目的 本研究旨在明确弱光胁迫下不同弱光耐性品种在源库特征及叶片保护酶活性变化方面的差异,揭示其耐弱光胁迫的机制,为双季稻高产稳产新品种的选育及抗逆栽培提供理论指导。方法 以2个对弱光胁迫耐性存在显著差异的晚稻品种为材料,通过设置不同时期的遮光处理,研究弱光胁迫时期对晚稻不同耐性品种的源库特征及叶片保护酶活性的影响。结果 结果表明,不同时期弱光胁迫对晚稻生长有重要影响,分蘖期弱光胁迫下晚稻分蘖数、每穗粒数及总颖花量减少,叶面积下降,产量降低;幼穗分化期弱光胁迫下晚稻分蘖数和每穗粒数减少,总颖花量、叶面积、结实率均下降,产量降低;灌浆期弱光胁迫下水稻叶片净同化率降低,结实率和千粒重下降,产量降低。不同时期弱光胁迫对晚稻产量的影响表现为灌浆期>幼穗分化期>分蘖期。结论 耐弱光胁迫型品种能通过增加叶片的长宽度减少叶面积的下降,叶片含氮量保持相对稳定,叶片中SOD、CAT等保护酶活性保持在较高水平,POD活性保持相对稳定,叶片净同化率下降幅度小,在弱光胁迫下实现“强源”,减产率相对较低。弱光胁迫下具有较强的叶面积补偿能力和适宜氮含量以及较高的保护酶活性是水稻耐弱光胁迫的重要机制。

【Objective】The purpose of this study is to clarify the differences in sink-source characteristics and leaf protective enzyme activities of late rice with different tolerance to weak light stress, so as to reveal its tolerance mechanism, and lay a theoretical basis for the selection of new rice varieties with high and stable yield and stress-resistance cultivation.【Method】In order to reveal the effects of weak light stress at different stages on sink-source characteristics and leaf protective enzyme activities in late rice with different tolerance to weak light stress, two late rice were grown with shading at different stages. 【Result】The results showed that weak light stress at different stage exerted great influence on the growth of late rice. Shading at tillering stage decreased tiller number, grain number per panicle and total spikelet number, as well as leaf area and yield. Shading at panicle initiation stage decreased tiller number, grain number per panicle, total spikelet number, leaf area, seed setting rate and the yield. Shading at filling stage reduced the net assimilation rate of leaf, seed setting rate, 1000-grain weight and yield. Weak light stress had a greater influence on the source of late rice than on the sink. The effects of weak light stress on the yield of late rice were as follows: filling stage > PI stage > tillering stage. 【Conclusion】Under weak light stress, the type with strong tolerance could offset the decline of leaf area by increasing leaf length and width, maintaining relatively optimum leaf nitrogen content, and higher protective enzyme activities such as superoxide dismutase(SOD) and catalase(CAT) and a stabilized peroxide(POD) activity in leaf with slight drops in net assimilation rate, strong “source” ability and less yield reduction rate. The stronger capability of leaf area compensation and nitrogen content maintaining, and higher level of protective enzyme activities in leaf are accountable for higher tolerance to weak light stress for rice.