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Journal articles on the topic 'Stem photosynthesi'
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1
Zagorchev, Lyuben, Alexandra Atanasova, Ivanela Albanova, Anelia Traianova, Petko Mladenov, Margarita Kouzmanova, Vasilij Goltsev, Hazem M. Kalaji, and Denitsa Teofanova. "Functional Characterization of the Photosynthetic Machinery in Smicronix Galls on the Parasitic Plant Cuscuta campestris by JIP-Test." Cells 10, no. 6 (June 5, 2021): 1399. http://dx.doi.org/10.3390/cells10061399.
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Members of the genus Cuscuta are generally considered to be non-photosynthetic, stem-holoparasitic flowering plants. Under certain circumstances, at least some members of the genus are capable of limited photosynthesis. The galls of the Smicronyx weevils formed on Cuscuta campestris are particularly rich in chlorophylls compared to the stem of the parasitic plant. In the present study, we aimed to characterize the photosynthetic activity in the inner and outer gall cortices in comparison to the non-photosynthetic stems and a reference plant (Arabidopsis thaliana). The recorded prompt chlorophyll fluorescence transients were analyzed using JIP test. Detailed analysis of the chlorophyll fluorescence confirmed the presence of actively functioning photosynthetic machinery, especially in the inner cortex of the galls. This photosynthesis, induced by the insect larvae, did not reach the levels of the photosynthetic activity in Arabidopsis thaliana plants. Thylakoid protein complexes were identified by separation with two-dimensional Blue Native/SDS PAGE. It appeared that some of the complexes presented in A. thaliana are missing in C. campestris. We hypothesize that the insect-triggered transition from non-photosynthetic to photosynthetic tissue in the gall is driven by the increased requirements for nutrients related to the larval nutrition.
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Alessio, Giorgio A., Fabrizio Pietrini, Federico Brilli, and Francesco Loreto. "Characteristics of CO2 exchange between peach stems and the atmosphere." Functional Plant Biology 32, no. 9 (2005): 787. http://dx.doi.org/10.1071/fp05070.
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Gas exchange by stems is dominated by respiratory CO2 emission, but photosynthetic CO2 uptake might also occur in stem bark. We show that light-dependent CO2 uptake was present and often exceeded CO2 release by respiration in illuminated current-year peach (Prunus persica L.) stems. Respiration of peach stems, as detected by 12CO2 release into air in which the natural concentration of 12CO2 was replaced with 13CO2, was lower in the light than in the dark, but this accounted for only a fraction of the observed total CO2 uptake by illuminated stems. Stem photosynthesis was saturated at low light and was negatively affected by elevated assay temperatures (30°C), especially when combined with light intensities above saturation. An inefficient mechanism of heat dissipation by transpiration in stomata-free stems might help explain this effect. Photosynthesis was rapidly stimulated and the electron transport rate was reduced when photorespiration was suppressed by exposure to low (2 kPa) oxygen. The time-course of these changes was closely associated with a transient burst of CO2 uptake concurrent with a reduced inhibition of fluorescence yield. Photosynthesis was also stimulated by exposure to elevated (twice ambient) CO2 concentration. These combined measurements of gas exchange and fluorescence suggested that (a) photorespiration may also be active in the bark of peach stems, (b) O2 and CO2 concentrations in the bark of peach stems may be similar to ambient concentrations, (c) a large amount of electron transport unrelated to photosynthesis and photorespiration may also be present in peach stems, and (d) stem photosynthesis may be enhanced under future atmospheric conditions.
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Míguez, Fátima, Beatriz Fernández-Marín, Antonio Hernández, José Maria Becerril, and José Ignacio García-Plazaola. "Does age matter under winter photoinhibitory conditions? A case study in stems and leaves of European mistletoe (Viscum album)." Functional Plant Biology 42, no. 2 (2015): 175. http://dx.doi.org/10.1071/fp14083.
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European mistletoe (Viscum album L.) is a hemiparasitic plant with perennial leaves and photosynthetic stems easily discernible according to their age. These properties make V. album the perfect species to (i) compare the mechanisms of seasonal acclimation of photosynthetic stems with those of leaves, and (ii) evaluate the influence of ageing in the efficiency of photosynthetic tissues. To achieve these general objectives, photosynthetic pigments, maximal photochemical efficiency of PSII (Fv/Fm), recovery kinetics and key thylakoidal proteins were analysed during winter and spring in leaves and at different age stems. During winter, some woody species are able to maintain photosynthetic activity, but at lower rates than during spring. In the case of V. album, photosynthetic relevance of green stems appears equal to leaves in terms of total area. Besides, mistletoe stems are able to maintain higher Fv/Fm and lower level of antioxidants than leaves, especially during winter season. The recovery from winter photoinhibition is also faster in stems than in leaves. Thylakoidal protein composition (mainly high levels of D1) also supports the idea of stems as main photosynthetic organs in V. album during winter. Further, in winter, the level of photoinhibition of V. album stems decreased concomitantly with ageing. This work highlights the importance of stem photosynthesis in plant carbon balance and demonstrates that ageing does not necessarily imply a loss of vitality in stems.
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Rey-Sanchez, Camilo, and Juan M. Posada. "Effect of temporally heterogeneous light on photosynthetic light use efficiency, plant acclimation and growth in Abatia parviflora." Functional Plant Biology 46, no. 7 (2019): 684. http://dx.doi.org/10.1071/fp18279.
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Individual leaves have a unique instantaneous photosynthetic photon flux density (PPFD) at which net photosynthetic light use efficiency (ϵL, the ratio between net photosynthesis and PPFD) is maximised (PPFDϵmax). When PPFD is above or below PPFDϵmax, efficiency declines. Thus, we hypothesised that heterogeneous PPFD conditions should increase the amount of time leaves photosynthesise at a PPFD different than PPFDϵmax and result in reduced growth. To date, this prediction has not been rigorously tested. Here, we exposed seedlings of Abatia parviflora Ruiz & Pav to light regimes of equal total daily irradiance but with three different daily time courses of PPFD: constant PPFD (No_H), low heterogeneity (Low_H) and high heterogeneity (High_H). Mean ϵL, leaf daily photosynthesis and plant growth were all significantly higher in No_H and Low_H plants than in High_H plants, supporting our hypothesis. In addition, mean ϵL was positively related to final plant biomass. Unexpectedly, High_H plants had more etiolated stems and more horizontal leaves than No_H and Low_H plants, possibly due to exposure to low PPFD in the morning and afternoon. In conclusion, PPFD heterogeneity had an important effect on average ϵL, photosynthesis and growth, but also on allocation and plant morphology.
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Armitage, A. M., N. G. Seager, I. J. Warrington, and D. H. Greer. "LIGHT, TEMPERATURE AND PHOTOPERIOD AFFECT THE USEFULNESS OF OXYPETALUM CAERULEUM, TWEEDIA, AS A CUT FLOWER CROP." HortScience 25, no. 9 (September 1990): 1160d—1160. http://dx.doi.org/10.21273/hortsci.25.9.1160d.
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A progressive increase in temperature from 14 to 30C resulted in linear increases in stem length and node number and decreases in stem diameter and stem strength. Higher temperatures also resulted in additional flower abortion, reduced time to flowering and fewer flowering stems per inflorescence. Reduction in the photosynthetic photon flux (PPF) from 695 to 315 μmole m-2s-1 had similar effects as increasing the temperature on vegetative parameters but had little effect on reproductive parameters. The rate of stem elongation was greatest at low PPF for all temperatures and at high temperature for all PPF treatments. Net photosynthesis rose between 14 and 22C and declined at 30C for all PPF treatments. Long photoperiods (12, 14 hr.) resulted in longer internodes, longer stems and more flowers per cyme than short photoperiods (8, 10 hr) but photoperiod had little effect on flowering time.
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Wittmann, Christiane, and Hardy Pfanz. "Bark and woody tissue photosynthesis: a means to avoid hypoxia or anoxia in developing stem tissues." Functional Plant Biology 41, no. 9 (2014): 940. http://dx.doi.org/10.1071/fp14046.
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In woody plants, oxygen transport and delivery via the xylem sap are well described, but the contribution of bark and woody tissue photosynthesis to oxygen delivery in stems is poorly understood. Here, we combined stem chlorophyll fluorescence measurements with microsensor quantifications of bark O2 levels and oxygen gas exchange measurements of isolated current-year stem tissues of beech (Fagus sylvatica L.) and pedunculate oak (Quercus robur L.) to investigate how bark and woody tissue photosynthesis impairs the oxygen status of stems. Measurements were made before bud break, when the axial path of oxygen supply via the xylem sap is impeded. At that time, bark O2 levels showed O2 concentrations below the atmospheric concentration, indicating hypoxic conditions or O2 deficiency within the inner bark, but the values were always far away from anoxic. Under illumination bark and woody tissue photosynthesis rapidly increased internal oxygen concentrations compared with plants in the dark, and thereby counteracted against localised hypoxia. The highest photosynthetic activity and oxygen release rates were found in the outermost cortex tissues. By contrast, rates of woody tissue photosynthesis were considerably lower, due to the high light attenuation of the bark and cortex tissues, as well as resistances in radial oxygen diffusion. Therefore, our results confirm that bark and woody tissue photosynthesis not only play a role in plant carbon economy, but may also be important for preventing low oxygen-limitations of respiration in these dense and metabolically active tissues.
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Kumar, Sunjeet, Xinfang Huang, Gaojie Li, Qun Ji, Kai Zhou, Guopeng Zhu, Weidong Ke, Hongwei Hou, Honglian Zhu, and Jingjing Yang. "Comparative Transcriptomic Analysis Provides Novel Insights into the Blanched Stem of Oenanthe javanica." Plants 10, no. 11 (November 17, 2021): 2484. http://dx.doi.org/10.3390/plants10112484.
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In the agricultural field, blanching is a technique used to obtain tender, sweet, and delicious water dropwort stems by blocking sunlight. The physiological and nutritional parameters of blanched water dropwort have been previously investigated. However, the molecular mechanism of blanching remains unclear. In the present study, we investigated transcriptomic variations for different blanching periods in the stem of water dropwort (pre, mid, post-blanching, and control). The results showed that many genes in pathways, such as photosynthesis, carbon fixation, and phytohormone signal transduction as well as transcription factors (TFs) were significantly dysregulated. Blanched stems of water dropwort showed the higher number of downregulated genes in pathways, such as photosynthesis, antenna protein, carbon fixation in photosynthetic organisms, and porphyrin and chlorophyll metabolism, which ultimately affect the photosynthesis in water dropwort. The genes of hormone signal transduction pathways (ethylene, jasmonic acid, brassinosteroid, and indole-3-acetic acid) showed upregulation in the post-blanched water dropwort plants. Overall, a higher number of genes coding for TFs, such as ERF, BHLH, MYB, zinc-finger, bZIP, and WRKY were overexpressed in blanched samples in comparison with the control. These genes and pathways participate in inducing the length, developmental processes, pale color, and stress tolerance of the blanched stem. Overall, the genes responsive to blanching, which were identified in this study, provide an effective foundation for further studies on the molecular mechanisms of blanching and photosynthesis regulations in water dropwort and other species.
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Hill, Judson P., and Matthew J. Germino. "Coordinated variation in ecophysiological properties among life stages and tissue types in an invasive perennial forb of semiarid shrub steppe." Canadian Journal of Botany 83, no. 11 (November 2005): 1488–95. http://dx.doi.org/10.1139/b05-116.
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Semiarid lands of North America are vulnerable to invasion by exotic forbs that frequently have an extended phenology compared with native herbaceous species. We hypothesized that photosynthetic stems, rosette leaves, and cauline leaves of Centaurea maculosa Lam. (knapweed) would differ in ecophysiological specialization and that these differences would enhance plant carbon uptake across seasonal variations in microclimate. Photosynthesis, water relations, and morphological features of C. maculosa were measured under natural variations in temperature and soil water, and under manipulated light environments, in adults compared with seedlings having only rosette leaves. Carbon gain was greater in adults than in seedlings owing to high photosynthesis in cauline and rosette leaves when water was abundant. Otherwise, photosynthesis was relatively lower but persistent through drought in all tissues and ages until senescence. Photosynthesis decreased with water stress in all tissues except stems. Stems comprised up to 36% of photosynthetic area following senescence of rosette leaves during seasonal drought. Seedlings expressed shade acclimation compared with rosette and especially cauline leaves of adults, although adult rosette leaves had flexible photosynthetic light responses. Contrasting ecophysiological specializations of photosynthetic tissues enhance carbon gain of adult C. maculosa as light, water, and temperature vary during its relatively long growth season.
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Guralnick, Lonnie J., Gerald Edwards, Maurice S. B. Ku, Brandon Hockema, and Vince Franceschi. "Photosynthetic and anatomical characteristics in the C4crassulacean acid metabolism-cycling plant Portulaca grandiflora." Functional Plant Biology 29, no. 6 (2002): 763. http://dx.doi.org/10.1071/pp01176.
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This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. Portulaca grandiflora (Lind.) is a succulent species with C4 photosynthesis and crassulacean acid metabolism (CAM) cycling in leaves, and CAM-idling type photosynthesis in stems. We investigated the level and localization of carbon fixation enzymes and photosynthetic activity of leaves and stems of P. grandiflora under well-watered and drought conditions. As CAM activity increased during water stress, the leaf water-storage tissue collapsed, presumably transferring water to the bundle sheath and mesophyll cells, and so maintaining the C4 photosynthetic pathway. Tissue prints indicated an increase in phosphoenolpyruvate carboxylase (PEPC) in the water-storage tissue of leaves and the cortex of stems. Immunoblot analyses after 10 d of water stress showed that leaves had a slight decrease in the proteins of the C4-CAM pathway, while at the same time a new isoform of NADP-malic enzyme (NADP-ME) appeared. In contrast, the stem showed increases in proteins of the CAM pathway when water stressed. Under water stress, diurnal fluctuation in acidity in leaves was not accompanied by a net gain or loss of CO2 at night, and there was sustained, but decreased, fixation of CO2 during the day, characteristic of CAM cycling. High gross rates of O2 evolution were maintained during the day under water stress, suggesting induction of alternative electron sinks. With induced diurnal fluctuations in acidity in stems, there was no net carbon gain during the day or night. These results demonstrate, for the first time, that the stem of P. grandiflora is an inducible CAM-idling tissue. Our results also indicate that the C4 and CAM pathways operate independently of one another in P. grandiflora.
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Voznesenskaya, Elena V., Nuria K. Koteyeva, Asaph Cousins, and Gerald E. Edwards. "Diversity in structure and forms of carbon assimilation in photosynthetic organs in Cleome (Cleomaceae)." Functional Plant Biology 45, no. 10 (2018): 983. http://dx.doi.org/10.1071/fp17323.
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Photosynthesis in different organs of Cleome was analysed in four species known to have differences in leaf photosynthesis: Cleome africana Botsch. (C3), Cleome paradoxa R.Br. (C3-C4 intermediate), Cleome angustifolia Forssk. and Cleome gynandra L. (C4). The chlorophyll content, carbon isotope composition, stomatal densities, anatomy, levels and compartmentation of some key photosynthetic enzymes, and the form and function of photosynthesis were determined in different organs of these species. In the three xerophytes, C. africana, C. paradoxa, and C. angustifolia, multiple organs contribute to photosynthesis (cotyledons, leaves, petioles, stems and pods) which is considered important for their survival under arid conditions. In C. africana, all photosynthetic organs have C3 photosynthesis. In C. paradoxa, cotyledons, leaves, stems and petioles have C3-C4 type features. In C. angustifolia, the pods have C3 photosynthesis, whereas all other organs have C4 photosynthesis with Kranz anatomy formed by a continuous, dual layer of chlorenchyma cells. In the subtropical C4 species C. gynandra, cotyledons, leaves, and pods develop C4 photosynthesis, with Kranz anatomy around individual veins; but not in stems and petioles which have limited function of photosynthesis. The diversity in forms and the capacity of photosynthesis in organs of these species to contribute to their carbon economy is discussed.
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Armitage, A. M., N. G. Seager, I. J. Warrington, D. H. Greer, and J. Reyngoud. "Response of Oxypetalum caeruleum to Irradiance, Temperature, and Photoperiod." Journal of the American Society for Horticultural Science 115, no. 6 (November 1990): 910–14. http://dx.doi.org/10.21273/jashs.115.6.910.
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Incremental increases in temperature from 14 to 22 to 30C resulted in linear increases in stem length and node number and decreases in stem diameter and stem strength of Oxypetalum caeruleum (D. Don.) Decne. Higher temperatures also resulted in additional flower abortion, reduced time to flowering, and fewer flowering stems per inflorescence. Reduction in the photosynthetic photon flux (PPF) from 695 to 315 μmol·s-1·m-2 had similar effects as increasing the temperature on vegetative characteristics, but had little effect on reproductive ones. The rate of stem elongation was greatest at low PPF for all temperatures and at high temperature for all PPF treatments. Net photosynthesis rose between 14 and 22C and declined at 30C for all PPF treatments. Long photoperiods (12 or 14 hours) resulted in longer internodes, longer stems, and more flowers per cyme than short photoperiods (8 or 10 hours), but photoperiod had little effect on flowering time. Treatments to reduce latex coagulant and silver thiosulfate treatments had no significant effect on vase life.
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Knoll, Mathilde, and Helmut Redl. "Gas exchange of field-grown Vitis vinifera L. cv. zweigelt leaves in relation to leaf age and position along the stem." OENO One 46, no. 4 (December 31, 2012): 281. http://dx.doi.org/10.20870/oeno-one.2012.46.4.1524.
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<p style="text-align: justify;"><strong>Aims</strong>: The study aimed to investigate the effects of leaf age and position along the stem on the seasonal evolution of photosynthesis and water use efficiency (WUE) of primary leaves of field-grown grapevines (<em>Vitis</em> <em>vinifera </em>L. cv. Zweigelt) under natural growing conditions in the Pannonian climate.</p><p style="text-align: justify;"><strong>Methods and results</strong>: Single-leaf gas exchange measurements were carried out in three vineyards with different planting densities, training systems and canopy management in the Neusiedlersee region (Burgenland, Austria). From the beginning of leaf development until flowering, basal leaves in the fruiting zone showed the highest photosynthetic activity. After flowering until ripening, the zone with the highest photosynthetic activity continuously moved in the apical direction. Leaves reached their maximum photosynthetic activity 30 to 40 days after emergence, depending on investigation site and vineyard management. Due to sufficient water supply, photosynthesis of old leaves decreased slowly; thus 100 days after unfolding leaves still retained 65% to 75% of their maximum photosynthetic activity.</p><p style="text-align: justify;"><strong>Conclusion</strong>: The development of single-leaf photosynthesis in the Zweigelt grapevine corresponded to the results of prior investigations on other grape varieties. However, vineyard management strongly influenced the evolution of gas exchange during the growing period. Leaves from vines stressed by high crop load or poor canopy management showed early leaf senescence and a strong decline in photosynthetic activity after reaching maximum level. Well-watered leaves from shoot-thinned vines with moderate crop load and equal light exposure throughout the canopy exhibited high photosynthesis with a much slower decrease in older leaves.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: The results indicate that under favourable growing conditions ensured by adequate water supply and canopy management, basal leaves maintain good photosynthesis and WUE over a long period of time. Thus old leaves, as well, can contribute to the photosynthesis of the entire vine.</p>
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Moore, Georgianne W., David A. Watts, and John A. Goolsby. "Ecophysiological Responses of Giant Reed (Arundo donax) to Herbivory." Invasive Plant Science and Management 3, no. 4 (December 2010): 521–29. http://dx.doi.org/10.1614/ipsm-d-10-00007.1.
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AbstractThe effect of invasive species might be lessened if herbivores reduced transpiration and growth rates; however, simply removing photosynthetic material might not ensure that the transpiration rate of active leaf tissue decreases. We assessed whether biological control has an injurious effect on the target plant species, giant reed (Arundo donax), by quantifying leaf photosynthetic and transpiration responses to two herbivores: an armored scale, Rhizaspidiotus donacis, and a stem-galling wasp, Tetramesa romana. Herbivory by a sap-feeding scale and a stem-galling wasp both separately and together, reduces the rates of leaf level physiological processes in A. donax. The effect of the wasp increases with density and reduces photosynthesis by reducing the carboxylation rate of ribulose-1,5-bisphosphate carboxylase oxygenase, which controls CO2 fixation in photosynthesis. The scale insect reduces photosynthesis by decreasing the maximum rate of electron transport, which determines how much light energy can be captured in photosynthesis. The effect of the armored scale takes approximately 5 mo after infestation, which coincides with generation time. When both insects are present at the same time, the effect of their herbivory appears additive after time for the scale to reproduce. We conclude that a combination of two herbivores can have a stronger physiological effect than one type of herbivore, likely because of their different effects on leaf function.
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Claypool, Nicholas B., and J. Heinrich Lieth. "Green Light Improves Photosystem Stoichiometry in Cucumber Seedlings (Cucumis sativus) Compared to Monochromatic Red Light." Plants 10, no. 5 (April 21, 2021): 824. http://dx.doi.org/10.3390/plants10050824.
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It has been shown that monochromatic red and blue light influence photosynthesis and morphology in cucumber. It is less clear how green light impacts photosynthetic performance or morphology, either alone or in concert with other wavelengths. In this study, cucumber (Cucumis sativus) was grown under monochromatic blue, green, and red light, dichromatic blue–green, red–blue, and red–green light, as well as light containing red, green, and blue wavelengths, with or without supplemental far-red light. Photosynthetic data collected under treatment spectra at light-limiting conditions showed that both red and green light enhance photosynthesis. However, photosynthetic data collected with a 90% red, 10% blue, 1000 µmol photons m−2 s−1, saturating light show significantly lower photosynthesis in the green, red, and red–green treatments, indicating a blue light enhancement due to photosystem stoichiometric differences. The red–green and green light treatments show improved photosynthetic capacity relative to red light, indicating partial remediation by green light. Despite a lower quantum efficiency and the lowest ambient photosynthesis levels, the monochromatic blue treatment produced among the tallest, most massive plants with the greatest leaf area and thickest stems.
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Cui, Xin, Huifang Cen, Cong Guan, Danyang Tian, Huayue Liu, and Yunwei Zhang. "Photosynthesis capacity diversified by leaf structural and physiological regulation between upland and lowland switchgrass in different growth stages." Functional Plant Biology 47, no. 1 (2020): 38. http://dx.doi.org/10.1071/fp19086.
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Understanding and enhancing switchgrass (Panicum virgatum L.) photosynthesis will help to improve yield and quality for bio-industrial applications on cellulosic biofuel production. In the present study, leaf anatomical traits and physiological characteristics related to photosynthetic capacity of both lowland and upland switchgrass were recorded from four varieties across the vegetative, elongation and reproductive growth stages. Compared with the upland varieties, the lowland switchgrass showed 37–59, 22–64 and 27–73% higher performance on height, stem and leaf over all three growth stages. Leaf anatomical traits indicated that the leaves of lowland varieties provided more space for carbon assimilation and transportation caused by enhanced cell proliferation with more bundles sheath cells and larger contact areas between the bundle sheath and mesophyll cells (CAMB), which lead to the 32–72% higher photosynthetic capacity found in the lowland varieties during vegetative and elongation growth. However, photosynthetic capacity became 22–51% higher in the upland varieties during the reproductive stage, which is attributed to more photosynthetic pigment. In conclusion, lowland varieties gain a photosynthetic advantage with enhanced bundle sheath cell proliferation, while the upland varieties preserved more photosynthetic pigments. Our study provides new insights for improving the yield in crops by enhancing photosynthesis with anatomical and physiological strategies.
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Damascos, Maria Angélica, Carlos Cesar Ronquim, and Carlos Henrique Britto Assis Prado. "Gas exchange and plant growth after defoliation on Leandra lacunosa, a cerrado woody species with continuous leaf production." Brazilian Archives of Biology and Technology 48, no. 6 (November 2005): 967–74. http://dx.doi.org/10.1590/s1516-89132005000800013.
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Morphological and physiological leaf traits were studied on control and defoliated potted Leandra lacunosa young plants. After defoliation, remaining bottom leaves showed no significant change in net photosynthesis and stomatal conductance values with time, but the leaf transpiration rate was higher. The production of the new leaves was greater after defoliation in top defoliated plants. Bottom defoliated plants increased stem extension rates and net photosynthesis transitorily. Two months after defoliation, control and defoliated plants did not differ in stem length and root dry mass values. In spite of smaller area and photosynthetic capacity, remaining bottom leaves were able to compensate top leaves elimination. The effectiveness of this compensatory response, however, depended on the ability of new leaves to escape from herbivores.
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Barthou, H., and R. Buis. "Morphogenèse foliaire et activité photosynthétique chez le soja (Glycine max)." Canadian Journal of Botany 66, no. 6 (June 1, 1988): 1039–46. http://dx.doi.org/10.1139/b88-149.
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The main stem development and the photosynthetic activity of leaves 2 to 9 were studied in soja (Glycine max (L.) Merr.) at the leaf blade extension and adult stages. A correlation between the different leaf growth parameters (rates, durations) and the phyllochrone has been demonstrated. That correlation varied with the age and rank of the leaf. Moreover, the existence of correlations between net photosynthesis on one hand and the rate of development and the leaf growth kinetics on the other hand reveals an interdependence between photosynthesis and morphogenesis. [Journal translation]
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Ladeynova, Maria, Maxim Mudrilov, Ekaterina Berezina, Dmitry Kior, Marina Grinberg, Anna Brilkina, Vladimir Sukhov, and Vladimir Vodeneev. "Spatial and Temporal Dynamics of Electrical and Photosynthetic Activity and the Content of Phytohormones Induced by Local Stimulation of Pea Plants." Plants 9, no. 10 (October 15, 2020): 1364. http://dx.doi.org/10.3390/plants9101364.
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A local leaf burning causes variation potential (VP) propagation, a decrease in photosynthesis activity, and changes in the content of phytohormones in unstimulated leaves in pea plants. The VP-induced photosynthesis response develops in two phases: fast inactivation and long-term inactivation. Along with a decrease in photosynthetic activity, there is a transpiration suppression in unstimulated pea leaves, which corresponds to the long-term phase of photosynthesis response. Phytohormone level analysis showed an increase in the concentration of jasmonic acid (JA) preceding a transpiration suppression and a long-term phase of the photosynthesis response. Analysis of the spatial and temporal dynamics of electrical signals, phytohormone levels, photosynthesis, and transpiration activity showed the most pronounced changes in the more distant leaf from the area of local stimulation. The established features are related to the architecture of the vascular bundles in the pea stem.
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Tomasella, Martina, Sara Natale, Francesco Petruzzellis, Sara Di Bert, Lorenzo D’Amico, Giuliana Tromba, and Andrea Nardini. "No Evidence for Light-Induced Embolism Repair in Cut Stems of Drought-Resistant Mediterranean Species under Soaking." Plants 11, no. 3 (January 24, 2022): 307. http://dx.doi.org/10.3390/plants11030307.
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(1) Recent studies suggested that stem photosynthesis could favor bark water uptake and embolism recovery when stem segments are soaked in water under light conditions, but evidence for this phenomenon in drought-resistant Mediterranean species with photosynthetic stems is missing. (2) Embolism recovery upon immersion in water for 2 h–4 h under light was assessed (i) via a classical hydraulic method in leafless Fraxinus ornus and Olea europaea branch segments stressed to xylem water potentials (Yxyl) inducing ca. 50% loss of hydraulic conductivity (PLC) and (ii) via X-ray micro-CT imaging of the stem segments of drought-stressed potted F. ornus saplings. Hydraulic recovery was also assessed in vivo in intact drought-stressed F. ornus saplings upon soil re-irrigation. (3) Intact F. ornus plants recovered hydraulic function through root water uptake. Conversely, the soaked stem segments of both species did not refill embolized conduits, although Yxyl recovered to pre-stress levels (between −0.5 MPa and −0.2 MPa). (4) We hypothesize that xylem embolism recovery through bark water uptake, even in light conditions, may not be a common phenomenon in woody plants and/or that wounds caused by cutting short stem segments might inhibit the refilling process upon soaking.
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Gou, Qianqian, Lulu Xi, Yuda Li, and Guohua Wang. "The Responses of Four Typical Annual Desert Species to Drought and Mixed Growth." Forests 13, no. 12 (December 13, 2022): 2140. http://dx.doi.org/10.3390/f13122140.
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Soil desiccation is increasingly threatening the growth of vegetation in artificial forests at the margins of arid desert oases, where a variety of annual herbaceous plants coexist. It is important to understand the response of annual desert plants to droughts and mixed growth and the resulting patterns of change in photosynthetic and physiological properties. Our results showed that annual plants were primarily affected by drought stress, and the effect of interspecific competition was significant only under severe drought stress. In the sprouting stage, moderate drought increased seed germination rates, whereas severe drought stress decreased the germination rates. In the growth phase, the aboveground and belowground parts of annual herbaceous plants showed a synergistic response to drought. Under mild and moderate drought stress, annual herbaceous plants promoted photosynthesis by increasing chlorophyll content, thereby promoting plant stem growth. Following moderate and high drought, root vigor increased to maintain basic metabolic activities and annual herbaceous plants used the “shadow and avoid” response by increasing stem and root length to increase competitive ability. Under severe drought stress, planted seedling chlorophyll levels decreased, resulting in a simultaneous reduction in photosynthetic ability. The root growth of annual herbaceous plants depends on their photosynthesis ability but the decrease in biomass led to a decrease in root growth. The mixed habitat reduced the inhibition of seedling stem growth by drought stress and promoted plant growth.
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Glass, V. M., D. C. Percival, and J. T. A. Proctor. "Tolerance of lowbush blueberries (Vaccinium angustifolium Ait.) to drought stress. II. Leaf gas exchange, stem water potential and dry matter partitioning." Canadian Journal of Plant Science 85, no. 4 (October 1, 2005): 919–27. http://dx.doi.org/10.4141/p03-028.
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A 2-yr field study examining the effect of soil moisture on plant water status, photosynthesis and gas exchange parameters in lowbush blueberry (Vaccinium angustifolium Ait.) was conducted at the Nova Scotia Wild Blueberry Institute (NSWBI), Debert, NS. Drought and irrigation treatments were applied over two years in either or both the vegetative and cropping years of production. Midday stem water potential values indicated that all treatments resulted in drought stress. Mean stem water potential values ranged from -1.41 to -1.45 MPa. Predawn stem water potentials in the vegetative growth season indicated that although some recharging and recovery of water loss occurred overnight, the drought-stressed plants did not fully return to pre-stress levels under the moisture-limiting conditions. Higher chlorophyll a and b levels were observed in the single-season drought treatment. Leaves of irrigated plants in both sprout and crop years had the highest stomatal density. There were no differences in photosynthetic rate (Pn) among treatments despite the lower stomatal conductance resulting from limited soil moisture. Key words: Photosynthesis, stomate, stem water potential
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Jiang, Chaoqiang, Chaolong Zu, Jia Shen, Fuwen Shao, and Tian Li. "Effects of selenium on the growth and photosynthetic characteristics of flue-cured tobacco (Nicotiana tabacum L.)." Acta Societatis Botanicorum Poloniae 84, no. 1 (2015): 71–77. http://dx.doi.org/10.5586/asbp.2015.006.
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The objective of this study was to investigate the effect of Selenium (Se) supply (0, 3, 6, 12, 24 mg kg<sup>−1</sup>) on the growth, photosynthetic characteristics, Se accumulation and distribution of flue-cured tobacco (<em>Nicotiana tabacum</em> L.). Results showed that low-dose Se treatments (≤6 mg kg<sup>−1</sup>) stimulated plant growth but high-dose Se treatments (≥12 mg kg<sup>−1</sup>) hindered plant growth. Optimal Se dose (6 mg kg<sup>−1</sup>) stimulated plant growth by reducing MDA content and improving photosynthetic capability. However, excess Se (24 mg kg<sup>−1</sup>) increased MDA content by 28%, decreased net photosynthetic rate and carboxylation efficiency by 34% and 39%, respectively. The Se concentration in the roots, stems, and leaves of the tobacco plants significantly increased with increasing Se application. A linear correlation (<em>R</em> = 0.95, <em>P</em> < 0.01) was observed between Se level and tobacco plant tissue Se concentration. This correlation indicated that the tobacco plant tissues were not saturated within the concentration range tested. The pattern of total Se concentration in the tobacco plant tissues followed the order root > leaf > stem. The Se concentration in the roots was 3.17 and 7.57 times higher than that in the leaves and stems, respectively, after treatment with 24 mg kg<sup>−1</sup> Se. In conclusion, the present study suggested that optimal Se dose (6 mg kg<sup>−1</sup>) improved the plant growth mainly by enhancing photosynthesis, stomatal conductance, carboxylation efficiency and Rubisco content in the flue-cured tobacco leaves. However, the inhibition of excess Se on tobacco growth might be due to high accumulation of Se in roots and the damage of photosynthesis in leaves.
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Xu, Hui-lian, Laurent Gauthier, and André Gosselin. "Photosynthesis in Leaves, Fruits, Stem, and Petioles of Tomato Plants Grown in Peat Bags with Different Fertigation Management." HortScience 30, no. 4 (July 1995): 865A—865. http://dx.doi.org/10.21273/hortsci.30.4.865a.
Full textAbstract:
Tomato plants were grown in peat bags in greenhouse to examine the effects of variation of the nutrient solution electrical conductivity (EC) and substrate water potential (Ψsub) on photosynthesis in leaves, fruits, stem, and petioles. EC of the nutrient solution delivered to peat bags varied between 1 to 4 dS·m–1 with Ψsub of either –5 kPa or –9 kPa as the setpoint for starting the irrigation. The EC variation was adjusted by a computer system according to potential evapotranspiration. Gross photosynthetic capacity (PC) decreased as the leaf age developed. PC in the 10th, 15th and 18th leaves from the top was only 76%, 37%, and 18% of PC in the 5th leaf, respectively. However, low quantum use efficiency (QUE) was only observed in the 18th leaf and low dark respiration (RD) was only in 15th and 18th leaves. Net photosynthesis (PN) was only observed in young fruits (≈10 g FW) or young petioles and no PN was observed in large fruits (50 g or more FW) and stems. Both PC and RD were lower in older fruits and petioles or in the lower part of the stem compared to the younger ones or upper parts. EC variation increased PC, QUE, and RD in most parts. Low Ψsub increased RD in most parts and decreased PC in fruits, stem, and petioles. It is suggested that EC variation increased plant physiological activity of tomato and low Ψsub increased carbon consumption, although it was not severe enough to depress leaf PC.
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Currey, Christopher J., and Roberto G. Lopez. "Biomass Accumulation and Allocation, Photosynthesis, and Carbohydrate Status of New Guinea Impatiens, Geranium, and Petunia Cuttings Are Affected by Photosynthetic Daily Light Integral during Root Development." Journal of the American Society for Horticultural Science 140, no. 6 (November 2015): 542–49. http://dx.doi.org/10.21273/jashs.140.6.542.
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During the propagation of herbaceous stem-tip cuttings, the photosynthetic daily light integral (DLI) inside greenhouses can be low (≈1–4 mol·m−2·d−1) during the winter and early spring when propagation typically occurs. The mechanisms by which cuttings adapt biomass allocation patterns, gas exchange, and starch accumulation in response to the photosynthetic DLI are not clearly understood. Our objectives were to quantify the impact of DLI on growth, photosynthesis, and carbohydrate concentration during the root development phase of cutting propagation. Petunia (Petunia ×hybrida ‘Suncatcher Midnight Blue’), geranium (Pelargonium ×hortorum ‘Fantasia Dark Red’), and new guinea impatiens (Impatiens hawkeri ‘Celebration Pink’) cuttings were propagated in a glass-glazed greenhouse with 23 °C air and substrate temperature set points. After callusing (≈5 mol·m−2·d−1 for 7 days), cuttings of each species were placed under either no shade or one of the two different fixed-woven shade cloths providing ≈38% or 86% shade with 16 hours of supplemental light for 14 days, resulting in DLIs of 13.0‒14.2, 5.5‒6.0, and 2.0‒2.4 mol·m−2·d−1, respectively. Leaf, stem, and root biomass accumulation increased linearly with DLI by up to 122% (geranium), 118% (petunia), and 211% (new guinea impatiens), as DLI increased by ≈11‒12 mol·m−2·d−1, while relative biomass allocation into roots increased under increasing DLI. Compared with cuttings rooted under low DLIs (2.0‒2.4 mol·m−2·d−1), cuttings of all three species generally had greater maximum gross photosynthesis under high DLIs (13.0‒14.2 mol·m−2·d−1) starting 5 or 8 days after transfer. Starch concentration increased with DLI by up to 946% (impatiens) during propagation. Taken together, the increased growth of cuttings appears to be a result of increased carbohydrate availability from elevated photosynthesis and/or photosynthetic capacity.
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Fu, Zhenzhu, Craig E. Martin, Jeney Do, Che-Ling Ho, and Babs Wagner. "Functional relationship between leaf/stem pseudobulb size and photosynthetic pathway in the Orchidaceae." Canadian Journal of Plant Science 102, no. 2 (April 1, 2022): 419–26. http://dx.doi.org/10.1139/cjps-2020-0311.
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Water storage has been commonly cited as an important function of orchid pseudobulbs, and it is reasonable to assume that orchids which utilize crassulacean acid metabolism (CAM) photosynthesis have larger pseudobulbs than those of C3 orchid taxa, because these foliar (or stem) structures may reflect another type of succulent tissue in CAM plants. On the other hand, it is equally plausible that C3 orchids have larger pseudobulbs, as they lack succulent tissue, as well as the water-conservative CAM pathway. The goal of this study was to compare pseudobulb size in over 100 living orchid species growing at the Missouri Botanical Garden by measurement. Pseudobulb volumes of C3 species did not differ from those of species with CAM photosynthesis in a family-wide comparison of all sampled species, as well as in comparisons of taxa with these two photosynthetic pathways among three subtribes and within one genus. The results did not support a functional relationship between pseudobulb volume and photosynthetic pathway in the Orchidaceae. Pseudobulbs are equally important structures in C3 and CAM orchid taxa, and may function similarly in water, carbohydrates, and (or) essential elements storage in the two groups of orchids. This study lays a foundation for further research into pseudobulb evolution in orchids.
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Schneller*, Katrina L., Bert Cregg, and Grant Jones. "Growth and Physiological Response of Nursery-grown Landscape Trees to Fertigation." HortScience 39, no. 4 (July 2004): 892E—893. http://dx.doi.org/10.21273/hortsci.39.4.892e.
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Thirteen species of shade trees including four oak and three maple species were planted from bare root whips in Spring 2001 at the Michigan State Univ. horticulture station near Benton Harbor, Mich. Forty trees of each species were planted and placed under a randomized complete block design consisting of four fertigation treatments in a 2 × 2 factorial (with and without irrigation; with and without nitrogen fertilization). Fertilized trees received 168 kg per hectare of ammonium nitrate annually via the drip system. We measured tree height, stem diameter, and stem volume index (D2 H) at the end of each growing season. We also measured photosynthetic gas exchange with a portable photosynthesis system. After three growing seasons irrigation increased stem volume and height growth. Fertilization has not increased stem volume and height growth, yet there is an interaction between irrigation and fertilization meaning that among irrigated trees fertilizer produced significantly more growth. Species effect on growth was significant (P < 0.001); honey locust trees have grown the most with an average height increase of 1.28 meters in 2003. `Crimson King' Norway maple and goldenchain trees grew the least averaging less than.305 meters of height growth per year. There is no interaction between species and fertigation responses meaning that all species had similar responses to the treatments. From light response curves obtained with a portable photosynthesis system Amax (maximum rate of CO2 assimilation) varied significantly by species and treatment, but showed no interaction between species and treatment effects. Implications for the nursery industry along with further photosynthetic responses will be discussed.
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Chen, Ke, Song Mei Shi, Xiao Hong Yang, and Xian Zhi Huang. "Contribution of Arbuscular Mycorrhizal Inoculation to the Growth and Photosynthesis of Mulberry in Karst Rocky Desertification Area." Applied Mechanics and Materials 488-489 (January 2014): 769–73. http://dx.doi.org/10.4028/www.scientific.net/amm.488-489.769.
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The photosynthesis effect of arbuscular mycorrhizal fungi (AMF) on mulberry was evaluated in karst rocky desertification area. Three-month-old sterile mulberry saplings were transplanted in karst rocky desertification area and were inoculated with Gigaspora rosea. Some growth parameters and photosynthesis indexes were measured to study the physiological responses after inoculating for 1 year. The results showed mulberries that were inoculated with AMF had greater height, larger stem diameter and leaf area, more leaf number per plant, more fibrous root number and biomass of shoots and roots, as well as higher chlorophyll content, net photosynthetic rate, transpiration rate, stomatal conductance compared with non-AMF plants. The research results confirmed that AMF markedly enhanced the absorptive ability of root system, promoted the vegetative growth, improved the photosynthetic capacity, and obviously increased mulberry survival rate in karst rocky desertification area. These results provided a theoretical base for the ecological restoration in karst rocky desertification area.
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Williams, David G., and R. Alan Black. "Effects of nutrient amendment and environment on growth and gas exchange for introduced Penniseturn setaceum in Hawaii." Canadian Journal of Botany 74, no. 2 (February 1, 1996): 268–75. http://dx.doi.org/10.1139/b96-032.
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We examined the effects of a balanced soil nutrient amendment on photosynthesis, growth, and reproduction for the alien grass Penniseturn setaceum across an altitudinal gradient on the island of Hawaii. Nutrient amendment of plants enhanced aboveground growth, height, and numbers of reproductive tillers and inflorescences similarly across the altitudinal gradient. Nutrient amendment increased aboveground biomass 22 to 25% but had little effect on predawn water potential, leaf nitrogen concentration, or photosynthesis. Leaf nitrogen concentrations declined with altitude (22 ± 0.5 mg/g N at the coastal site; 16 ± 0.1 mg/g N at the subalpine site) and partially compensated for decreases in specific leaf area with altitude. Plants at the subalpine site had high dark respiration rates, low CO2 saturated photosynthetic rates, and low photosynthetic nitrogen use efficiencies compared with plants at lower altitudes. Chilling temperatures or high respiratory rates may limit net carbon uptake and growth for plants at higher altitude relative to plants at lower altitude. Seasonal patterns of net photosynthesis, stomatal conductance, and water potential suggest that drought colimited carbon uptake and growth at the low altitude site. Success of Penniseturn in Hawaii may stem, in part, from its ability to respond morphologically to compensate for heterogeneous nutrient and water availability across different habitats. Keywords: altitude, Hawaii, nutrient amendment, photosynthesis, Penniseturn setaceum, resource limitation.
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ARDHANA, I. PUTU GEDE, I. M. G. S. RIMBAWAN, PUJO NUR CAHYO, YUYUN FITRIANI, and SISKA ROHANI. "The distribution of vertical leaves and leaves biomass on ten mangrove species at Ngurah Rai Forest Park, Denpasar, Bali, Indonesia." Biodiversitas Journal of Biological Diversity 19, no. 3 (May 1, 2018): 918–26. http://dx.doi.org/10.13057/biodiv/d190322.
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Ardhana IPG, Rimbawan IMGS., Cahyo PN, Fitriani Y, Rohani S. 2018. The distribution of vertical leaves and leaves biomass on ten mangrove species at Ngurah Rai Forest Park, Denpasar, Bali, Indonesia. Biodiversitas 19: 918-926. The distribution of vertical leaves and leaves biomass which forms the mangrove crown divides into three parts, namely the top part, the middle part, and the bottom part. Total amount leaves on any parts are highly variable depending on height of each species. The relationship between the height of tree with the crown thickness depended on total leaves of each crown on each species as well as the relationship between the total leaves biomass of each crown on each species, with the height and volume of tree stems, also has variation on each mangrove species. Author examined the relationship between the photosynthetic organs with non-photosynthetic organs, especially on stems in each species. The high total amount of leaves and large total amount leaves biomass deeply is depended on diameter and growth height which are presented in the form of stem volumes. On the relationship between the photosynthetic organs and non-photosynthetic organs on each mangrove species, also has been examined. The higher total amount of leaves or the total amount of leaves biomass largely depended on the stem volume of mangroves. This indicates that the production of photosynthetic organ either in the form of the total amount of leaves or the total amount of leaves biomass serve to support growth of the stem mangrove trees (height of stem, diameter of stem and volume of stem).
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Letts, Matthew G., Davin R. E. Johnson, and Craig A. Coburn. "Drought stress ecophysiology of shrub and grass functional groups on opposing slope aspects of a temperate grassland valley." Botany 88, no. 9 (September 2010): 850–66. http://dx.doi.org/10.1139/b10-054.
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Plant functional groups with contrasting growth strategies co-occur in semiarid ecosystems. In the northern Great Plains, woody shrubs and grasses interact competitively, with shrubs prevalent on mesic hillslopes. To understand topographic influences on physiological drought acclimation, we measured seasonal photosynthetic water use in C3 shrubs ( Artemisia cana Pursh and Rhus trilobata Nutt.) and grasses ( Agropyron cristatum (L.) Gaertn. and Stipa viridula Trin.) on north- and south-facing slopes. Relationships between abiotic controls and photosynthesis were similar on both aspects, indicating an absence of long-term photosynthetic acclimation to xeric, south-facing conditions. Acclimatory differences were observed between functional groups. Soil moisture depletion lowered intercellular:atmospheric CO2 ratio (Ci/Ca) and increased intrinsic water-use efficiency (WUEi = Amax/gs) in shrubs, but not grasses. Consequently, between-slope differences in net photosynthesis (Amax) and stomatal conductance (gs) occurred only in shrubs, with lower values on the south-facing slope. Shrubs also exhibited between-slope differences in the photochemical reflectance index, suggesting drought-related photoprotection. The deuterium:hydrogen ratios of stem water showed that deep water use facilitated late summer growth in shrubs. Consistent with plant distribution, cumulative water use and photosynthesis were higher in shrubs than in grasses on the north-facing slope, but higher in grasses than in shrubs on the south-facing slope. This shows that topographic effects on leaf photosynthetic gas exchange are mediated by physiological acclimation strategy and water source use.
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Hou, Yong Xia, Xiao Jun Hu, Yu Shuang Li, Xue Ying Song, Hong Liang Chen, and Ji Song Yang. "Effect of Mushroom Residue Used in Washed Soil on the Growth of Tomatoes." Advanced Materials Research 726-731 (August 2013): 90–93. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.90.
Full textAbstract:
In order to reveal the regulating capacity of mushroom residue on washed soil, pots experiments were carried out. The growth of tomatoes planted on washed soil amended by mushroom residue were measured. Mushroom residue can be helpful to improve the plant height, stem diameter, the aerial parts fresh weight, root fresh weight, leaf photosynthetic rates and photosynthesis, and lay a good foundation for the growth of tomatoes. The effect of mushroom residue is the most significant. Among all the treatments of adding 2.5%, 5%, 10% mushroom residue, adding 10% mushroom residue is the best. It can significantly enhance the growth and photosynthesis of tomatoes, and is among the best of these three soil treatments for washed soil.
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Hou, Yong Xia, Jing Yang, Xiao Jun Hu, Yu Shuang Li, Xue Ying Song, and Ji Song Yang. "Effect of Organic Fertilizers Used in Washed Soil on the Growth of Tomatoes." Advanced Materials Research 1010-1012 (August 2014): 576–79. http://dx.doi.org/10.4028/www.scientific.net/amr.1010-1012.576.
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Abstract. In order to reveal the regulating capacity of organic fertilizers on washed soil, pots experiments were carried out. The growth of tomatoes planted on washed soil amended by organic fertilizers were measured. Organic fertilizers can be helpful to improve the plant height, stem diameter, the aerial parts fresh weight, root fresh weight, leaf photosynthetic rates and photosynthesis, and lay a good foundation for the growth of tomatoes. The effect of organic fertilizers is the most significant. Among all the treatments of adding 2.5%, 5%, 10% organic fertilizers, adding 10% organic fertilizers is the best. It can significantly enhance the growth and photosynthesis of tomatoes, and is among the best of these three soil treatments for washed soil.
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Macedo, Tulio B., David K. Weaver, and Robert K. D. Peterson. "Photosynthesis in Wheat at the Grain Filling Stage Is Altered by Larval Wheat Stem Sawfly (Hymenoptera: Cephidae) Injury and Reduced Water Availability." Journal of Entomological Science 42, no. 2 (April 1, 2007): 228–38. http://dx.doi.org/10.18474/0749-8004-42.2.228.
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The impact of larval feeding by wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), and reduced water availability on the photosynthesis and primary metabolism of wheat, Triticum aestivum (L.), was evaluated at the grain-filling developmental stage. Photosynthetic parameters measured included photosynthesis (Ps), stomatal conductance (gs), and transpiration (E) in the flag leaves. The parameters were measured at 4 wks after the treatments were imposed. Additional concomitant chlorophyll a fluorescence measurements were taken using both dark- and light-adapted tests. Photosynthesis was significantly affected by C. cinctus injury and suboptimal water availability. However, no significant interaction was observed between the two treatment factors. Plants under a reduced or suboptimal watering regime had Ps rates that were 43.7% lower than plants that were watered daily. We also observed a 12% higher Ps rate in uninfested plants compared to plants infested by C. cinctus. Several chlorophyll a fluorescence parameters also were affected by C. cinctus. Specifically, reductions in the photochemical efficiency of photosystem II (PSII) of C. cinctus infested plants were observed for plants under reduced water availability. This study demonstrates that wheat plants at the grain filling stage have reduced photosynthetic capacity when watered less frequently or when subjected to C. cinctus larval feeding injury. Less frequent watering and larval feeding injury did not have significant impacts on yield in this greenhouse study.
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Foster, William J., Dewayne L. Ingram, and Terril A. Nell. "Photosynthesis and Root Respiration in Ilex crenata `Rotundifolia' at Supraoptimal Root-zone Temperatures." HortScience 26, no. 5 (May 1991): 535–37. http://dx.doi.org/10.21273/hortsci.26.5.535.
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Rooted stem cuttings of Ilex crenata Thunb. `Rotundifolia' were grown in a controlled-environment growth chamber. Root-zone temperatures were controlled with an electric system. Shoot carbon exchange and root respiration rates were determined in response to root-zone temperatures of 28, 32, 36, and 40C for 6 hour·day–1 for 7 days. Photosynthesis was decreased by root zones ≥ 32C, while root respiration increased with increasing root-zone temperature. Decreased photosynthetic rates were not due to increased stomatal resistance.
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Xu, Mingyuan, Yingwei Wang, Qianbo Wang, Shenglei Guo, Yang Liu, Jia Liu, Zhonghua Tang, and Zhenyue Wang. "Changes in Growth and Photosynthetic Parameters and Medicinal Compounds in Eleutherococcus senticosus Harms under Drought Stress." HortScience 54, no. 12 (December 2019): 2202–8. http://dx.doi.org/10.21273/hortsci14366-19.
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In this investigation, changes in growth and photosynthetic parameters were used to explain the effects of drought stress on morphology and photosynthesis of Eleutherococcus senticosus. Liquid chromatography (LC)-mass spectroscopy (MS) was used to determine the content of eleutheroside B, eleutheroside E, isofraxidin, hyperoside, rutin, and kaempferol under different drought stress conditions to explain the effects of drought stress on secondary metabolism of Eleuthero. Growth and photosynthetic physiological parameters showed that drought stress could inhibit the growth and photosynthesis of Eleuthero. The compounds studied showed the same cumulative trend in various organs of Eleuthero under different drought stress conditions, with the highest content in the moderate drought stress group and the lowest in the severe drought stress group. Among them, the content of eleutheroside B was found to be higher in the 5-year-old stem. The content of eleutheroside E was higher in the 3-year root. The content of isofraxidin was highest in the 5-year-old root. The content of hyperoside, rutin, and kaempferol were higher in the 3-year-old leaves. The results show that a wet soil environment was beneficial to growth and photosynthesis of Eleutherococcus senticosus, and moderate drought stress is conducive to the accumulation of its active ingredients.
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Mercado, Lina M., Sandra Patiño, Tomas F. Domingues, Nikolaos M. Fyllas, Graham P. Weedon, Stephen Sitch, Carlos Alberto Quesada, et al. "Variations in Amazon forest productivity correlated with foliar nutrients and modelled rates of photosynthetic carbon supply." Philosophical Transactions of the Royal Society B: Biological Sciences 366, no. 1582 (November 27, 2011): 3316–29. http://dx.doi.org/10.1098/rstb.2011.0045.
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The rate of above-ground woody biomass production, W P , in some western Amazon forests exceeds those in the east by a factor of 2 or more. Underlying causes may include climate, soil nutrient limitations and species composition. In this modelling paper, we explore the implications of allowing key nutrients such as N and P to constrain the photosynthesis of Amazon forests, and also we examine the relationship between modelled rates of photosynthesis and the observed gradients in W P . We use a model with current understanding of the underpinning biochemical processes as affected by nutrient availability to assess: (i) the degree to which observed spatial variations in foliar [N] and [P] across Amazonia affect stand-level photosynthesis; and (ii) how these variations in forest photosynthetic carbon acquisition relate to the observed geographical patterns of stem growth across the Amazon Basin. We find nutrient availability to exert a strong effect on photosynthetic carbon gain across the Basin and to be a likely important contributor to the observed gradient in W P . Phosphorus emerges as more important than nitrogen in accounting for the observed variations in productivity. Implications of these findings are discussed in the context of future tropical forests under a changing climate.
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David-Assael, Ora, Irina Berezin, Noa Shoshani-Knaani, Helen Saul, Talya Mizrachy-Dagri, Jianxin Chen, Emil Brook, and Orit Shaul. "AtMHX is an auxin and ABA-regulated transporter whose expression pattern suggests a role in metal homeostasis in tissues with photosynthetic potential." Functional Plant Biology 33, no. 7 (2006): 661. http://dx.doi.org/10.1071/fp05295.
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AtMHX is a vacuolar transporter encoded by a single gene in Arabidopsis thaliana (L.) Heynh. It exchanges protons with Mg2+, Zn2+, and Fe2+ ions. Proper homeostasis of these metals is essential for photosynthesis and numerous enzymatic reactions. In particular, very little is known about mechanisms involved in Mg2+ homeostasis in plants. Expression analysis using reporter-gene constructs suggested that AtMHX functions in metal homeostasis mainly in tissues with photosynthetic potential. This balancing is conducted by expression in the vascular region, the cortex of stems, trichomes, and hydathodes. Expression in stems is developmentally regulated, suggesting that minerals are accumulated in the upper regions of young stems, and are released during silique development. Mineral content in different stem parts was consistent with this possibility. Expression was induced by auxin and ABA, but not by the metal content of the growth medium, suggesting that expression is mainly regulated by endogenous developmental programs. AtMHX exhibits two distinguished regulatory properties. Its leader intron is absolutely essential for expression, and mediates an 86-fold enhancement of expression. This enhancement is the highest reported thus far for any dicot intron. Another remarkable feature is that a repetitive genomic element of 530 bp (or part of it) functions as an enhancer.
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Zhang, Shubin, Guojing Wen, and Daxin Yang. "Drought-Induced Mortality Is Related to Hydraulic Vulnerability Segmentation of Tree Species in a Savanna Ecosystem." Forests 10, no. 8 (August 17, 2019): 697. http://dx.doi.org/10.3390/f10080697.
Full textAbstract:
Vulnerability segmentation (VS) has been widely suggested to protect stems and trunks from hydraulic failure during drought events. In many ecosystems, some species have been shown to be non-segmented (NS species). However, it is unclear whether drought-induced mortality is related to VS. To understand this, we surveyed the mortality and recruitment rate and measured the hydraulic traits of leaves and stems as well as the photosynthesis of six tree species over five years (2012–2017) in a savanna ecosystem in Southwest China. Our results showed that the NS species exhibited a higher mortality rate than the co-occurring VS species. Across species, the mortality rate was not correlated with xylem tension at 50% loss of stem hydraulic conductivity (P50stem), but was rather significantly correlated with leaf water potential at 50% loss of leaf hydraulic conductance (P50leaf) and the difference in water potential at 50% loss of hydraulic conductance between the leaves and terminal stems (P50leaf-stem). The NS species had higher Huber values and maximum net photosynthetic rates based on leaf area, which compensated for a higher mortality rate and promoted rapid regeneration under the conditions of dry–wet cycles. To our knowledge, this study is the first to identify the difference in drought-induced mortality between NS species and VS species. Our results emphasize the importance of VS in maintaining hydraulic safety in VS species. Furthermore, the high mortality rate and fast regeneration in NS species may be another hydraulic strategy in regions where severe seasonal droughts are frequent.
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Żelawski, W., J. Kucharska, and J. Kinelska. "Relationship between dry matter production and carbon dioxide absorption in seedlings of Scots pine (Pinus silvestris L.) in their second vegetation season." Acta Societatis Botanicorum Poloniae 40, no. 2 (2015): 243–56. http://dx.doi.org/10.5586/asbp.1971.015.
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Accumulation of dry matter in needles, lignified stems and roots during the second vegetation season was compared with seasonal changes in photosynthesis and respiration activities of the se organs. Whereas growth analysis concerned plants growing at nearly natural course of external conditions, gas exchange determinations were made at constant laboratory conditions. For comparison of dry matter production and photosynthetic ability of a plant new terms „assimilation capacity" and „efficiency of assimilation" were introduced as possible expressions of photosynthetic productivity. Two ecotypes of Scots pine originating from lowland and highland regions of the country exhibited slightly different pattern of the investigated characteristics.
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Colodetti, Tafarel Victor, Wagner Nunes Rodrigues, Paulo Cezar Cavatte, Edvaldo Fialho dos Reis, Abraão Carlos Verdin Filho, Sebastião Vinícius Batista Brinate, Lima Deleon Martins, Bruno Fardim Christo, Saul de Andrade Júnior, and Marcelo Antonio Tomaz. "Managing the number of orthotropic stems in Coffea arabica as strategy for cultivation at low-altitude regions." March 2020, no. 14(03):2020 (March 20, 2020): 447–54. http://dx.doi.org/10.21475/ajcs.20.14.03.p1986.
Full textAbstract:
The objective of this study was to better understand the implications of the management of the number of orthotropic stems in Arabica coffee for its cultivation in low-altitude regions (< 500 m), characterizing its effects over the canopy architecture, production and allocation of biomass, photosynthesis and crop yield, as possible strategy for mitigating the stresses of cultivation at low-altitude regions. The experiment was conducted in a region with 124 m of elevation above sea level, studying four treatments with different numbers of orthotropic stems per plant such as one, two, three and four stems. After planting, during the stage of sprout budding, a number of sprouts were established in accordance to the treatments. The experimental design was a randomized block design, with eight repetitions. Parameters of gas exchange, chlorophyll contents, canopy architecture, production and allocation of biomass, and crop yield were evaluated to characterize the plant development. Overall, increasing the number of orthotropic stems per plant promoted leaf density, number of plagiotropic branches per plant, available leaf area per fruit mass, photosynthetic rate, crop yield, proportion of large grains and, possibly, the de-acceleration of the stem aging rate, mainly for the management with four orthotropic stems. It is concluded that the management of the number of orthotropic stems has potential use as a mitigator for the cultivation of Arabica coffee in low-altitude regions, being able to promote higher canopy density and, possibly, enhance microclimate conditions at the canopy level.
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Chongo, G., and P. B. E. McVetty. "Relationship of physiological characters to yield parameters in oilseed rape (Brassica napus L.)." Canadian Journal of Plant Science 81, no. 1 (January 1, 2001): 1–6. http://dx.doi.org/10.4141/p00-012.
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The physiological basis of seed yield in oilseed rape (Brassica napus L.) still remains unclear, and conclusions on the contribution of such traits to seed yield are difficult to make. Nine cultivars, classified into three yield groups (high, medium and low) based on significant differences in seed yield from previous trials, were tested over two locations and years. Leaf chlorophyll content, net photosynthetic rate per unit leaf area (PA), per unit leaf dry matter (PDM) and per unit leaf chlorophyll (PC), transpiration rate (TR) and water use efficiency (WUE) were investigated on fully expanded leaf numbers 4 (vegetative), 6 (early flowering) and 8 (early podding stage) on the main stem and related to seed yield, total dry matter (TDM) and harvest index (HI) of each yield group. Differences among yield groups for seed yield, TDM and HI were significant. Chlorophyll content was lowest on leaf 4, but increased with leaf age. Correlations between net photosynthetic rate and seed yield were not found. However, cultivars in the high yield group maximized their net photosynthetic rates (PA, PDM, and PC) on leaf 6 during early flowering at the time when TR was lowest and WUE at its highest. In the medium and low groups, photosynthetic rates were highest on leaf 4, but decreased to lowest values on leaf 8, together with the high yield group. In general, the results indicate that the largest contribution to net photosynthesis by oilseed rape leaves occurred during the vegetative and early flowering stages compared with the early pod-filling stage. Key words: Total dry matter, harvest index, photosynthesis, chlorophyll
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RINDYASTUTI, RIDESTI, DIAH RACHMAWATI, RETNO PENI SANCAYANINGSIH, and TITUT YULISTYARINI. "Ecophysiological and growth characters of ten woody plant species in determining their carbon sequestration." Biodiversitas Journal of Biological Diversity 19, no. 2 (March 1, 2018): 610–19. http://dx.doi.org/10.13057/biodiv/d190238.
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Rindyastuti R, Rachmawati D, Sancayaningsih RP, Yulistyarini T. 2018. Ecophysiological and growth characters of ten woody plant species in determining their carbon sequestration. Biodiversitas 19: 610-619. Tree planting and ecosystem restoration is one of mitigation program of global climate change scheme to reduce CO2 in the atmosphere by sequestering carbon. Carbon storage in the living plant varies among species due to ecophysiological and growth characters of their photosynthesis. Ecophysiological properties of tropical plant species related to carbon sequestration was lack of investigation. The study in this area will be the significant knowledge contribution to C-sink project especially species-level management which has been agreed globally and nationally. The objectives of this research were to study the ecophysiological and growth factors affecting carbon sequestration and to select plant species with high carbon sequestration using 16 months-old-seedling of ten woody plant species. Biomass, carbon storage, the whole plant photosynthetic capacity, total chlorophyll content, stomatal index, and Leaf Area Index (LAI) were significantly different among species. The LAI, total chlorophyll content, whole plant photosynthetic capacity, stem height and stem diameter were positively correlated to biomass and carbon storage. Multivariate correlation test (P>0.05) revealed that the total of chlorophyll content was the ecophysiological factor most contributes to carbon sequestration. The total of chlorophyll content correlates to the stem height, while the whole plant photosynthesis correlates to leaf area in determining plant carbon sequestration. Moreover, two mangrove species, H. littoralis and B. asiatica have the highest carbon sequestration among species studied. For priority in tree planting program in dry lowland habitats, the local species, i.e., S. cumini and D. discolor were more recommended than any others species observed in this study.
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Maydup, Maria L., Mariana Antonietta, Nicolás Rouillet, Maria G. Cano, Juan J. Guiamet, and Eduardo A. Tambussi. "Methodological aspects and impact on grain weight of source reduction through shade meshes during grain filling of bread wheat." Crop and Pasture Science 71, no. 8 (2020): 739. http://dx.doi.org/10.1071/cp18565.
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In crop studies, shading is a common approach for reducing source activity (i.e. assimilates produced by photosynthesis); however, if source reduction is not directly proportional to the degree of light attenuation, estimations could be flawed. We analysed the effects of shading at three levels on light transmittance, air and canopy temperatures, and actual photosynthetic activity at different times of day, and on grain weight in a modern genotype of bread wheat (Triticum aestivum L.). The treatments were imposed 10 days after anthesis and comprised three levels of shading with meshes: 80%, 50% and 10% transmittance during midday. The decrease in midday photosynthetic activity (electron transport rate, ETR; and CO2 assimilation, An) in the shading treatments compared with control plants did not fit a 1:1 relationship with light transmittance of the meshes; for example, the reduction in ETR and An was <50% under the mesh with 50% light transmittance. The decrease in light transmittance and photosynthesis caused by the meshes was higher during the morning and afternoon than midday. In the grain-filling period, midday ETR showed a progressive, age-dependent decrease in control plants compared with shading treatments. Initial differences in photosynthetic activity between treatments were attenuated throughout the grain-filling period. The diurnal course of air temperature showed a progressive decrease from control to shade treatments, mainly during midday. This pattern was confirmed by infrared thermometry of canopy temperature, with severe shade showing the lowest temperature. Greenness measurements at 19 days after anthesis showed delayed senescence in shaded plants, possibly due to the decrease in temperature under shade. Grain weight per ear was reduced in shading treatments (mainly with 50% and 10% light transmittance). The decrease in grain weight per ear plotted against the decrease in photosynthesis (evaluated through ETR or An) did not fit a 1:1 relationship. This could be explained in part by an observed increase in dry matter retranslocation from the stem. In summary, estimations of source reduction on the basis of light attenuation could be biased, because the photosynthesis decrease is less than proportional, and photosynthesis differences are attenuated throughout grain filling.
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Greer, Dennis H., and Sylvie M. Sicard. "The net carbon balance in relation to growth and biomass accumulation of grapevines (Vitis vinifera cv. Semillon) grown in a controlled environment." Functional Plant Biology 36, no. 7 (2009): 645. http://dx.doi.org/10.1071/fp09037.
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Assessing the impacts of environmental stresses on plant growth and productivity requires an understanding of the growth processes and the carbon economy that underpins this growth. Potted grapevines of the Vitis vinifera L. cv. Semillon were grown in a controlled environment and canopy growth; leaf, bunch and stem extension and net photosynthesis were routinely measured from budbreak to harvest. Allometric relationships enabled dry matter to be determined and, with net photosynthesis, used to determine the shoot carbon economy. Stems, leaves and bunches all followed a sigmoid growth pattern with leaves and stems allocated similar amounts of biomass and carbon while bunches had twice as much. Rates of carbon sequestered as biomass exceeded rates of carbon acquisition through net photosynthesis for over 25 days after budbreak. Despite the high demand for biomass in bunch growth, rates of carbon sequestration actually declined and overall, the vines maintained a positive carbon balance throughout the period of bunch growth. The Semillon shoots relied on carbon reserves to commence growth then produced a 53% carbon surplus after leaf (9%), stem (10%) and bunch (28%) growth demands were satisfied. This suggests these vines also allocated carbon to reserves to sustain the next season’s growth.
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Heins, Royal D., Meriam G. Karlsson, J. A. Flore, and William H. Carlson. "Effects of Photosynthetic Rate Maximization on Chrysanthemum Growth and Development." Journal of the American Society for Horticultural Science 111, no. 1 (January 1986): 42–46. http://dx.doi.org/10.21273/jashs.111.1.42.
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Abstract A 2nd order equation relating net photosynthesis (Pn) to photosynthetic photon flux density (PPFD), temperature, and CO2 was determined from single leaf CO2 depletion measurements made with an open gas analysis system. From this information, a photosynthetic optimization equation was used as the basis for computer regulation of greenhouse environment control using 2 strategies. In strategy 1, both temperature and CO2 setpoints were reset every 15 min based on the PPFD in the greenhouse. In strategy 2, only the temperature setpoint was reset, CO2 was ambient. The calculated setpoints represented temperature and/or CO2 values, where predicted Pn was maximized at the particular PPFD. Both strategies were compared to a typical commercial chrysanthemum environment of 16/20/24°C (night/day/vent) with ambient CO2. Chrysanthemum morifolium Ramat. (‘Bright Golden Anne’) grown in the temperature and CO2 optimized environment had significantly greater leaf, stem, and total dry weight at flowering compared to the other 2 environmental strategies. The percentage of stem dry weight and the stem length also were increased. For all 3 planting dates the percentage of flower dry weight was reduced but statistically significant on 1 date only. Flowering date was not affected. No consistent statistical differences in plant development were observed between the temperature optimized environment and the traditional environment.
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Tambussi, Eduardo A., María L. Maydup, Cristian A. Carrión, Juan J. Guiamet, and Jose L. Araus. "Ear photosynthesis in C3 cereals and its contribution to grain yield: methodologies, controversies, and perspectives." Journal of Experimental Botany 72, no. 11 (March 25, 2021): 3956–70. http://dx.doi.org/10.1093/jxb/erab125.
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Abstract In C3 cereals such as wheat and barley, grain filling was traditionally explained as being sustained by assimilates from concurrent leaf photosynthesis and remobilization from the stem. In recent decades, a role for ear photosynthesis as a contributor to grain filling has emerged. This review analyzes several aspects of this topic: (i) methodological approaches for estimation of ear photosynthetic contribution to grain filling; (ii) the existence of genetic variability in the contribution of the ear, and evidence of genetic gains in the past; (iii) the controversy of the existence of C4 metabolism in the ear; (iv) the response of ear photosynthesis to water deficit; and (v) morphological and physiological traits possibly related to ear temperature and thermal balance of the ear. The main conclusions are: (i) there are a number of methodologies to quantify ear photosynthetic activity (e.g. gas exchange and chlorophyll fluorescence) and the contribution of the ear to grain filling (individual ear shading, ear emergence in shaded canopies, and isotope composition); (ii) the contribution of ear photosynthesis seems to have increased in modern wheat germplasm; (iii) the contribution of the ear to grain filling increases under resource-limitation (water deficit, defoliation, or pathogen infection); (iv) there is genetic variability in the contribution of the ear in wheat, opening up the possibility to use this trait to ameliorate grain yield; (v) current evidence supports the existence of C3 metabolism rather than C4 metabolism; (vi) the ear is a ‘dehydration avoider organ’ under drought; and (vii) thermal balance in the ear is a relevant issue to explore, and more research is needed to clarify the underlying morphological and physiological traits.
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Wang, Mingqi, and Lixin Peng. "Development of Indexes to Evaluate Hardiness of Rose Germplasm." HortScience 31, no. 4 (August 1996): 645c—645. http://dx.doi.org/10.21273/hortsci.31.4.645c.
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Physiological, biochemical and anatomical indexes were investigated for rose hardiness. It was found that bound/free water ratio, proline accumulation, photosynthetic rate, palisade/spongy tissue ratio, and lignification of winter-acclimated stems were heavily influenced by the temperature causing stem browning. Spongy cell volume and stem tenderness were inversely related to winter hardiness. Data generated from this research demonstrated that catalase stability, TTC reduction rate at 0°C, total photosynthetic rate, stem pith ray number, and leaf wax thickness are good indicators for rose hardiness to freezing temperatures. Two compound indexes were developed through the main component analysis. Based on the results obtained from 12 tested cultivars, these indexes are ideal to quantify hardiness of rose germplasm.
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Smalley, T. J., M. A. Dirr, A. M. Armitage, B. W. Wood, R. O. Teskey, and R. F. Severson. "Photosynthesis and Leaf Water, Carbohydrate, and Hormone Status during Rooting of Stem Cuttings of Acer rubrum." Journal of the American Society for Horticultural Science 116, no. 6 (November 1991): 1052–57. http://dx.doi.org/10.21273/jashs.116.6.1052.
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Leaf water status, carbohydrate levels, net photosynthesis, stomatal conductance, ABA, dihydrozeatin riboside (DHZR), and trans-zeatin riboside (ZR) levels were determined in a greenhouse during rooting of stem cuttings of Acer rubrum L. `Red Sunset' taken on 3 Sept. 1987 and 28 May 1988. Leaf water status deteriorated before rooting and improved after root emergence. Leaf carbohydrate concentrations (glucose, sucrose, total soluble sugars, and total carbohydrates) increased until rooting and decreased after rooting, while changes in starch concentrations were trendless. ABA levels increased after insertion of cuttings into the rooting medium, but decreased before rooting. No correlation between timing of rooting and concentrations of the cytokinins ZR or DHZR was observed. Photosynthetic rates during rooting were higher for the Sept. 1987 cuttings and did not decrease to the compensation point as did those for May 1988 cuttings. Low photosynthetic rates and stomatal conductance of the cuttings during rooting were associated with water stress. The relationship between photosynthetic rates of such cuttings and cytokinin (CK) or ABA content was unclear. Chemical names used: [S-(Z,E]-5-(1-hydroxy-2,6,6-trimethyl-4-oxo-2-cyclohexen-1-yl)-3-methyl-2, 4-pentadienoic acid (abscisic acid, ABA); 2-methyl-4-(1H-purin-6-ylamino)-2-buten-1-ol (zeatin, Z).
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Rivera-Amado, Carolina, Gemma Molero, Eliseo Trujillo-Negrellos, Matthew Reynolds, and John Foulkes. "Estimating Organ Contribution to Grain Filling and Potential for Source Upregulation in Wheat Cultivars with a Contrasting Source–Sink Balance." Agronomy 10, no. 10 (October 8, 2020): 1527. http://dx.doi.org/10.3390/agronomy10101527.
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Grain filling may be limited by the joint source and sink capacity in modern wheat cultivars, indicating a need to research the co-limitation of yield by both photosynthesis and the number and potential size of grains. The extent to which the post-anthesis source may be limiting final grain size can be estimated by partial degraining of spikes, while defoliation and shading treatments can be useful to estimate if any excess photosynthetic capacity exists. In the current study, degraining was applied to a set of 26 elite spring wheat cultivars from the International Maize and Wheat Improvement Center (CIMMYT)’s core germplasm (CIMCOG) panel, while lamina defoliation and shading through stem-and-leaf-sheath covering treatments were applied to a subset of the same cultivars. Responses to source treatments in grain weight, pre-anthesis reserve contribution to grain weight, dry-matter translocation efficiency, and flag-leaf and spike photosynthetic rate were measured and compared to an unmanipulated control treatment. Grain weight responses to degraining among cultivars ranged from no response to increases of 28%, suggesting a range of responses from sink limitation, to probable source and sink co-limitation of grain growth. Grain weight’s response to degraining increased linearly with the years of cultivar release from 1966 to 2009, indicating that the current highest yield potential CIMMYT spring wheats have a co-limitation of grain growth by source and sink. This may have been due to an increase in grain sink strength with years of cultivar release with no commensurate increase in post-anthesis source capacity. The relatively low decreases in grain weight with defoliation compared to decreases in light interception by defoliation indicated that sink limitation was still likely predominating in the cultivars with co-limitation. The stem-and-leaf-sheath covering treatment decreased grain weight by nearly 10%, indicating that stem-and-leafsheath photosynthesis plays a key role in grain growth during grain filling. In addition, pre-anthesis reserve contribution to grain weight was increased by ca. 50% in response to lamina defoliation. Our results showed that increasing the post-anthesis source capacity, through increases in stem-and-leaf-sheath photosynthetic rate during grain filling and pre-anthesis reserve contribution to grain weight, is an important objective in enhancing yield potential in wheat through maintaining a source–sink balance.
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Zude-Sasse, Manuela, Ulrich Hartmond, Georg Ebert, and Peter Lüdders. "Pyridine Nucleotide Charge Reduces Photosynthesis under Short-term Oxygen Deficiency." Journal of the American Society for Horticultural Science 126, no. 6 (November 2001): 703–9. http://dx.doi.org/10.21273/jashs.126.6.703.
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Soil flooding reduces partial pressure of oxygen (pO2) in the root zone and often results in a reduction in photosynthesis and growth. In greenhouse studies, rooted stem cuttings of the mango (Mangifera indica L.) rootstock selection 13/1 were exposed to anoxia by saturating the root zone with N2 for up to 52 h. Reduced pO2 in the root zone affected the energy status of the roots and particularly enhanced the phosphorylated and nonphosphorylated pyridine nucleotide charges—the ratio of reduced Nicotinamide-adenine-dinucleotides [NAD(P)H] to total Nicotinamide-adenine-dinucleotide content [oxidized NAD(P)+ plus NAD(P)H]—that drive the redox reaction rates in cell metabolism. Also, the pyridine nucleotide charges in leaves were enhanced, while the photosynthetic rate decreased following reduction in pO2 in the root zone. During up to 4 h of reduced pO2, the ratio of internal CO2 concentration in the mesophyll to ambient CO2 concentration was unchanged. This implies a nonstomatal influence on photosynthesis. In addition, light saturation of photosystem II occurred at lower irradiance (470 μmol·m-2·s-1) resulting in reduced maximum photochemical efficiency below that of the high pO2 controls. After 28 h of reduced pO2, NAD(P) charges in the leaves returned to normal, diminishing its potential effect on net photosynthetic rate.