Effects of drought-heat cross stress on photosynthetic characteristics of rice seedlings
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DOI:10.7606/j.issn.1000-7601.2022.03.09
Key Words: rice seedlings  drought-heat cross stress  photosynthetic characteristics  chloroplast
Author NameAffiliation
YU Xin School of Life Science, Anhui Agricultural University, Hefei, Anhui 230036, China 
TONG Fei College of Agriculture, Anhui Agricultural University, Hefei, Anhui 230036, China 
ZHAN Ni College of Agriculture, Anhui Agricultural University, Hefei, Anhui 230036, China 
YE Ting School of Life Science, Anhui Agricultural University, Hefei, Anhui 230036, China 
WANG Qin Biotechnology Center, Anhui Agricultural University, Hefei, Anhui 230036, China 
YE Hui Biotechnology Center, Anhui Agricultural University, Hefei, Anhui 230036, China 
WU Liquan College of Agriculture, Anhui Agricultural University, Hefei, Anhui 230036, China 
LI Juan Biotechnology Center, Anhui Agricultural University, Hefei, Anhui 230036, China 
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Abstract:
      Rice ‘N22’ was used as the test variety, and the treatments included normal growth (CK) of the rice seedlings, a single heat stress (H), and drought-heat cross stress (DH) in hydroponic pot experiment, respectively. In this study, we measured chlorophyll content, photosynthetic physiological parameters and cfhlorophyll fluorescence parameters of rice seedlings leaves. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe epidermis stomatal morphology, mesophyll cell morphology and chloroplast ultra-structure. The results showed that comparing with CK, the contents of chlorophyll a and b, net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular carbon dioxide concentration (Ci) transpiration rate (Tr) and actual photochemistry quantum efficiency \[Y(Ⅱ)\] of rice seedlings were significantly reduced under H, and the decrease rates were 82.15%、66.82%、64.83%、8.23%、66.20% and 27.51%, respectively. The contents of chlorophyll a and b, Pn, Gs, Ci, Tr and Y(Ⅱ) in rice seedlings under DH were not significantly different from those under CK, but significantly higher than those under H, and DH was 4.35, 2.67, 3.20, 1.17, 3.46, and 1.23 times of H, respectively. By maintaining normal chlorophyll content, stable structure of mesophyll cell and chloroplast ultra-structure and moderate stomatal opening, the rice seedlings pretreated by drought alleviated the damage of later heat to photosynthesis ability of rice seedlings to a certain extent. Therefore, the damage of high temperature to rice seedlings growth was reduced and the heat resistance of rice seedlings was improved.