Abstract:

To screen out the compound regulators that can simultaneously alleviate the dual stress of high temperature and arsenic during the rice tillering stage, three common high temperature alleviation agents (potassium dihydrogen phosphate, sucrose, and methyl jasmonic acid) and three arsenic-blocking agents (water-soluble silicon fertilizer, potassium sulfate, and organic selenium fertilizer) were selected, and each of them was mixed in pairs to form compound regulators. Through pot experiments, the compound regulators were sprayed on the rice leaves before or after the dual stress of 37 ℃ and 5 μmol∙L⁻¹ arsenic. Subsequently, the relative content of chlorophyll (SPAD), net photosynthetic rate, antioxidant enzyme activity, malondialdehyde content and content of arsenic, silicon and selenium in the rice leaves were measured. The results showed that different regulators and spraying patterns significantly affected the physiology and arsenic uptake of rice. Overall, spraying after the stress approved more effective than pre-stress application. All regulators could increase the SPAD value of rice leaves, and the treatments containing potassium dihydrogen phosphate had higher SPAD values. The treatments containing sucrose or organic selenium fertilizer enhanced the activities of superoxide dismutase (SOD) and peroxidase (POD), among which the treatments containing potassium dihydrogen phosphate and organic selenium fertilizer had higher SOD and POD activities. The treatments containing methyl jasmonic acid significantly enhanced the catalase (CAT) activity and reduced the malondialdehyde (MDA) content. Among them, the MDA content for the treatment of methyl jasmonic acid and water-soluble silicon fertilizer was the lowest, which decreased significantly by 54.8% and 68.1% compared with the control before and after the stress, respectively (p<0.05). The compound regulators reduced the arsenic content in the roots and stem-leaves of rice, among which the treatments containing organic selenium fertilizer and methyl jasmonic acid still performed the best. In general, if the compound regulators such as “potassium dihydrogen phosphate-organic selenium fertilizer” or “methyl jasmonic acid-organic selenium fertilizer” are sprayed on the rice leaves after the dual stress of high temperature and arsenic during the rice tillering stage, it can effectively protect the photosynthetic system of rice leaves, activate the antioxidant defense system, and reduce arsenic accumulation, providing a feasible technical path for the safe production of rice in arsenic-contaminated areas under the background of climate warming.

Key words: rice, foliar regulators, high temperature stress, arsenic contamination, antioxidant defense system

摘要：

为筛选出能同时缓解水稻分蘖期高温与砷双重胁迫的复合调节剂，分别选取3种常用高温缓解剂（磷酸二氢钾、蔗糖、茉莉酸甲酯）和砷阻控剂（水溶性硅肥、硫酸钾、有机硒肥），两两混合配成复合调节剂。通过盆栽试验，分别在37 ℃和5 μmol∙L⁻¹砷双重胁迫前或胁迫后，对水稻叶片喷施复合调节剂，测定水稻叶片叶绿素相对含量（SPAD）、净光合速率、抗氧化酶活性、丙二醛含量与水稻砷、硅、硒含量等指标。结果表明，不同调节剂和喷施方式显著影响水稻生理及砷吸收，总体上，胁迫后喷施优于胁迫前。所有调节剂均可提高水稻叶片的SPAD值，而含磷酸二氢钾的处理SPAD值均处于较高水平。含蔗糖或有机硒肥的处理增强了超氧化物歧化酶（SOD）和过氧化物酶（POD）活性，其中磷酸二氢钾-有机硒肥处理的SOD和POD活性较大。含茉莉酸甲酯的处理则显著增强了过氧化氢酶（CAT）活性，降低了丙二醛（MDA）含量，其中茉莉酸甲酯-水溶性硅肥处理的MDA含量最低，分别与前后喷施对照相比显著下降54.8%和68.1%（p<0.05）。复合调节剂均减少水稻根和茎叶的砷含量，其中含有机硒肥和茉莉酸甲酯的处理依旧表现最佳。总体而言，水稻分蘖期若在高温-砷复合胁迫后喷施“磷酸二氢钾-有机硒肥”或“茉莉酸甲酯-有机硒肥”等复合调节剂，可有效保护水稻叶片光合系统、激活抗氧化防御系统、减少砷积累，为气候变暖背景下砷污染区水稻安全生产提供可行的技术路径。

关键词: 水稻, 叶面调节剂, 高温胁迫, 砷污染, 抗氧化系统