The objective of the study was to determine the physiological mechanisms of plants in response to brassinolide (BR) alleviating cold water stress on rice. In this study, physiological responses of rice to exogenous BR and cold water submergence were investigated using the chilling-tolerant cultivar Kongyu 131 (KY131) and the chilling-sensitive cultivar Kenjiandao 6 (KJD6). A total of 2 mg L⁻¹ BR increased activities of superoxide dismutase (SOD) and peroxidase (POD) and the contents of soluble sugar, soluble protein, and chlorophyll, but decreased the malondialdehyde (MDA) content in KY131 and KJD6 under cold water stress. The observed decreases in SOD and POD activities and MDA content recovered quickly after plants were returned to irrigation with water at temperatures of about 23.0°C in 2014. Additionally, the contents of nitrogen (N), phosphorous (P), and potassium (K) were increased by BR treatment under cold water stress. Exposure to BR also raised the percentage of high effective leaf area and leaf area index at the heading stage. Furthermore, it promoted soluble sugar synthesis, increased the rate of dry matter accumulation, and enhanced the export and translocation rates of the stem-sheath. The yield in KJD6 was significantly (P≤0.01 and P≤0.05) higher than that of the control in 2013 and 2014, respectively. The effect of BR treatment on rice leaf SOD and POD activities, MDA, chlorophyll, P, and stem-sheath K contents were more significant in KJD6 than in KY131. In conclusion, exogenous BR effectively reduced the physiological and metabolic damage in rice due to cold stress at the booting stage, promoted functional recovery in plants that received irrigation with water at a normal temperature following cold stress, and mitigated the effects of cold water stress on yield. The two varieties exhibited differential responses to BR; the weaker cold-resistant variety was more sensitive to BR and displayed stronger responses to exogenous BR.

这项研究的目的是确定植物对油菜素内酯（BR）缓解水稻冷水胁迫的生理机制。在这项研究中，研究了水稻对耐外源BR和冷水淹没的生理反应，使用耐冷品种空育131（KY131）和对冷敏感的品种垦建道6（KJD6）。总计2 mg L ^-1BR增加了冷水胁迫下KY131和KJD6中超氧化物歧化酶（SOD）和过氧化物酶（POD）的活性以及可溶性糖，可溶性蛋白和叶绿素的含量，但降低了丙二醛（MDA）的含量。在2014年将植物重新注入温度为23.0°C的水灌溉后，观察到的SOD和POD活性下降，MDA含量迅速恢复。此外，氮（N），磷（P）和钾（K在冷水胁迫下，BR处理可增加）。在抽穗期，接触BR也提高了有效叶面积和叶面积指数的百分比。此外，它促进了可溶性糖的合成，增加了干物质的积累速率，并提高了茎鞘的出口和转运速率。P ≤0.01和P ≤0.05）比分别2013和2014中，控制高。BR处理对KJD6水稻叶片SOD和POD活性，MDA，叶绿素，P和茎鞘K含量的影响比KY131更为显着。综上所述，外源BR有效地减少了水稻在孕穗期因冷胁迫而引起的生理和代谢损伤，促进了在冷胁迫后常温灌溉的植物的功能恢复，并减轻了冷胁迫对水稻的影响。让。这两个品种对BR表现出不同的反应。抗寒性较弱的品种对BR较敏感，对外源BR的反应较强。