Effects of high temperature stress on gas exchange and chlorophyll fluorescence parameters of Fagopyrum dibotrys
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Graphical Abstract
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Abstract
To explore the adaptation mechanisms of Fagopyrum dibotrys to high temperature stress and to evaluate the differences of heat resistance of eight F. dibotrys germplasm resources, it was measured that the characteristics of gas exchange and chlorophyll fluorescence parameters in leaves of eight germplasm resources under the high temperature (35 ℃ and 45 ℃) stress. The results showed that: There were very obvious effects of heat stress on photosynthesis and chlorophyll fluorescence parameters; With the strength of the heat stress, it was significantly decreased that the net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), water use efficiency (WUE), PSⅡ potential activity(Fv/Fo), PSⅡ maximum photochemical efficiency (Fv/Fm), PSⅡ actual photochemical quantum yield (yield) and PSⅡ photochemical fluorescence quenching (qP) in all of germplasm resources; However, it was increased that the nonphotochemical fluorescence quenching (NPQ) in leave of JQ4, JQ5, JQ7, but decreased as the strength of heat stress was increased, and steadily increased that the non-photochemical fluorescence quenching (NPQ) in leave of JQ1, JQ2, JQ3, JQ6, JQ8. The nine single indexes were changed into two comprehensive indexes by using the principal components analysis. The weight of two comprehensive indexes were 0.816 and 0.184, respectively. According to the results of subordinate function value analysis, the heat resistance capability was in the order of JQ6>JQ2>JQ3>JQ1>JQ8>JQ4>JQ5>JQ7 in eight F. dibotrys materials. Based on above, the better heat-tolerant F. dibotrys germplasm resourses could regulate the stomatal conductance, decrease the transpiration rate, increase the water use efficiency, and made excited energy dissipated as thermal dissipation to resist high temperature and protect the photosynthetic apparatus.
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