Agricultural College, Anhui Agricultural University, Hefei, Anhui, China.
Pujiwei Modern Agriculture Group, Tongling, Anhui, China.
Physiol Plant. 2024 Sep-Oct;176(5):e14518. doi: 10.1111/ppl.14518.
Water-saving and drought-resistant rice (WDR) coupled with alternate wetting and drying irrigation (AWDI) possesses a high photosynthetic potential due to higher mesophyll conductance (g) under drought conditions. However, the physiological and structural contributions to the g of leaves and their mechanisms in WDR under AWDI are still unclear. In this study, WDR (Hanyou 73) and drought-sensitive rice (Huiliangyou 898) were selected as materials. Three irrigation patterns were established from transplanting to the heading stage, including conventional flooding irrigation (W1), moderate AWDI (W2), and severe AWDI (W3). A severe drought with a soil water potential of -50 kPa was applied for a week at the heading stage across all treatments and cultivars. The results revealed that severe drought reduced gas exchange parameters and g but enhanced antioxidant enzyme activities and malondialdehyde content in the three treatments and both cultivars. The maximal photosynthetic rate (A) of HY73 in the W2 treatment was greater than that in the other combinations of cultivars and irrigation patterns. The contribution of leaf structure (54%) to g (g-S, structural g) was higher than that of leaf physiology (46%) to g (g-P, physiological g) in the W2 treatment of Hanyou 73. Additionally, g-S was significantly and linearly positively correlated with g under severe drought. Moreover, both the initial and apparent quantum efficiencies were significantly and positively with g in rice plants (p < 0.05). These results suggest that the improvements in photosynthesis and yield in the WDR combined with moderate AWDI can mainly be attributed to the enhancement of g-S under severe drought conditions. Quantum efficiency may be a potential factor in regulating photosynthesis by cooperating with the g of rice plants under severe drought conditions.
节水抗旱稻（WDR）与交替湿润和干燥灌溉（AWDI）相结合，由于在干旱条件下具有较高的叶肉导度（g），因此具有较高的光合潜力。然而，在 AWDI 下，WDR 叶片的 g 的生理和结构贡献及其机制尚不清楚。本研究以节水抗旱稻（Hanyou 73）和干旱敏感型水稻（Huiliangyou 898）为材料。在移栽到抽穗期设置了三种灌溉模式，包括常规淹水灌溉（W1）、适度 AWDI（W2）和重度 AWDI（W3）。在所有处理和品种中，在抽穗期都进行了为期一周的严重干旱处理，土壤水势为-50kPa。结果表明，严重干旱降低了三种处理和两个品种的气体交换参数和 g，但提高了抗氧化酶活性和丙二醛含量。W2 处理下 HY73 的最大光合速率（A）大于其他品种和灌溉模式的组合。W2 处理下 Hanyou 73 的叶片结构（54%）对 g（g-S，结构 g）的贡献高于叶片生理（46%）对 g（g-P，生理 g）的贡献。此外，g-S 在严重干旱下与 g 呈显著线性正相关。此外，初始和表观量子效率与水稻植株中的 g 呈显著正相关（p<0.05）。这些结果表明，节水抗旱稻与适度 AWDI 相结合，在严重干旱条件下提高光合作用和产量主要归因于 g-S 的增强。在严重干旱条件下，量子效率可能是通过与水稻植株的 g 合作调节光合作用的一个潜在因素。
