水氮耦合对直播早籼稻苗期低温冷害的调控效应

Regulatory Effects of Water-Nitrogen Coupling on Low Temperature Chilling Damage of Direct-Seeded Early Indica Rice at Seedling Stage

为探究水氮耦合对直播早籼稻苗期低温冷害的调控作用,以耐冷品种湘早籼6号和冷敏感品种中嘉早17为供试材料,设置适温不施氮(CK)、低温不施氮(LT-0N)、低温低氮(LT-LN)、低温高氮(LT-HN)、低温淹水不施氮(LTF-0N)、低温淹水低氮(LTF-LN)和低温淹水高氮(LTF-HN)7个处理,处理5d,分析秧苗农艺性状、抗氧化酶活性、渗透调节物质、氮代谢相关酶与光合酶活性、内源激素含量等生理生态特性。结果表明,水氮耦合可缓解低温冷害对直播早籼稻造成的伤害。与LT-LN处理相比,LT-HN处理5d后冷敏感品种中嘉早17的苗高、根数、最大根长、鲜重、干重、顶部第1和第3片叶长显著增加;与LTF-0N处理相比,LTF-LN和LTF-HN处理5d后,不同耐性品种的根数、根长、鲜重和顶部第3片叶长显著增加,LTF-LN处理的根数和鲜重高于LTF-HN处理。与LT-0N处理相比,LT-HN和LTF-LN处理显著增加冷敏感品种中嘉早17叶片氮代谢相关酶和光合酶活性、硝态氮、叶绿素和内源生长促进类激素含量,但降低了叶片抗氧化酶活性、可溶性蛋白、渗透调节物质和内源生长抑制类激素含量,高氮和淹水低氮处理可对直播早籼稻苗期低温冷害起到缓解作用。

In order to study the control methods of water-nitrogen coupling on low temperature chilling damage of direct-seeded early indica rice at the seedling stage,the cold-tolerant cultivar Xiangzaoxian 6 and cold-sensitive cultivar Zhongjiazao 17 were used as materials,and seven treatments including ambient temperature no nitrogen(CK),low temperature plus no nitrogen(LT-0N),low temperature plus low nitrogen(LT-LN),low temperature plus high nitrogen(LT-HN),low temperature flooding plus no nitrogen(LTF-0N),low temperature flooding plus low nitrogen(LTF-LN)and low temperature flooding plus high nitrogen(LTF-HN)were established for five days to analyse the physiological characteristics such as agronomic characters,antioxidant enzyme activities,osmotic regulation substances,nitrogen metabolism-related enzymes and photosynthase activities,endogenous hormone contents of rice seedlings.The results showed that water-nitrogen coupling treatments could alleviate the injury caused by low temperature chilling damage to direct-seeded early indica rice,compared with LT-LN treatment,the seedling height,root number,maximum root length,fresh weight,dry weight,T1(the first leaf from top)leaf length and T3(the 3rd leaf from top)leaf length of cold-sensitive cultivar Zhongjiazao 17 significantly increased after five days of LT-HN treatment;compared with LTF-0N treatment,the root number,root length,fresh weight and T3 leaf length of different tolerant cultivars increased significantly after five days of LTF-LN and LTF-HN treatments,the number of roots and fresh weight were higher in LTF-LN than that in LTF-HN.Compared with LT-0N treatment,LT-HN and LTF-LN treatments significantly increased the nitrogen metabolism-related enzymes,photosynthase activities,nitrate nitrogenin,chlorophyll and endogenous growth-promoting hormone contents in leaves of the cold-sensitive cultivar Zhongjiazao 17,but decreased leaf antioxidant enzyme activities,soluble protein,malonic dialdehyde,and endogenous growth-inhibiting hormones contents,high nitrogen and flooding low nitrogen treatments could alleviate low temperature cold damage in seedlings of direct-seeded earlyindica rice.