In the present study, we investigated the changes of photosynthesis, chlorophyll fluorescence and the content of carotenoid pigments in rice (Oryza sativa L.) seedling leaves and their responses to high light. The res...In the present study, we investigated the changes of photosynthesis, chlorophyll fluorescence and the content of carotenoid pigments in rice (Oryza sativa L.) seedling leaves and their responses to high light. The results showed that the rate of photosynthesis, the contents of individual and total carotenoids and the pool size of xanthophyll cycle decreased with age increasing of the leaf. When the leaves were exposed to high light for 2 h, the qN of mature leaf (5th leaf) increased more significantly than that of younger (6th leaf) and older leaves (3rd and 4th leaf). Comparing with the leaves before exposure to high light, the excitation pressure on PSⅡ (1- qP ) increased by 44%, 57%, 19% and 45% in the 3rd, 4th, 5th and 6th leaf under high light, respectively. The highest content of carotenoids and the greatest conversion of violaxanthin to zeaxanthin were found in the 5th leaf, and it was consistent with the 5th leaf exhibiting the strongest resistance to high light. Our results suggested that the ability of rice leaf to resist photoinhibition is related to the level of carotenoids and the ability of carotenoids biosynthesis.展开更多
[Objective] The aim was to explore the effects of water stress on leaf water and chlorophyll fluorescence parameters of sugarcane seedling,as well as to provide basis for the study on sugarcane production and evaluati...[Objective] The aim was to explore the effects of water stress on leaf water and chlorophyll fluorescence parameters of sugarcane seedling,as well as to provide basis for the study on sugarcane production and evaluation. [Method] Seven different sugarcane varieties were studied at the seedling stage under drought stress,and the changes of leaf water and chlorophyll fluorescence parameters under stress conditions were detected. [Result] leaf water potential,leaf relative water content and soil relative water content showed a certain amount of internal relationship,the sugarcane varieties that had more tolerant to drought had higher utilization rate of soil water; the correlation analysis and factor analysis suggested that the survival rate at seedling stage under drought stress,Fv/Fm,leaf water potential and relative water content could be used as drought resistance evaluation indicators. [Conclusion] As a relatively independent influencing factor,water potential had dominating effect on drought resistance,and the reliability of Fv/Fm as drought resistance evaluation indicator had been verified.展开更多
The purpose of this study was to explore influence of abiotic factors, such as high temperature, water deficiency and high solar radiation on the photomembrane of grapevine leaves. Grapevine leaves were collected from...The purpose of this study was to explore influence of abiotic factors, such as high temperature, water deficiency and high solar radiation on the photomembrane of grapevine leaves. Grapevine leaves were collected from variety Rkatsiteli （Vitis vinifera） and placed at a temperature of ＋45 ℃ and ＋55 ℃ for 5 rain, respectively. The relative volume of water in leaves was gradually reduced to 50%, and then leaves were irradiated with 6,000 pmol/m2.s of white light. Changes provoked by stressful abiotie factors were determined using rapid and delayed chlorophyll fluorescence methods. It was shown that value of variable component of chlorophyll fluorescence （Fv）, intensity of electron transport between the photosystems （ETR）, intensity of expended electrons in carboxylation （ETRn） and oxygenation （ETRp） and index of non-photochemical quenching （NPQ）, allow studying molecular mechanisms of the impact of abiotic factors and the resulting damage degree. Based on delayed and rapid fluorescence data, it was demonstrated that temperature of ＋45 ℃ adversely affects oxygen production system and CO2 assimilation mechanisms, while at ＋55 ℃, the ETR decreases. Reduction of relative water volume in leaves up to 50%-55% leads to sharp reduction in ETR and inhibition of photosynthesis. In case of irradiation of leaves with high-intensity light of 6,000 μmol/m2.s, NPQ of light falling on a leaf increases, thus protecting photosynthesis apparatus from damage.展开更多
文摘In the present study, we investigated the changes of photosynthesis, chlorophyll fluorescence and the content of carotenoid pigments in rice (Oryza sativa L.) seedling leaves and their responses to high light. The results showed that the rate of photosynthesis, the contents of individual and total carotenoids and the pool size of xanthophyll cycle decreased with age increasing of the leaf. When the leaves were exposed to high light for 2 h, the qN of mature leaf (5th leaf) increased more significantly than that of younger (6th leaf) and older leaves (3rd and 4th leaf). Comparing with the leaves before exposure to high light, the excitation pressure on PSⅡ (1- qP ) increased by 44%, 57%, 19% and 45% in the 3rd, 4th, 5th and 6th leaf under high light, respectively. The highest content of carotenoids and the greatest conversion of violaxanthin to zeaxanthin were found in the 5th leaf, and it was consistent with the 5th leaf exhibiting the strongest resistance to high light. Our results suggested that the ability of rice leaf to resist photoinhibition is related to the level of carotenoids and the ability of carotenoids biosynthesis.
基金Supported by Key Projects in the National Science &Technology Pillar Program (2007BAD30B05)Key Project of Science and Tech-nology Department of Guangxi Province of China (0782004-5)the Program for Postgraduates Research Innovattion in GX. Univer-sity (105930903049)~~
文摘[Objective] The aim was to explore the effects of water stress on leaf water and chlorophyll fluorescence parameters of sugarcane seedling,as well as to provide basis for the study on sugarcane production and evaluation. [Method] Seven different sugarcane varieties were studied at the seedling stage under drought stress,and the changes of leaf water and chlorophyll fluorescence parameters under stress conditions were detected. [Result] leaf water potential,leaf relative water content and soil relative water content showed a certain amount of internal relationship,the sugarcane varieties that had more tolerant to drought had higher utilization rate of soil water; the correlation analysis and factor analysis suggested that the survival rate at seedling stage under drought stress,Fv/Fm,leaf water potential and relative water content could be used as drought resistance evaluation indicators. [Conclusion] As a relatively independent influencing factor,water potential had dominating effect on drought resistance,and the reliability of Fv/Fm as drought resistance evaluation indicator had been verified.
文摘The purpose of this study was to explore influence of abiotic factors, such as high temperature, water deficiency and high solar radiation on the photomembrane of grapevine leaves. Grapevine leaves were collected from variety Rkatsiteli （Vitis vinifera） and placed at a temperature of ＋45 ℃ and ＋55 ℃ for 5 rain, respectively. The relative volume of water in leaves was gradually reduced to 50%, and then leaves were irradiated with 6,000 pmol/m2.s of white light. Changes provoked by stressful abiotie factors were determined using rapid and delayed chlorophyll fluorescence methods. It was shown that value of variable component of chlorophyll fluorescence （Fv）, intensity of electron transport between the photosystems （ETR）, intensity of expended electrons in carboxylation （ETRn） and oxygenation （ETRp） and index of non-photochemical quenching （NPQ）, allow studying molecular mechanisms of the impact of abiotic factors and the resulting damage degree. Based on delayed and rapid fluorescence data, it was demonstrated that temperature of ＋45 ℃ adversely affects oxygen production system and CO2 assimilation mechanisms, while at ＋55 ℃, the ETR decreases. Reduction of relative water volume in leaves up to 50%-55% leads to sharp reduction in ETR and inhibition of photosynthesis. In case of irradiation of leaves with high-intensity light of 6,000 μmol/m2.s, NPQ of light falling on a leaf increases, thus protecting photosynthesis apparatus from damage.
