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David M Reid - One of the best experts on this subject based on the ideXlab platform.

  • Light Irradiance differentially regulates endogenous levels of cytokinins and auxin in alpine and prairie genotypes of stellaria longipes
    Physiologia Plantarum, 2008
    Co-Authors: Leonid V Kurepin, C C Chinnappa, R Neil J Emery, David M Reid
    Abstract:

    The growth patterns of plants from alpine (sun) and prairie (shade) ecotypes of Stellaria longipes in response to change in Light Irradiance was investigated and involvement of cytokinins (CKs), auxin (IAA) and abscisic acid (ABA) was studied to examine the mechanism behind phenotypic plasticity of these plants in response to Light signalling. Low Light Irradiance induced shoot growth in plants of both ecotypes, but IAA levels were higher in plants from alpine, but not prairie ecotype. Dynamics of CK profiles in response to changing photosynthetically active radiation were quite different between ecotypes and changes were more pronounced in the plants of alpine ecotype, where opposite patterns in CK accumulation between low and normal Light Irradiances were observed. The plants of both ecotypes showed similar trends in ABA levels under low Light Irradiance. Thus, the highly plastic plants of prairie ecotype may have evolved mechanisms to control the growth in response to reduced Light Irradiance without major alterations in the levels of CKs or IAA. These results demonstrate that within species, plants from open habitats show less growth response to reduced Light Irradiance than plants from shaded habitats.

  • uncoupling Light quality from Light Irradiance effects in helianthus annuus shoots putative roles for plant hormones in leaf and internode growth
    Journal of Experimental Botany, 2007
    Co-Authors: Leonid V Kurepin, Richard P. Pharis, R Neil J Emery, David M Reid
    Abstract:

    An attempt has been made to uncouple the effects of the two primary components of shade Light, a reduced red to far-red (R/FR) ratio and low photosynthetically active radiation (PAR), on the elongation of the youngest internode of sunflower (Helianthus annuus) seedlings. Maximal internode growth (length and biomass) was induced by a shade Light having a reduced R/FR ratio (0.85) under the low PAR of 157 mmol m 22 s 21 . Reducing the R/FR ratio under normal PAR (421 mmol m 22 s 21 ) gave similar growth trends, albeit with a reduced magnitude of the response. Leaf area growth showed a rather different pattern, with maximal growth occurring at the higher (normal) PAR of 421 mmol m 22 s 21 ), but with variable effects being seen with changes in Light quality. Reducing the R/FR ratio (by enrichment with FR) gave significant increases in gibberellin A1 (GA1) and indole-3-acetic acid (IAA) contents in both internodes and leaves. By contrast, a lower PAR Irradiance had no significant effect on GA1 and IAA levels in internodes or leaves, but did increase the levels of other GAs, including two precursors of GA1. Interestingly, both leaf and internode hormone content (GAs, IAA) are positively and significantly correlated with growth of the internode, as are leaf levels of abscisic acid (ABA). However, changes in these three hormones bear little relationship to leaf growth. By implication, then, the leaf may be the major source of GAs and IAA, at least, for the rapidly elongating internode. Several other hormones were also assessed in leaves for plants grown under varying R/FR ratios and PARs. Leaf ethylene production was not influenced by changes in R/FR ratio, but was significantly reduced under the normal (higher) PAR, the Irradiance treatment which increased leaf growth. Levels of the growth-active free base and riboside cytokinins were significantly increased in leaves under a reduced R/FR ratio, but only at the higher (normal) PAR Irradiance; other Light quality treatments evoked no significant changes. Taken in toto, these results indicate that both components of shade Light can influence the levels of a wide range of endogenous hormones in internodes and leaves while evoking increased internode elongation and biomass accumulation. However, it is Light quality changes (FR enrichment) which are most closely tied to increased hormone content, and especially with increased GA and IAA levels. Finally, the increases seen in internode and leaf GA content with a reduced R/FR ratio are consistent with FR enrichment inducing an overall increase in sunflower seedling GA biosynthesis.

  • interaction of red to far red Light ratio and ethylene in regulating stem elongation of helianthus annuus
    Plant Growth Regulation, 2007
    Co-Authors: Leonid V Kurepin, Linda J Walton, David M Reid
    Abstract:

    Sunflower (Helianthus annuus L.) stems showed increased elongation under two types of vegetative shade: canopy shade (low red to far red [R/FR] ratio) and neighbouring proximity shade (FR enrichment). Hypocotyls also elongated more under narrow-band FR Light than under narrow-band R Light. Ethylene levels were determined in actively elongating 7-day-old hypocotyls and 17-day-old internodes under three R/FR ratios. Ethylene levels were lower in both sunflower hypocotyls and internodes when the R/FR ratio was reduced. Both FR enrichment of normal R/FR ratio and narrow-band FR Light with very low Light Irradiance resulted in reduction in ethylene levels in 7-day-old hypocotyls. Further, in application experiments, sunflower stems grown under low R/FR ratio were more sensitive to ethephon and less sensitive to aminoethoxyvinylglycine (AVG) than stems grown under high R/FR ratio. Low R/FR ratio appears to initiate reduction in ethylene levels in sunflower seedlings, allowing maximum stem elongation. These results, and findings of other authors, suggest that various plant species may have developed different ways of regulating stem elongation and ethylene levels in response to low R/FR ratio.

  • involvement of gibberellins in the stem elongation of sun and shade ecotypes of stellaria longipes that is induced by low Light Irradiance
    Plant Cell and Environment, 2006
    Co-Authors: Leonid V Kurepin, Richard P. Pharis, David M Reid, C C Chinnappa
    Abstract:

    ABSTRACTPlants from two ecotypes of Stellaria longipes, alpine (anopen, sunny habitat) and prairie (where adjacent plantsprovide a shaded habitat), were grown under normal andreduced levels of photosynthetically active radiation(PAR). Growth under low PAR is significantly promotedin both ecotypes. When quantified by the stable isotopedilution method, endogenous gibberellins (GAs) (GA 1,GA 8, GA 20, GA 19) were significantly elevated under lowPAR in both ‘sun’ and ‘shade’ ecotypes, as was GA 53 in theshade ecotype. Changes in endogenous GA 1 levels weresignificantly correlated with stem growth during a 28 dgrowth cycle and with relative growth rate (RGR) forheight under low PAR for both ecotypes. Interestingly,under low Irradiance PAR, changes (both increases anddecreases) in GA 8, the 2b-hydroxylated ‘inactive’ cataboliteof GA 1, closely parallel bidaily stem growth changes forboth ecotypes. Because the significantly greater stem elon-gation of both ecotypes in response to low Irradiance PARis associated with significant increases in the endogenouslevels of five GAs (GA 53, GA 19, GA 1, GA 8) in the early 13-hydroxylation GA biosynthesis pathway (measured at days7, 14 and 21), we conclude that the low Irradiance PAR hasvery likely induced an overall increase in GA biosynthesis.Key-words: ecotype differentiation; PAR; shade plant; sunplant.

  • growth and ethylene evolution by shade and sun ecotypes of stellaria longipes in response to varied Light quality and Irradiance
    Plant Cell and Environment, 2006
    Co-Authors: Leonid V Kurepin, Richard P. Pharis, David M Reid, Linda J Walton, C C Chinnappa
    Abstract:

    Plants growing in the shade receive both low Light Irradiance and Light enriched in far red (FR) (i.e. Light with a low red (R) to FR ratio). In an attempt to uncouple the R/FR ratio effects from Light Irradiance effects, we utilized Stellaria longipes because this species has two distinct natural population ecotypes, alpine (dwarf) and prairie (tall). The alpine population occupies the open, sun habitat. By contrast, the prairie population grows in the shade of other plants. Both ‘sun’ and ‘shade’ ecotypes responded with increased stem elongation responses under low Irradiance, relative to growth under ‘normal’ Irradiance, and this increased growth was proportionally similar. However, only the shade ecotype had increased shoot elongation in response to a low R/FR ratio. By contrast, the sun ecotype showed increased stem elongation in response to increasing R/FR ratio. Varying the R/FR ratios had no significant effect on ethylene evolution in either sun or shade ecotype. Under low Irradiance, only the sun ecotype showed a significantly changed (decreased) ethylene evolution. We conclude that R/FR ratio and Irradiance both regulate growth, and that Irradiance can also influence ethylene evolution of the sun ecotype. By contrast, R/FR ratio and Irradiance, while having profound influences on growth of the shade ecotype, do not appear to regulate these growth changes via effects on ethylene production.

Leonid V Kurepin - One of the best experts on this subject based on the ideXlab platform.

  • Light Irradiance differentially regulates endogenous levels of cytokinins and auxin in alpine and prairie genotypes of stellaria longipes
    Physiologia Plantarum, 2008
    Co-Authors: Leonid V Kurepin, C C Chinnappa, R Neil J Emery, David M Reid
    Abstract:

    The growth patterns of plants from alpine (sun) and prairie (shade) ecotypes of Stellaria longipes in response to change in Light Irradiance was investigated and involvement of cytokinins (CKs), auxin (IAA) and abscisic acid (ABA) was studied to examine the mechanism behind phenotypic plasticity of these plants in response to Light signalling. Low Light Irradiance induced shoot growth in plants of both ecotypes, but IAA levels were higher in plants from alpine, but not prairie ecotype. Dynamics of CK profiles in response to changing photosynthetically active radiation were quite different between ecotypes and changes were more pronounced in the plants of alpine ecotype, where opposite patterns in CK accumulation between low and normal Light Irradiances were observed. The plants of both ecotypes showed similar trends in ABA levels under low Light Irradiance. Thus, the highly plastic plants of prairie ecotype may have evolved mechanisms to control the growth in response to reduced Light Irradiance without major alterations in the levels of CKs or IAA. These results demonstrate that within species, plants from open habitats show less growth response to reduced Light Irradiance than plants from shaded habitats.

  • uncoupling Light quality from Light Irradiance effects in helianthus annuus shoots putative roles for plant hormones in leaf and internode growth
    Journal of Experimental Botany, 2007
    Co-Authors: Leonid V Kurepin, Richard P. Pharis, R Neil J Emery, David M Reid
    Abstract:

    An attempt has been made to uncouple the effects of the two primary components of shade Light, a reduced red to far-red (R/FR) ratio and low photosynthetically active radiation (PAR), on the elongation of the youngest internode of sunflower (Helianthus annuus) seedlings. Maximal internode growth (length and biomass) was induced by a shade Light having a reduced R/FR ratio (0.85) under the low PAR of 157 mmol m 22 s 21 . Reducing the R/FR ratio under normal PAR (421 mmol m 22 s 21 ) gave similar growth trends, albeit with a reduced magnitude of the response. Leaf area growth showed a rather different pattern, with maximal growth occurring at the higher (normal) PAR of 421 mmol m 22 s 21 ), but with variable effects being seen with changes in Light quality. Reducing the R/FR ratio (by enrichment with FR) gave significant increases in gibberellin A1 (GA1) and indole-3-acetic acid (IAA) contents in both internodes and leaves. By contrast, a lower PAR Irradiance had no significant effect on GA1 and IAA levels in internodes or leaves, but did increase the levels of other GAs, including two precursors of GA1. Interestingly, both leaf and internode hormone content (GAs, IAA) are positively and significantly correlated with growth of the internode, as are leaf levels of abscisic acid (ABA). However, changes in these three hormones bear little relationship to leaf growth. By implication, then, the leaf may be the major source of GAs and IAA, at least, for the rapidly elongating internode. Several other hormones were also assessed in leaves for plants grown under varying R/FR ratios and PARs. Leaf ethylene production was not influenced by changes in R/FR ratio, but was significantly reduced under the normal (higher) PAR, the Irradiance treatment which increased leaf growth. Levels of the growth-active free base and riboside cytokinins were significantly increased in leaves under a reduced R/FR ratio, but only at the higher (normal) PAR Irradiance; other Light quality treatments evoked no significant changes. Taken in toto, these results indicate that both components of shade Light can influence the levels of a wide range of endogenous hormones in internodes and leaves while evoking increased internode elongation and biomass accumulation. However, it is Light quality changes (FR enrichment) which are most closely tied to increased hormone content, and especially with increased GA and IAA levels. Finally, the increases seen in internode and leaf GA content with a reduced R/FR ratio are consistent with FR enrichment inducing an overall increase in sunflower seedling GA biosynthesis.

  • interaction of red to far red Light ratio and ethylene in regulating stem elongation of helianthus annuus
    Plant Growth Regulation, 2007
    Co-Authors: Leonid V Kurepin, Linda J Walton, David M Reid
    Abstract:

    Sunflower (Helianthus annuus L.) stems showed increased elongation under two types of vegetative shade: canopy shade (low red to far red [R/FR] ratio) and neighbouring proximity shade (FR enrichment). Hypocotyls also elongated more under narrow-band FR Light than under narrow-band R Light. Ethylene levels were determined in actively elongating 7-day-old hypocotyls and 17-day-old internodes under three R/FR ratios. Ethylene levels were lower in both sunflower hypocotyls and internodes when the R/FR ratio was reduced. Both FR enrichment of normal R/FR ratio and narrow-band FR Light with very low Light Irradiance resulted in reduction in ethylene levels in 7-day-old hypocotyls. Further, in application experiments, sunflower stems grown under low R/FR ratio were more sensitive to ethephon and less sensitive to aminoethoxyvinylglycine (AVG) than stems grown under high R/FR ratio. Low R/FR ratio appears to initiate reduction in ethylene levels in sunflower seedlings, allowing maximum stem elongation. These results, and findings of other authors, suggest that various plant species may have developed different ways of regulating stem elongation and ethylene levels in response to low R/FR ratio.

  • involvement of gibberellins in the stem elongation of sun and shade ecotypes of stellaria longipes that is induced by low Light Irradiance
    Plant Cell and Environment, 2006
    Co-Authors: Leonid V Kurepin, Richard P. Pharis, David M Reid, C C Chinnappa
    Abstract:

    ABSTRACTPlants from two ecotypes of Stellaria longipes, alpine (anopen, sunny habitat) and prairie (where adjacent plantsprovide a shaded habitat), were grown under normal andreduced levels of photosynthetically active radiation(PAR). Growth under low PAR is significantly promotedin both ecotypes. When quantified by the stable isotopedilution method, endogenous gibberellins (GAs) (GA 1,GA 8, GA 20, GA 19) were significantly elevated under lowPAR in both ‘sun’ and ‘shade’ ecotypes, as was GA 53 in theshade ecotype. Changes in endogenous GA 1 levels weresignificantly correlated with stem growth during a 28 dgrowth cycle and with relative growth rate (RGR) forheight under low PAR for both ecotypes. Interestingly,under low Irradiance PAR, changes (both increases anddecreases) in GA 8, the 2b-hydroxylated ‘inactive’ cataboliteof GA 1, closely parallel bidaily stem growth changes forboth ecotypes. Because the significantly greater stem elon-gation of both ecotypes in response to low Irradiance PARis associated with significant increases in the endogenouslevels of five GAs (GA 53, GA 19, GA 1, GA 8) in the early 13-hydroxylation GA biosynthesis pathway (measured at days7, 14 and 21), we conclude that the low Irradiance PAR hasvery likely induced an overall increase in GA biosynthesis.Key-words: ecotype differentiation; PAR; shade plant; sunplant.

  • growth and ethylene evolution by shade and sun ecotypes of stellaria longipes in response to varied Light quality and Irradiance
    Plant Cell and Environment, 2006
    Co-Authors: Leonid V Kurepin, Richard P. Pharis, David M Reid, Linda J Walton, C C Chinnappa
    Abstract:

    Plants growing in the shade receive both low Light Irradiance and Light enriched in far red (FR) (i.e. Light with a low red (R) to FR ratio). In an attempt to uncouple the R/FR ratio effects from Light Irradiance effects, we utilized Stellaria longipes because this species has two distinct natural population ecotypes, alpine (dwarf) and prairie (tall). The alpine population occupies the open, sun habitat. By contrast, the prairie population grows in the shade of other plants. Both ‘sun’ and ‘shade’ ecotypes responded with increased stem elongation responses under low Irradiance, relative to growth under ‘normal’ Irradiance, and this increased growth was proportionally similar. However, only the shade ecotype had increased shoot elongation in response to a low R/FR ratio. By contrast, the sun ecotype showed increased stem elongation in response to increasing R/FR ratio. Varying the R/FR ratios had no significant effect on ethylene evolution in either sun or shade ecotype. Under low Irradiance, only the sun ecotype showed a significantly changed (decreased) ethylene evolution. We conclude that R/FR ratio and Irradiance both regulate growth, and that Irradiance can also influence ethylene evolution of the sun ecotype. By contrast, R/FR ratio and Irradiance, while having profound influences on growth of the shade ecotype, do not appear to regulate these growth changes via effects on ethylene production.

M P Fuller - One of the best experts on this subject based on the ideXlab platform.

  • effect of photosynthetic photon flux density on growth photosynthetic competence and antioxidant enzymes activity during ex vitro acclimatization of dieffenbachia cultivars
    Plant Growth Regulation, 2016
    Co-Authors: Mohammed Elsayed Elmahrouk, Yaser Hassan Dewir, Hosakatte Niranjana Murthy, Hail Z Rihan, Hanady S A Alshmgani, M P Fuller
    Abstract:

    The effects of 35, 70 and 100 µmol m−2 s−1 photosynthetic photon flux density (PPFD) were investigated on ex vitro acclimatization of micropropagated Dieffenbachia plants. Various growth characteristics, photosynthetic parameters and activities of antioxidant enzymes and dehydrins (DHN) were investigated. Fresh and dry plant biomass, plant height and root length were highest under the highest PPFD (100 µmol m−2 s−1), but this treatment was responsible for a reduction in the number of leaves. Chlorophyll and carotenoid contents and net photosynthesis were also optimal in plants grown under the highest Irradiance. Stomatal resistance, transpiration rate and F v/F m values decreased with the incremental Light Irradiance. Activities of the antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase were higher in the plants treated with 70 and 100 µmol m−2 s−1 PPFD. Accumulation of 55 kDa, 40 and 22 kDa DHN was observed in all Light treatments. These results depict that lower PPFD (35 µmol m−2 s−1) was suitable for acclimatization of Dieffenbachia plants. High PPFD (>70 µmol m−2 s−1) induced accumulation of antioxidants and accumulation of DHN in the plants which reveals enhanced stress levels.

  • Effect of photosynthetic photon flux density on growth, photosynthetic competence and antioxidant enzymes activity during ex vitro acclimatization of Dieffenbachia cultivars
    Plant Growth Regulation, 2015
    Co-Authors: Mohammed Elsayed El-mahrouk, Yaser Hassan Dewir, Hosakatte Niranjana Murthy, Hail Z Rihan, Hanady S.a. Al-shmgani, M P Fuller
    Abstract:

    © 2015, Springer Science+Business Media Dordrecht. The effects of 35, 70 and 100 µmol m −2  s −1 photosynthetic photon flux density (PPFD) were investigated on ex vitro acclimatization of micropropagated Dieffenbachia plants. Various growth characteristics, photosynthetic parameters and activities of antioxidant enzymes and dehydrins (DHN) were investigated. Fresh and dry plant biomass, plant height and root length were highest under the highest PPFD (100 µmol m −2  s −1 ), but this treatment was responsible for a reduction in the number of leaves. Chlorophyll and carotenoid contents and net photosynthesis were also optimal in plants grown under the highest Irradiance. Stomatal resistance, transpiration rate and F v /F m values decreased with the incremental Light Irradiance. Activities of the antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase were higher in the plants treated with 70 and 100 µmol m −2  s −1 PPFD. Accumulation of 55 kDa, 40 and 22 kDa DHN was observed in all Light treatments. These results depict that lower PPFD (35 µmol m −2  s −1 ) was suitable for acclimatization of Dieffenbachia plants. High PPFD ( > 70 µmol m −2  s −1 ) induced accumulation of antioxidants and accumulation of DHN in the plants which reveals enhanced stress levels

  • photosynthetic and biochemical characterization of in vitro derived african violet saintpaulia ionantha h wendl plants to ex vitro conditions
    Journal of Plant Interactions, 2015
    Co-Authors: Yaser Hassan Dewir, Mohammed Elsayed Elmahrouk, Hail Z Rihan, Hanady S A Alshmgani, Jaime Teixeira A Da Silva, M P Fuller
    Abstract:

    African violet (Saintpaulia ionantha H. Wendl) is one of the most easily and commonly tissue-cultured ornamental plants. Despite this, there are limited reports on photosynthetic capacity and its impact on the plant quality during acclimatization. Various growth, photosynthetic and biochemical parameters and activities of antioxidant enzymes and dehydrins of micropropagated plants were assessed under three Light intensities (35, 70, and 100 µmol m−2 s−1 photosynthetic photon flux density – PPFD). Fresh and dry plant biomass, plant height, and leaf area were optimal with high Irradiance (70–100 µmol m−2 s−1 PPFD). Chlorophyll and carotenoid contents and net photosynthesis were optimal in plants grown under 70 µmol m−2 s−1 PPFD. Stomatal resistance, malondialdehyde content, and Fv/Fm values were highest at low Light Irradiance (35 µmol m−2 s−1 PPFD). The activities of three antioxidant enzymes, superoxide dismutase, catalase, and glutathione peroxidase, increased as Light Irradiance increased, signaling tha...

Yaser Hassan Dewir - One of the best experts on this subject based on the ideXlab platform.

  • effect of photosynthetic photon flux density on growth photosynthetic competence and antioxidant enzymes activity during ex vitro acclimatization of dieffenbachia cultivars
    Plant Growth Regulation, 2016
    Co-Authors: Mohammed Elsayed Elmahrouk, Yaser Hassan Dewir, Hosakatte Niranjana Murthy, Hail Z Rihan, Hanady S A Alshmgani, M P Fuller
    Abstract:

    The effects of 35, 70 and 100 µmol m−2 s−1 photosynthetic photon flux density (PPFD) were investigated on ex vitro acclimatization of micropropagated Dieffenbachia plants. Various growth characteristics, photosynthetic parameters and activities of antioxidant enzymes and dehydrins (DHN) were investigated. Fresh and dry plant biomass, plant height and root length were highest under the highest PPFD (100 µmol m−2 s−1), but this treatment was responsible for a reduction in the number of leaves. Chlorophyll and carotenoid contents and net photosynthesis were also optimal in plants grown under the highest Irradiance. Stomatal resistance, transpiration rate and F v/F m values decreased with the incremental Light Irradiance. Activities of the antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase were higher in the plants treated with 70 and 100 µmol m−2 s−1 PPFD. Accumulation of 55 kDa, 40 and 22 kDa DHN was observed in all Light treatments. These results depict that lower PPFD (35 µmol m−2 s−1) was suitable for acclimatization of Dieffenbachia plants. High PPFD (>70 µmol m−2 s−1) induced accumulation of antioxidants and accumulation of DHN in the plants which reveals enhanced stress levels.

  • Effect of photosynthetic photon flux density on growth, photosynthetic competence and antioxidant enzymes activity during ex vitro acclimatization of Dieffenbachia cultivars
    Plant Growth Regulation, 2015
    Co-Authors: Mohammed Elsayed El-mahrouk, Yaser Hassan Dewir, Hosakatte Niranjana Murthy, Hail Z Rihan, Hanady S.a. Al-shmgani, M P Fuller
    Abstract:

    © 2015, Springer Science+Business Media Dordrecht. The effects of 35, 70 and 100 µmol m −2  s −1 photosynthetic photon flux density (PPFD) were investigated on ex vitro acclimatization of micropropagated Dieffenbachia plants. Various growth characteristics, photosynthetic parameters and activities of antioxidant enzymes and dehydrins (DHN) were investigated. Fresh and dry plant biomass, plant height and root length were highest under the highest PPFD (100 µmol m −2  s −1 ), but this treatment was responsible for a reduction in the number of leaves. Chlorophyll and carotenoid contents and net photosynthesis were also optimal in plants grown under the highest Irradiance. Stomatal resistance, transpiration rate and F v /F m values decreased with the incremental Light Irradiance. Activities of the antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase were higher in the plants treated with 70 and 100 µmol m −2  s −1 PPFD. Accumulation of 55 kDa, 40 and 22 kDa DHN was observed in all Light treatments. These results depict that lower PPFD (35 µmol m −2  s −1 ) was suitable for acclimatization of Dieffenbachia plants. High PPFD ( > 70 µmol m −2  s −1 ) induced accumulation of antioxidants and accumulation of DHN in the plants which reveals enhanced stress levels

  • photosynthetic and biochemical characterization of in vitro derived african violet saintpaulia ionantha h wendl plants to ex vitro conditions
    Journal of Plant Interactions, 2015
    Co-Authors: Yaser Hassan Dewir, Mohammed Elsayed Elmahrouk, Hail Z Rihan, Hanady S A Alshmgani, Jaime Teixeira A Da Silva, M P Fuller
    Abstract:

    African violet (Saintpaulia ionantha H. Wendl) is one of the most easily and commonly tissue-cultured ornamental plants. Despite this, there are limited reports on photosynthetic capacity and its impact on the plant quality during acclimatization. Various growth, photosynthetic and biochemical parameters and activities of antioxidant enzymes and dehydrins of micropropagated plants were assessed under three Light intensities (35, 70, and 100 µmol m−2 s−1 photosynthetic photon flux density – PPFD). Fresh and dry plant biomass, plant height, and leaf area were optimal with high Irradiance (70–100 µmol m−2 s−1 PPFD). Chlorophyll and carotenoid contents and net photosynthesis were optimal in plants grown under 70 µmol m−2 s−1 PPFD. Stomatal resistance, malondialdehyde content, and Fv/Fm values were highest at low Light Irradiance (35 µmol m−2 s−1 PPFD). The activities of three antioxidant enzymes, superoxide dismutase, catalase, and glutathione peroxidase, increased as Light Irradiance increased, signaling tha...

Deliang Wang - One of the best experts on this subject based on the ideXlab platform.

  • comparative study of gaas and cdte solar cell performance under low intensity Light Irradiance
    Solar Energy, 2017
    Co-Authors: Kai Shen, Ruilong Yang, Yongming Zhao, Rongxin Wang, Jianrong Dong, Deliang Wang
    Abstract:

    Abstract Comparative study of GaAs and CdTe solar cell under low-intensity Light Irradiance was carried out to study the cell device performance in response to the changed Light Irradiance intensity. For highly efficient GaAs solar cell, the series Rs and the shunt Rp resistance were found to be low/high enough to have almost undetectable negative effect on the cell device performance at low-intensity Light Irradiance. The robust diode parameters guaranteed good cell performance at low-intensity Light Irradiance. An ideal logarithmic function was established to describe the variation of cell efficiency with Light Irradiance intensity for GaAs solar cell. For CdTe polycrystalline solar cell, the relatively large series resistance Rs and small shunt resistance Rp, compared to that of the GaAs solar cell, significantly decreased the cell fill factor. With increased Light illumination intensity, both the diode ideality factor A and the reverse saturation current density J0 were increased due to the high density of interface states at the CdS/CdTe junction. The comparative study and conclusions drawn in this work provide device fabrication improvement direction for the CdTe solar cell.

  • cdte solar cell performance under low intensity Light Irradiance
    Solar Energy Materials and Solar Cells, 2014
    Co-Authors: Kai Shen, Ruilong Yang, Dezhao Wang, Yi Deng, Mingjer Jeng, Deliang Wang
    Abstract:

    Abstract Study of the device characteristics of a CdTe solar cell under weak Light Irradiance ( E irra ) is important both for the understanding of the fundamental device physics and for the commercial application, where E irra with intensity much less than one sun is often encountered for an outdoor solar cell module. In this study, CdTe solar cell performance under E irra as low as 0.015 sun was studied. Both the fill factor (FF) and the open-circuit voltage ( V oc ) were found to be critically affected by the shunt resistance at low E irra . The current shunting depends critically on the physical location of the shunting paths in the CdTe absorber layer. Space-charge limited current (SCLC) was identified to be an important contribution to the shunting current in thin film CdTe solar cell. At an E irra as low as 0.015 Sun, CdTe solar cell with a high shunt resistance maintained an efficiency of ~70 to 80% of the value tested at the standard AM1.5 E irra . The experimental results showed that polycrystalline CdTe thin film solar cell is a good photovoltaic device for electric power generation at low E irra . This study provides constructive guidelines for the future design and fabrication of CdTe solar cells.