surface tension and drop spectrum. A significant and inversely proportional linear relationship to drops <100 µm was found. The percentage of copper retained in leaves of citrus seedlings with copper fungicides of suspension concentrate (SC) formulations after simulated rainfall was greater than 80%. Copper fungicides of SC formulations presented the lowest surface tension, allowing greater tenacity and persistence of copper on seedlings of citrus leaves after simulated rainfall and increased contact between the drops and leaf surface.
24
GAFNY, R., N. MOGILNER, Y. NITZAN, J. BEN-SHALOM e M. BAR-JOSEPH. "The movement and distribution of citrus tristeza virus and citrus exocortis viroid in citrus seedlings". Annals of Applied Biology 126, n. 3 (giugno 1995): 465–70. http://dx.doi.org/10.1111/j.1744-7348.1995.tb05381.x.
Testo completo
25
Baron, Daniel, Gisela Ferreira, Carmen Sílvia Fernandes Boaro e Martha Maria Mischan. "Evaluation of substrates on the emergence of "araticum-de-terra-fria" (Annona emarginata (Schltdl.) H. Rainer) Seedlings". Revista Brasileira de Fruticultura 33, n. 2 (27 maggio 2011): 575–86. http://dx.doi.org/10.1590/s0100-29452011005000053.
Testo completoAbstract (sommario):
Choosing a substrate is the determinant factor for the seedling producer; thus, the aim of this study was to evaluate the effect of different types of substrates on the emergence of "araticum-de-terra-fria" (Annona emarginata (Schltdl.) H. Rainer) seedlings. The experiment was carried out in a greenhouse and the experimental design was in randomized blocks, with three treatments and five replicates of 72 seeds per plot. The treatments consisted of the following substrates: coconut fiber, vermiculite and Plantmax® Citrus. The number of emerged seedlings was weekly counted for 105 days. Data regarding seedling height were obtained, and the emergence velocity index and mean time, besides total emergence percentage and that over time were calculated. Results from total mean emergence percentage, seedling height, emergence velocity index (EVI), and mean emergence time (MET) were subjected to analysis of variance and means were compared by the Tukey's test at 5% significance. The curves concerning the emergence percentage over time were fit by the logistic growth equation for each treatment and the means of each parameter (A, B, C) were compared by the Duncan's test at 5% significance. The substrates vermiculite led to the highest values of emergence percentage differing from the PlantMax® Citrus, but not of the coconut fiber, however the vermiculite promoted seedling height in a shorter time; therefore, this substrate is recommended for the initial development of "araticum-de-terra-fria" (Annona emarginata (Schltdl.) H. Rainer) seedlings.
26
Wu, Q. S., Y. N. Zou, W. Liu, X. F. Ye, H. F. Zai e L. J. Zhao. "Alleviation of salt stress in citrus seedlings inoculated with mycorrhiza: changes in leaf antioxidant defense systems". Plant, Soil and Environment 56, No. 10 (20 ottobre 2010): 470–75. http://dx.doi.org/10.17221/54/2010-pse.
Testo completoAbstract (sommario):
Citrus is a salt-sensitive plant. In the present study, the salt stress ameliorating the effect of arbuscular mycorrhizal fungi through antioxidant defense systems was reported. Three-month-old trifoliate orange (Poncirus trifoliata) seedlings colonized by Glomus mosseae or G. versiforme were irrigated with 0 and 100 mmol NaCl solutions. After 49 days of salinity, mycorrhizal structures were obviously restrained by salt stress. Mycorrhizal inoculation especially G. mosseae significantly alleviated the growth reduction of salinity. There were notably lower malondialdehyde and hydrogen peroxide contents in the leaves of mycorrhizal seedlings than in non-mycorrhizal ones. Mycorrhizal seedlings recorded notably greater activity of catalase and contents of ascorbate, soluble protein and glutathione under salinity or non-salinity conditions. The seedlings colonized by G. mosseae showed significantly higher antioxidant defense systems response to salinity than by G. versiforme. Our data demonstrate that mycorrhizal (especially G. mosseae) citrus seedlings exhibited greater efficient antioxidant defense systems, which provide better protection against salt damage.
27
Singh, Jagveer, Harvinder Singh Dhaliwal, Anirudh Thakur, Gurupkar Singh Sidhu, Parveen Chhuneja e Frederick G. Gmitter. "Optimizing Recovery of Hybrid Embryos from Interspecific Citrus Crosses of Polyembryonic Rough Lemon (Citrus jambhiri Lush.)". Agronomy 10, n. 12 (10 dicembre 2020): 1940. http://dx.doi.org/10.3390/agronomy10121940.
Testo completoAbstract (sommario):
The prevalence of rough lemon rootstock in India is presently threatened by the spread of Phytophthora root rot. Developing an alternative Phytophthora-resistant rootstock that also withstands other abiotic constraints is a priority for a sustainable citrus industry in India. Complementary progenitors can be found in citrus germplasm to combine the desired traits, particularly between Citrus and Poncirus, a closely related genus. The production of hybrids accumulating the desired dominant traits, irrespective of the heterozygosity level of the parents, is an effective way to develop new candidate rootstocks. Rough lemon was hybridized with Swingle citrumelo, X-639 citrandarin, and GouTou Cheng. A reliable method was developed for greater recovery of hybrid seedlings from these crosses on the basis of morphology and simple sequence repeat (SSR) markers. The greatest proportion of hybrid seedlings resulted from embryo rescue at 95 days after pollination (DAP) (48.5% in rough lemon × X-639 citrandarin and 56.7% in rough lemon × Swingle citrumelo) on the basis of multifoliate leaves. The proportion of hybrid seedlings decreased with increase in embryo development stage after 95 DAP until the last stage of observation (125 DAP). Significantly higher proportion of multifoliate seedlings was recovered by in vitro culture compared with in vivo germination from the mature seeds (26.9% vs. 5.2%, respectively). Swingle and X-639 citrandarin are not homozygous for the multifoliate allele from Poncirus, and GouTou Cheng lacks the multifoliate allele; thus, unifoliate hybrids were selected from all crosses on the basis of SSR marker genotypes.
28
Marques, Léo O. D., Paulo Mello-Farias, Roberto P. de Oliveira, Maximiliano Dini, Walter S. Soares Filho e Marcelo B. Malgarim. "Emergence Percentage and Speed of Rootstocks for Citriculture in South of Brazil". Journal of Agricultural Science 11, n. 5 (15 aprile 2019): 49. http://dx.doi.org/10.5539/jas.v11n5p49.
Testo completoAbstract (sommario):
The fact that Brazilian citriculture has focused on few rootstocks poses several phytosanitary risks to the culture and has made genetic improvement programs develop hybrid genotypes to be used as novel alternatives. This study aimed at evaluating the behavior of 42 different rootstocks regarding their emergence percentage and speed in weather conditions experienced in the extreme south of Brazil. Seeds of hybrids developed by the Citrus Genetic Improvement Program (PMG Citros) at the Embrapa Mandioca e Fruticultura (PMG Citros) and cultivars from other citrus growing regions were sown in conical tubes filled with commercial substrate in May 2017. A thoroughly randomized design with 4 replicates, each composed of 45 sampling units, was employed. Emergence percentage and emergence speed of every genotype were evaluated and the ones with the highest emergence percentage of seedlings and the ones with the most precocious emergence were identified. All genotypes completed seedling emergence 98 days after sowing. Seeds of Trifoliata, TSKC × CTSW-041 and TSKC × CTSW-025 had the highest values of seedling emergence whereas the highest emergence speed indexes were exhibited by genotypes Trifoliata and lemon tree ‘Cravo’.
29
Sorgonà, A., e G. Cacco. "Linking the physiological parameters of nitrate uptake with root morphology and topology in wheat (Triticum durum) and citrus (Citrus volkameriana) rootstock". Canadian Journal of Botany 80, n. 5 (1 maggio 2002): 494–503. http://dx.doi.org/10.1139/b02-029.
Testo completoAbstract (sommario):
The relationships between net nitrate uptake and root morphology and topology were investigated in wheat (Triticum durum Desf.) and citrus (Citrus volkameriana Ten. & Pasq.) seedlings in which root systems were modified by supplying different nutrient concentrations. Root morphological and topological changes were assessed by the number of root tips, the total root length, and the topological index. The net nitrate uptake process was evaluated during the induction and inhibition "feedback" regulation phases. In wheat seedlings, an increase in the external nitrate concentration, at either high or no phosphate, brought about an increase in number of root tips but did not affect total root length. A similar pattern was observed in citrus seedlings. Citrus seedlings also exhibited a shift in root branching pattern from herringbone to dichotomous with an increase in the external nitrate concentration. Conversely, wheat root topology was unaffected by nutrient treatments. A high level of nitrate supplied to wheat and citrus root systems reduced the full induction of the nitrate uptake rate and cumulative nitrate uptake but increased the half-time of reaching the full induction in net nitrate uptake (t1/2 kind). Finally, a negative correlation between number of root tips and t1/2 kind was found in both species, while only in citrus seedlings was a positive correlation between t1/2 kind and the topological index observed. The data suggest that root morphology has a greater effect on nitrate uptake than root topology.Key words: root morphology, root topology, net nitrate uptake, Citrus volkameriana, Triticum durum.
30
Hilf, Mark E. "Colonization of Citrus Seed Coats by ‘Candidatus Liberibacter asiaticus’: Implications for Seed Transmission of the Bacterium". Phytopathology® 101, n. 10 (ottobre 2011): 1242–50. http://dx.doi.org/10.1094/phyto-11-10-0323.
Testo completoAbstract (sommario):
Huanglongbing is an economically damaging disease of citrus associated with infection by ‘Candidatus Liberibacter asiaticus’. Transmission of the organism via infection of seeds has not been demonstrated but is a concern since some citrus varieties, particularly those used as rootstocks in commercial plantings are propagated from seed. We compared the incidence of detection of ‘Ca. Liberibacter asiaticus’ DNA in individual fruit peduncles, seed coats, seeds, and in germinated seedlings from ‘Sanguenelli’ sweet orange and ‘Conners’ grapefruit fruits sampled from infected trees. Using real-time quantitative PCR (qPCR) we detected pathogen DNA in nucleic acid extracts of 36 and 100% of peduncles from ‘Sanguenelli’ and from ‘Conners’ fruits, respectively. We also detected pathogen DNA in extracts of 37 and 98% of seed coats and in 1.6 and 4% of extracts from the corresponding seeds of ‘Sanguenelli’ and ‘Conners’, respectively. Small amounts of pathogen DNA were detected in 10% of ‘Sanguenelli’ seedlings grown in the greenhouse, but in none of 204 extracts from ‘Conners’ seedlings. Pathogen DNA was detected in 4.9% and in 89% of seed coats peeled from seeds of ‘Sanguenelli’ and ‘Conners’ which were germinated on agar, and in 5% of ‘Sanguenelli’ but in none of 164 ‘Conners’ seedlings which grew from these seeds on agar. No pathogen DNA was detected in ‘Ridge Pineapple’ tissue at 3 months post-grafting onto ‘Sanguenelli’ seedlings, even when pathogen DNA had been detected initially in the ‘Sanguenelli’ seedling. Though the apparent colonization of ‘Conners’ seeds was more extensive and nearly uniform compared with ‘Sanguenelli’ seeds, no pathogen DNA was detected in ‘Conners’ seedlings grown from these seeds. For either variety, no association was established between the presence of pathogen DNA in fruit peduncles and seed coats and in seedlings.
31
Cheng, Frank Suozhan, e Mikeal L. Roose. "Origin and Inheritance of Dwarfing by the Citrus Rootstock Poncirus trifoliata `Flying Dragon'". Journal of the American Society for Horticultural Science 120, n. 2 (marzo 1995): 286–91. http://dx.doi.org/10.21273/jashs.120.2.286.
Testo completoAbstract (sommario):
`Flying Dragon' Poncirus trifoliata L. Raf. is a dwarfing rootstock for citrus. Inheritance of dwarfing ability was studied in a population of open-pollinated seedlings of `Flying Dragon'. Molecular marker genotypes suggest that all seedlings originated from selfing. Progeny seedlings were budded with `Cutter Valencia' orange and planted in the field to evaluate the dwarfing effect of the seedling rootstock. At 5 years after planting, rankit analysis of the frequency distributions of trunk cross-sectional area and canopy volume suggested the presence of two overlapping distributions of 34 dwarf trees and 7 nondwarf. This ratio is consistent with inheritance of rootstock dwarfing as a single dominant gene for which `Flying Dragon' is heterozygous. Two morphological characteristics of `Flying Dragon', curved thorns and twisted trunk growth, were closely linked to, or pleiotropic effects of, the dwarfing gene. Bulked segregant analysis was used to identify three RAPD markers linked to the dwarfing gene. `Flying Dragon' was identical to nondwarfing cultivars of trifoliate orange at 40 homozygous and heterozygous isozyme and RFLP markers; therefore, it is likely that `Flying Dragon' originated as a mutant of a nondwarfing genotype and has not undergone sexual recombination since this event.
32
Tignor, Milton E., e Peter J. Stoffella. "595 Computer Root Image Analysis of Citrus Rootstock Seedlings". HortScience 35, n. 3 (giugno 2000): 499D—499. http://dx.doi.org/10.21273/hortsci.35.3.499d.
Testo completoAbstract (sommario):
Florida citrus has had an average annual on-tree-value of ≈1 billion dollars during the past decade in Florida. Nearly all of the 845,260 acres of citrus in Florida is produced on grafted trees consisting of a commercial scion cultivar and a rootstock selected specifically for local soil, environment, and pest pressures. With vastly different root-zone environments, ranging from deep sands to drained and cleared pine Flatwoods, a large number of different rootstocks are utilized. These rootstocks are started from seed at more than 100 commercial nurseries statewide, which currently produce an estimated 6 million trees a year. Although the optimum germination conditions, basic physiological performance, and adaptability of many rootstocks are known, there has been minimal investigation on early root development in seedling trays at the nursery. Four hundred seedlings of `Swingle' citrumelo (Citrus paradisi Macf. `Dunacn' × Poncirus trifoliata), `Smooth Flat Seville', `Volkamer' lemon (Citrus volkameriana), and `Sun Chu Sha' mandarin were seeded in a randomized block experimental design and grown at a commercial nursery. Seedling root systems (100/rootstock) were analyzed for a number of variables using the Rhizo (Regent Instruments, Inc.) software package and a dual light source scanner. Using the SAS general linear model procedure, hypothesis testing revealed rootstock selection had a significant effect on total root length, total root surface area, total root volume, number of root tips, number of root forks, root dry weight, and stem diameter. For most characteristics, rootstock genotype accounted for a greater portion of variability than samples (plant to plant variability).
33
Widmer, T. L., J. H. Graham e D. J. Mitchell. "Composted Municipal Waste Reduces Infection of Citrus Seedlings by Phytophthora nicotianae". Plant Disease 82, n. 6 (giugno 1998): 683–88. http://dx.doi.org/10.1094/pdis.1998.82.6.683.
Testo completoAbstract (sommario):
Most citrus nurseries and orchards in Florida are infested with Phytophthora nicotianae, the causal agent of Phytophthora root rot. Although fungicides control the disease and increase seedling growth and tree yields, they are not always economically or environmentally sustainable. Amendment of citrus soils with composted municipal waste (CMW) may provide an alternative to fungicides for disease management. Citrus seedling growth decreased with increasing proportions of one CMW source, indicating the potential for phytotoxicity from soluble salts and acetic acid when the proportion of CMW in soil exceeded 20% (vol/vol). When a citrus soil was amended (20% vol/vol) with certain sources of CMW, the incidence of infection of 5-week-old susceptible citrus seedlings by P. nicotianae was reduced from 95% to as low as 5%. Addition of fresh CMW to two different citrus soils reduced colony growth of P. nicotianae after the fungus was incubated in the amended soil for 6 days and then recovered on PARPH selective medium. If CMW was stored for more than 3 months before amendment, the soil mixtures did not suppress colony development. In general, extracts of fresh CMW reduced mycelial growth in vitro; whereas suppressiveness of CMW from the same batch was lost after storage. Acetic acid was detected at higher concentration in fresh CMW that suppressed colony growth than in CMW that lacked activity. A species of Acremonium was isolated from another source of CMW that was suppressive to P. nicotianae. This fungus parasitized hyphae of P. nicotianae in vitro. Thus, CMWs have the potential to at least temporarily suppress P. nicotianae through chemical and microbial agents depending on source and age of the CMW.
34
Krueger, Robert R., e Mikeal L. Roose. "Use of Molecular Markers in the Management of Citrus Germplasm Resources". Journal of the American Society for Horticultural Science 128, n. 6 (novembre 2003): 827–37. http://dx.doi.org/10.21273/jashs.128.6.0827.
Testo completoAbstract (sommario):
New potential citrus germplasm accessions may be received as seed rather than budwood, thereby reducing phytosanitary risks. However, trueness-to-type may be an issue with seed materials because many varieties produce both apomictic (nucellar) and sexual (zygotic) embryos and most citrus is fairly heterozygous. To identify nucellar seedlings of polyembryonic types and to retain these as representing the type, we screened 1340 seedlings from 88 seed sources for markers amplified with two inter-simple sequence repeat (ISSR) primers. Sixteen seed sources produced no seedlings classified as being of nucellar origin. Among the remaining seed sources, seedlings classed as nucellar were identified for potential addition to the collection. In 37 accessions, both nucellar and zygotic seedlings were detected, and in some cases both types were retained. Inclusion of established accessions of the same cultivar group in the analysis allowed an initial assessment of similarity to existing accessions. This technique improved the efficiency of acquiring new germplasm of polyembryonic types by seed. The method identifies those seed sources that produce few or no nucellar seedlings, but it is not useful for determining which seedlings of monoembryonic types should be retained in collections.
35
Gonzalez, Pedro, James P. Syvertsen e Ed Etxeberria. "Sodium Distribution in Salt-stressed Citrus Rootstock Seedlings". HortScience 47, n. 10 (ottobre 2012): 1504–11. http://dx.doi.org/10.21273/hortsci.47.10.1504.
Testo completoAbstract (sommario):
Although citrus trees are considered relatively salt-sensitive, there are consistent differences in Na+ and Cl– tolerance among different citrus rootstocks. We grew uniform seedlings of rough lemon (RL) and the more Na+-tolerant Swingle citrumelo (SC) with and without 50 mm NaCl for 42 days. Salinity reduced leaf chlorophyll and plant transpiration rate (Ep) more in RL than SC. Confocal laser scanning analyses using the Na+-specific cell-permeant fluorescent probe CoroNa-Red revealed a higher capacity for Na+ sequestration in root tissue vacuoles of SC than in RL roots and that cell walls within the stele acted as Na+ traps. In leaves, however, RL had significantly higher Na+-dependent fluorescence than SC. Thus, the sequestration of Na+ in root tissue vacuoles and its immobilization by cell walls were key contributing mechanisms enabling SC leaves to maintain lower levels of Na+ than RL leaves. Examination of intracellular distribution of CoroNa-Green fluorescence in SC root protoplasts verified a vacuolar localization for Na+ in addition to the presence of a 2- to 6-μm unidentified endosomal compartment containing significantly higher Na+ concentrations.
36
YAMAMOTO, Masashi, Ryoji MATSUMOTO, Naomi OKUDAI e Kensuke ASADA. "Segregation for Rind Texture in Citrus Hybrid Seedlings". Journal of the Japanese Society for Horticultural Science 59, n. 1 (1990): 15–21. http://dx.doi.org/10.2503/jjshs.59.15.
Testo completo
37
Westbrook, Catherine J., David G. Hall, Ed Stover, Yong Ping Duan e Richard F. Lee. "Colonization of Citrus and Citrus-related Germplasm by Diaphorina citri (Hemiptera: Psyllidae)". HortScience 46, n. 7 (luglio 2011): 997–1005. http://dx.doi.org/10.21273/hortsci.46.7.997.
Testo completoAbstract (sommario):
Huanglongbing (HLB) is a serious and devastating disease of citrus caused by Candidatus Liberibacter spp. and vectored by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae). The disease has the potential to greatly limit the production of citrus in Florida and other citrus-growing regions worldwide. Current control of D. citri and HLB is inadequate, but the identification and incorporation of D. citri resistance traits from uncultivated Citrus spp. and Citrus relatives is seen as a potential disease management strategy. In this study, seedlings of 87 Rutaceae seed-source genotypes, primarily in the orange subfamily Aurantioideae, were assessed in the field for their propensity in a free-choice situation for infestations of natural south Florida populations of D. citri. The majority of test populations surveyed hosted all three life stages of D. citri; however, there were significant differences among the test populations in the mean ranks for D. citri eggs (F = 3.13, df = 86, P < 0.0001), nymphs (F = 9.01, df = 86, P < 0.0001), and adults (F = 4.21, df = 86, P < 0.0001). The only sampled test population that was completely avoided by all life stages of D. citri was seedlings of Casimiroa edulis Llave et Lex, commonly known as white sapote, which was one of the few plants included in the study belonging to the Rutaceae subfamily Toddalioideae. Although not completely avoided, very low levels of D. citri were found on two surveyed test populations of Poncirus trifoliata (L.) Raf, seedlings of ‘Simmon's trifoliate’ and ‘Little-Leaf’. Poncirus trifoliata, the trifoliate orange, readily forms hybrids with Citrus spp., is commonly incorporated into rootstock varieties, and has been used in breeding-advanced scion material. The identification of partial resistance in P. trifoliata to D. citri could prove useful in future citrus breeding efforts aimed at reducing the incidence and spread of HLB. Determining if there is true resistance to D. citri in this and other germplasm sources with a low propensity for infestations in free-choice situations will require no-choice experiments.
38
YILDIZ, Ercan, Mustafa KAPLANKIRAN, Turan Hakan DEMİRKESER, Aydin UZUN e Celil TOPLU. "Identification of Zygotic and Nucellar Individuals Produced from Several Citrus Crosses Using SSRs Markers". Notulae Botanicae Horti Agrobotanici Cluj-Napoca 41, n. 2 (6 dicembre 2013): 478. http://dx.doi.org/10.15835/nbha4129037.
Testo completoAbstract (sommario):
Turkey is an important citrus-producing country. However, new cultivars are needed to sustain citrus production and ensure its competitiveness against other crops. There are currently several citrus breeding programs that aim to help overcome the lack of local commercial varieties and to contribute to Turkey’s competitive capacity in the citrus market. In this study, we report the utilization of molecular markers in one such breeding program. Simple sequence repeat (SSR) markers were employed to eliminate nucellar individuals from a hybrid population produced by crossing. The crosses included ‘Fremont’ and ‘Robinson’ mandarins as the female parents and ‘Midknight Valencia’, ‘Rhode Red Valencia’, and ‘Valencia Late’ oranges and ‘Rio Red’ grapefruit cultivars as the male parents. Seedlings with the same banding patterns as the female parent were identified as nucellar seedlings by 11 SSR primers. Primers AG14 and TAA03 were found to be more effective at identifying zygotic individuals than other primers. ‘Fremont’ and ‘Robinson’ mandarins produced 36.91% and 31.09% of nucellar seedlings, respectively. As a pollen parent, ‘Rio Red’ grapefruit had a higher ratio of zygotic seedlings compared to ‘Midknight Valencia’, and can be recommended in breeding programs. Comparative analysis of different citrus fruits in the breeding programs allowed us to design an efficient hybridization scheme for this study.
39
Usman, M., T. Saeed, M. M Khan e B. Fatima. "Occurrence of spontaneous polyploids in Citrus". Horticultural Science 33, No. 3 (23 novembre 2011): 124–29. http://dx.doi.org/10.17221/3751-hortsci.
Testo completoAbstract (sommario):
Seedlings recovered from underdeveloped seeds of different commercial cultivars of Citrus were studied for their ploidy level. Cytological examination revealed that maximum triploid plants were found in lime Kaghzi (15.5%) followed by grapefruit Foster, mandarin Kinnow, sweet orange Musambi and mandarin Feutrell’s Early (7.3%). Lime also produced the highest percentage of tetraploids (9.1%) followed by mandarin Kinnow and grapefruit Foster, while the minimum was found in mandarin Feutrell’s Early. The polyploids were transplanted in pots and after hardening they were grown in the greenhouse for further morphological and genetic assays.
40
Singh, Jagveer, H. S. Dhaliwal, Anirudh Thakur, G. S. Sidhu, P. Chhuneja e Kuldeep Pandey. "Ex vitro recovery of rough lemon (Citrus jambhiri) hybrids and identification with SSR markers". Indian Journal of Agricultural Sciences 90, n. 4 (10 luglio 2020): 823–27. http://dx.doi.org/10.56093/ijas.v90i4.102232.
Testo completoAbstract (sommario):
Rough lemon (Citrus jambhiri Lush) is one of the leading citrus rootstock around the world besides sour orange. In the present studies, rough lemon was crossed with X 639 and Swingle citrumelo at Department of Fruit Science, PAU Ludhiana during 2015-16. Cent per cent seed germination was recorded for both the crosses under in vitro conditions but, the germination rates with growing media in plug trays were significantly lower (91.3 and 89.2% for RL× X and RL × SC, respectively). Higher proportion of multi-foliate seedlings (26.89%) was recovered by in vitro seed culture over the ex vitro seed germination (5.20%). All the multi-foliate seedlings were confirmed by SSR analysis using two primers (F 29 and F 87). The SSR analysis showed that only 85% multifoliate seedlings were zygotic while, the rest were not confirmed to be zygotic. The SSR analysis of the 50 unifoliate F1 seedlings each from both the crosses with 5 SSR primers differentiated seedlings into two groups, viz. zygotic and nucellar seedlings. In RL × X cross, the most efficient SSR marker was F29, which identified 30% F1 unifoliate seedlings to be zygotic followed by CCSME31, which identified 26% unifoliate seedlings as zygotic seedlings while the remaining seedlings were nucellar. In the cross RL × SC, the primer F29 was most efficient as it identified 28% zygotic seedlings and 72% nucellar seedlings whereas, the primer F87 identified 24 and 76% zygotic and nucellar seedlings, respectively.
41
Nemec, S., J. Syversten e Y. Levy. "Water relations of rough lemon (Citrus jambhiri Lush.) citrus seedlings infected withFusarium solani". Plant and Soil 93, n. 2 (giugno 1986): 231–39. http://dx.doi.org/10.1007/bf02374225.
Testo completo
42
Syvertsen, J. P., e J. M. Dunlop. "Hydrophilic Gel Amendments to Sand Soil Can Increase Growth and Nitrogen Uptake Efficiency of Citrus Seedlings". HortScience 39, n. 2 (aprile 2004): 267–71. http://dx.doi.org/10.21273/hortsci.39.2.267.
Testo completoAbstract (sommario):
We tested the hypothesis that amendments of two hydrophilic gels to a sand soil would reduce N leaching losses and increase growth of citrus seedlings. Three-month-old seedlings of `Swingle' citrumelo [Citrus paradisi Macf. × Poncirus trifoliata (L.) Raf.] were transplanted into containers of steam-sterilized Candler sand, amended with a linear acrylamide/acrylate copolymer (PAM), and/or a cross-linked copolymer agronomic gel (AGRO). Two rates of each amendment were applied either alone or together and were either mixed into dry sand prior to seedling transplant, used as a root-dip slurry at transplant or applied to the soil surface in a solution after transplant. Seedlings were grown in the greenhouse for 5 months and irrigated to container capacity with a dilute nutrient solution without leaching. Pots were leached every 2 weeks and total N losses from the soil were measured in the leachate. PAM amendments increased N retention in soil slightly but PAM had no effect on plant growth, water use, N uptake, or N leaching relative to unamended control plants. The AGRO amendments increased seedling growth, plant water use and uptake of N from 11% to 45% above that of the unamended control plants depending on application method. AGRO decreased N concentrations in the leachate to as low as 1 to 6 mg·L-1. Only 6% of the total applied N was leached from the AGRO treatments, which was about half that from the untreated control plants. There was no additional benefit of using both amendments together or of an additional AGRO root dip treatment. The largest plants used the most water, required the most N and had the greatest N uptake efficiency. AGRO amendments clearly enhanced seedling growth, increased their N uptake efficiency, and reduced N losses from this sand soil.
43
Mendes, Beatriz Madalena Januzzi, Raquel Luciana Boscariol, Francisco de Assis Alves Mourão Filho e Weliton Antonio Bastos de Almeida. "Agrobacterium-mediated genetic transformation of 'Hamlin' sweet orange". Pesquisa Agropecuária Brasileira 37, n. 7 (luglio 2002): 955–61. http://dx.doi.org/10.1590/s0100-204x2002000700009.
Testo completoAbstract (sommario):
The development and optimization of efficient transformation protocols is essential in new citrus breeding programs, not only for rootstock, but also for scion improvement. Transgenic 'Hamlin' sweet orange (Citrus sinensis (L.) Osbeck) plants were obtained by Agrobacterium tumefaciens-mediated transformation of epicotyl segments collected from seedlings germinated in vitro. Factors influencing genetic transformation efficiency were evaluated including seedling incubation conditions, time of inoculation with Agrobacterium and co-culture conditions. Epicotyl segments were adequate explants for transformation, regenerating plants by direct organogenesis. Higher percentage of transformation was obtained with explants collected from seedlings germinated in darkness, transferred to 16 hours photoperiod for 2-3 weeks, and inoculated with Agrobacterium for 15-45 min. The best co-culture condition was the incubation of the explants in darkness, for three days in culture medium supplemented with 100 muM of acetosyringone. Genetic transformation was confirmed by performing beta-glucoronidase (GUS) assays and, subsequently, by PCR amplification for the nptII and GUS genes.
44
Chilembwe, Eric H. C., William S. Castle e Daniel J. Cantliffe. "Grading, Hydrating, and Osmotically Priming Seed of Four Citrus Rootstock to Increase Germination Rate and Seedling Uniformity". Journal of the American Society for Horticultural Science 117, n. 3 (maggio 1992): 368–72. http://dx.doi.org/10.21273/jashs.117.3.368.
Testo completoAbstract (sommario):
Commercially processed citrus seeds of Carrizo citrange [Citrus sinensis (L.) Osb. × Poncirus trifoliata (L) Raf.], Swingle citrumelo (C. paradisi Macf. × P. trifoliata), Cleopatra mandarin (C. reticulate Blanco), and sour orange (C. aurantium L.) were used to test the effects of grading, hydrating, and priming on the rate of germination and seedling emergence. Sorting seed into groups by fresh weight or diameter did not generally improve seed performance. Seed fresh weight was highly correlated with maximum seed diameter; also, large seed weight and size were associated with a larger number of embryos. When seedlings from the extra embryos were removed, large seed produced the largest seedlings. Soaking seeds in aerated water significantly increased germination and emergence rates over unsoaked seeds. Soaking at 35C rather than 25C enhanced these differences. Priming seeds in one of three solutions of polyethylene glycol 6000 (—0.6 to—1.2 Mpa) was not successful> as germination and emergence Per centages were lower than in distilled water.
45
MOHAMMED, A. J., e ALI S. A. AL-JANABI. "LIQUEFIED WATER AND ANTIOXIDANTS INFLUENCE ON VEGETATIVE GROWTH AND PHYSIOLOGICAL TRAITS OF SWEET ORANGE". SABRAO Journal of Breeding and Genetics 54, n. 4 (31 ottobre 2022): 917–26. http://dx.doi.org/10.54910/sabrao2022.54.4.22.
Testo completoAbstract (sommario):
Citrus production faces many problems; a major one consists of irrigating citrus seedlings grown at Agricultural Research Stations and various nurseries with saline well water, which determines the growth, reproduction, and spread of citrus in Iraq. The said problem needs addressing to reduce its effects on the growth and reproduction of citrus fruits. Therefore, the latest research aimed to determine the effects of regular liquefied water and saline well water, in addition to a foliar spray of aspartic and ascorbic acids, on the growth and physiological properties of the grafted orange seedlings. The local citrus seedlings of the same age and size were selected and used as the original and grafted with local orange buds. They were shifted and tested for the above three factors at the Horticulture and Forestry Division, Najaf Agriculture Directorate, Iraq. The findings showed that irrigation with regular liquefied water had improved the growth traits, i.e., plant height, leaves plant-1, leaf area plant-1, and dry biomass weight of sweet orange seedlings, compared with saline well water. Results further revealed that foliar application of aspartic acid (100 mg L-1) positively affected the leaves plant-1 and dry biomass weight compared with the control. The ascorbic acid (4000 mg L-1) application gave highly superior and well-responsive reactions for most of the traits, i.e., leaves plant-1 (69.3 leaves plant-1), leaf area plant-1 (3888 cm2), dry biomass weight (0.3629 g), and total chlorophyll content (7.03 mg 100 g-1 fresh weight) in orange seedlings.
46
Wu, Qiang Sheng, e Qiu Dan Ni. "Selection of an Efficient Growth Container for Mycorrhization of Trifoliate Orange Seedlings in Nursery". Advanced Materials Research 726-731 (agosto 2013): 4517–20. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.4517.
Testo completoAbstract (sommario):
Citrus plants strongly depend on arbuscular mycorrhizas (AMs) but low AM colonization found in the field. Therefore, mycorrhization of seedlings is vital for better citrus growth vigor. The study evaluated the effects of four containers (earthen pot, plastic pot, nursery cylinder, and nursery bag) on growth, mycorrhizal development, root system architecture (RSA) and chlorophyll concentration of trifoliate orange (Poncirus trifoliata) seedlings inoculated withGlomus versiforme. After five months, AM seedlings grown in an earthen pot displayed the best AM colonization, vesicles, entry points, shoot dry weight, total plant dry weight, plant height, stem diameter, leaf number, RSA traits (taproot length, total length, projected area, surface area, volume, and number of first lateral root), and chlorophyllaand total chlorophyll concentrations, the AM seedlings grown in nursery cylinder and nursery bag better, and the seedlings grown in plastic pot worst. It suggests that mouth diameter of containers is key to mycorrhization of seedlings. Meanwhile, earthen pot is the best container for mycorrhization of trifoliate orange seedlings.
47
Ferguson, J. J., e J. A. Menge. "Response of Citrus Seedlings to Various Field Inoculation Methods with Glomus deserticola in Fumigated Nursery Soils". Journal of the American Society for Horticultural Science 111, n. 2 (marzo 1986): 288–92. http://dx.doi.org/10.21273/jashs.111.2.288.
Testo completoAbstract (sommario):
Abstract Broadcasting, banding, and drilling were more effective in the field inoculation of plants with the vesicular arbuscular mycorrhizal fungus, Glomus deserticola Trappe, Bloss and Menge than seed inoculation or the application of lyophilized roots to both direct-seeded and transplanted citrus seedlings. Mechanized field inoculation of direct seeded and transplanted citrus seedlings is feasible, using fertilizer banding equipment, and seeding machines. In oculum remained consistently infective after soil inoculation for up to 2.5 months in fumigated field soil and for up to 1.5 months in mycorrhizal pot cultures of citrus grown in the greenhouse.
48
Beloti, Vitor H., Gustavo R. Alves, Helvécio D. Coletta-Filho e Pedro T. Yamamoto. "The Asian Citrus Psyllid Host Murraya koenigii Is Immune to Citrus Huanglongbing Pathogen ‘Candidatus Liberibacter asiaticus’". Phytopathology® 108, n. 9 (settembre 2018): 1089–94. http://dx.doi.org/10.1094/phyto-01-18-0012-r.
Testo completoAbstract (sommario):
The Asian citrus psyllid (ACP) Diaphorina citri, vector of ‘Candidatus Liberibacter asiaticus’ (CLas), the putative causal agent of citrus Huanglongbing (HLB), is controlled by application of insecticides, which, although effective, has resulted in serious biological imbalances. New management tools are needed, and the technique known as “trap crop” has been attracting attention. A potential plant for use as a trap crop in the management of the ACP is Murraya koenigii (curry leaf). However, for this plant to be used in the field, it needs to be attractive for the vector and must not harbor CLas. To verify the potential of curry leaf as trap crop for the management of HLB, we investigated the ability of D. citri to transmit CLas to M. koenigii, and to other test plants, including M. paniculata (orange jasmine) and cultivar Valencia sweet-orange seedlings. For the tests, the insects were reared on a symptomatic CLas-infected plant and allowed to feed on the three test plant species. The overall maximum transmission rate for the citrus seedlings was 83.3%, and for orange jasmine was 33.3%. Successful transmission of CLas by ACP to the curry-leaf seedlings was not observed, and it was treated as immune to CLas. Supported by the previous results that M. koenigii is attractive for ACP, these results indicate that curry leaf is an excellent candidate for use as a trap crop, to improve the management of the insect vector and consequently of HLB.
49
Yin, Hang, Junxiu Wang, Yao Zeng, Xinjian Shen, Yizhong He, Lili Ling, Li Cao, Xingzheng Fu, Liangzhi Peng e Changpin Chun. "Effect of the Rare Earth Element Lanthanum (La) on the Growth and Development of Citrus Rootstock Seedlings". Plants 10, n. 7 (6 luglio 2021): 1388. http://dx.doi.org/10.3390/plants10071388.
Testo completoAbstract (sommario):
Rare earth elements (REEs) can affect the growth and development of plants. However, few studies have been carried out on the effects of REEs on citrus seedlings. In this study, the growth parameters, toxicity symptoms, chlorophyll content, and La content of three citrus rootstocks are analyzed under different concentrations of La, a representative REE. The results show that the growth of citrus rootstock seedlings was stimulated at La ≤ 0.5 mmol·L−1 and inhibited at concentrations above 1 mmol·L−1. The chlorophyll and carotenoid contents of trifoliate orange (Poncirus trifoliata L. Raf.) and Ziyang Xiangcheng (C. junos Sieb. ex Tanaka) leaves of plants grown at low concentrations of La (≤1.5 mmol·L−1) were similar to those of the control but were significantly reduced at 4 mmol·L−1 La. Toxic symptoms gradually appeared with increasing La concentrations, with yellowed leaves and burst veins appearing at 4 mmol·L−1 La. The symptoms of toxicity were most severe in trifoliate orange, followed by Shatian Pomelo (Citrus grandis var. shatinyu Hort) and then Ziyang Xiangcheng. Moreover, in leaves, the Ca content was significantly negatively correlated with La content (p < 0.01). These results indicate that La has a hormesis effect on the growth of citrus rootstocks. Of the studied citrus seedlings, Ziyang Xiangcheng is the most resistant to La.
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Huang, Wei-Tao, Yi-Zhi Xie, Xu-Feng Chen, Jiang Zhang, Huan-Huan Chen, Xin Ye, Jiuxin Guo, Lin-Tong Yang e Li-Song Chen. "Growth, Mineral Nutrients, Photosynthesis and Related Physiological Parameters of Citrus in Response to Nitrogen Deficiency". Agronomy 11, n. 9 (16 settembre 2021): 1859. http://dx.doi.org/10.3390/agronomy11091859.
Testo completoAbstract (sommario):
Limited data are available on the physiological responses of Citrus to nitrogen (N) deficiency. ‘Xuegan’ (Citrus sinensis (L.) Osbeck) and ‘Shantian pummelo’ (Citrus grandis (L.) Osbeck) seedlings were fertilized with nutrient solution at a N concentration of 0, 5, 10, 15 or 20 mM for 10 weeks. N deficiency decreased N uptake and N concentration in leaves, stems and roots and disturbed nutrient balance and homeostasis in plants, thus inhibiting plant growth, as well as reducing photosynthetic pigment levels and impairing thylakoid structure and photosynthetic electron transport chain (PETC) in leaves, hence lowering CO2 assimilation. The imbalance of nutrients intensified N deficiency’s adverse impacts on biomass, PETC, CO2 assimilation and biosynthesis of photosynthetic pigments. Citrus displayed adaptive responses to N deficiency, including (a) elevating the distributions of N and other elements in roots, as well as root dry weight (DW)/shoot DW ratio and root-surface-per-unit volume and (b) improving photosynthetic N use efficiency (PNUE). In general, N deficiency had less impact on biomass and photosynthetic pigment levels in C. grandis than in C. sinensis seedlings, demonstrating that the tolerance of C. grandis seedlings to N deficiency was slightly higher than that of C. sinensis seedlings, which might be related to the higher PNUE of the former.