氮素粒肥缓解水稻灌浆期高温胁迫的生理机制研究

[目的] 通过探究氮素粒肥缓解水稻灌浆期高温胁迫响应生理机制，为栽培措施缓解水稻高温危害提供理论基础。[方法] 以‘武运粳24号’和‘宁粳3号’为材料，进行盆栽试验，于开花期进行低氮（每盆0 g纯氮）、中氮（每盆0.8 g纯氮）、高氮（每盆1.6 g纯氮）3种施氮水平处理，6 d后移入温室进行高温处理。测定了水稻叶温及穗温，净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr），SOD、POD、NR、GS活性，MDA、可溶性蛋白及氨基酸含量等。[结果] 施用氮素粒肥显著降低了水稻的叶温和穗温，减少了高温下MDA的积累，促进水稻叶片的光合作用，提高抗氧化酶活性，增强了水稻植株氮代谢，增加硝酸还原酶、谷氨酰胺合成酶活性及氨基酸的含量。灌浆期高温降低了水稻结实率和千粒质量，氮素粒肥的施用显著缓解了高温对千粒质量和稻谷产量的影响。2个品种产量在各处理间存在显著差异，产量以低氮高温处理最低，高氮常温处理最高。‘宁粳3号’对高温胁迫更为敏感，减产幅度更大。高温胁迫初期水稻叶片内氨基酸含量显著提高，但随着胁迫时间的延长，叶片内氨基酸含量呈下降态势。氮素粒肥的施用既显著提高高温胁迫下水稻灌浆早期叶片中氨基酸的含量，同时也能持续维系水稻叶片有较高的氨基酸含量，从而提高了水稻抗逆性。[结论] 氮素粒肥的施用能显著提高植物体内氮代谢水平与抗氧化酶活性，并增加叶片氨基酸含量，减少高温逆境条件下水稻产量损失。
[Objectives] The paper aims to investigate the effect of nitrogen granular fertilizer on rice under high temperature stress and its physiological mechanism of stress response,so as to provide cultivation guidance for avoiding rice heat damages. [Methods] Two major cultivars,‘Wuyunjing 24’ and ‘Ningjing 3’,were used in this study and,under three nitrogen fertilizer levels,low nitrogen level(LN,0 g nitrogen per pot),medium nitrogen level(MN,0.8 g nitrogen per pot),and high nitrogen level(HN,1.6 g nitrogen per pot) were established. The nitrogen treatment was taken in flowering stage of rice,and after 6 days we moved rice into greenhouse. Temperature of rice panicle and leaf,net photosynthetic rate(Pn),stomatal conductance(Gs),intercellular CO2 concentration(Ci),antioxidant enzyme activity(SOD,POD),membrane lipid peroxidation(MDA) content,soluble protein,glutamine synthetase(GS) activity,nitrate reductase(NR) activity,and amino acid contents were investigated to observe the changes within different nitrogen fertilizer levels under high temperature. [Results] Results showed that the application of nitrogen granular fertilizer enhanced the net photosynthetic rate(Pn),stomatal conductance(Gs) and intercellular CO2 concentration(Ci),and boosted the antioxidant enzyme activity(SOD,POD).The contents of MDA were reduced in nitrogen treatments and soluble protein,glutamine synthetase(GS) activity,nitrate reductase(NR) activity,and amino acid contents were up-regulated. Our results showed that high temperature reduced the seed-setting rate and 1 000-grain weight of rice.While the application of nitrogen granular fertilizer can significantly increase the rice 1 000-grain weight and make up for a loss of rice final yield under heat stress.‘Ningjing 3’ was susceptible to high temperature stress,and its grain yield decreased to greater extent. [Conclusions] The application of nitrogen granular fertilizer can regulate the nitrogen metabolism levels and antioxidant