Diffusional conductance to CO2 is the key limitation to photosynthesis in salt‐stressed leaves of rice (Oryza sativa) |
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| Authors: | Xiaoxiao Wang Wencheng Wang Jianliang Huang Shaobing Peng Dongliang Xiong |
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| Affiliation: | National Key Laboratory of Crop Genetic Improvement, MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China |
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| Abstract: | Salinity significantly limits leaf photosynthesis but the factors causing the limitation in salt‐stressed leaves remain unclear. In the present work, photosynthetic and biochemical traits were investigated in four rice genotypes under two NaCl concentration (0 and 150 mM) to assess the stomatal, mesophyll and biochemical contributions to reduced photosynthetic rate (A) in salt‐stressed leaves. Our results indicated that salinity led to a decrease in A, leaf osmotic potential, electron transport rate and CO2 concentrations in the chloroplasts (Cc) of rice leaves. Decreased A in salt‐stressed leaves was mainly attributable to low Cc, which was determined by stomatal and mesophyll conductance. The increased stomatal limitation was mainly related to the low leaf osmotic potential caused by soil salinity. However, the increased mesophyll limitation in salt‐stressed leaves was related to both osmotic stress and ion stress. These findings highlight the importance of considering mesophyll conductance when developing salinity‐tolerant rice cultivars. |
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