为探究孕穗期冷水灌溉下粳稻籽粒灌浆过程中的干物质、氮素形成积累规律及氮代谢关键酶调控效应,以东农428和松粳10为材料,设置6个冷水灌溉持续时间(0、3、6、9、12和15 d), 分析孕穗期冷水灌溉对寒地粳稻籽粒灌浆过程中的干物质、氮素积累及氮代谢关键酶活性的影响。结果表明,与对照相比,孕穗期冷水灌溉下,寒地粳稻产量及籽粒干物质积累量的变化规律一致,冷水灌溉持续时间越长,产量及籽粒干物质积累量降幅越大。冷水灌溉下,寒地粳稻籽粒干物质积累量降低,除与籽粒干物质最大相对积累速率降低有关外,还与结实率降低、有效穗数和每穗总粒数减少有关。冷水灌溉可提高寒地粳稻籽粒全氮、蛋白氮、成熟期籽粒粗蛋白含量及灌浆前期籽粒谷氨酰胺合成酶(GS)活性。冷水灌溉6 d可显著提高籽粒谷草转氨酶(GOT)及谷丙转氨酶(GPT)活性,冷水灌溉9~15 d可显著降低其活性。短期冷水灌溉下(3~6 d),寒地粳稻通过增强有机氮同化过程,促进蛋白质合成,使籽粒氮素含量增加;长期冷水灌溉下(9~15 d),籽粒有机氮同化过程受到抑制,影响氨基酸和蛋白质的合成,最终导致籽粒氮素增幅下降。籽粒全氮、蛋白氮和淀粉颗粒态结合蛋白是不同耐冷性品种响应冷水胁迫的差异产物,其含量可作为耐冷性鉴定的指标。

In order to understand how cold-water irrigation at booting stage affects the dry matter and nitrogen accumulation of grain in rice in cold-region, two japonica rice (Dongnong 428 and Songjing 10) were subjected to cold water irrigation for 6 varying length of time (0, 3, 6, 9,12 and 15 d) at booting stage. The dry matter, nitrogen accumulation and enzyme activities involved in nitrogen metabolism of grain were measured,respectively. The results showed that grain dry matter accumulation and yield in rice in cold-region followed a similar trend, and decreased under cold-water irrigation at booting stage with increasing cold-water irrigation days compared with the control. Due to the decreased maximum accumulation rate, seed setting rate, productive panicle number, grain number per panicle, grain dry matter accumulation decreased. The total nitrogen, protein nitrogen of grain, protein content of mature grain, and glutamine synthetase activity at early grain filling stage increased under cold-water irrigation. The gutamic-pyruvic transaminase and glutamic-oxaloacetic transaminase activities in grain significantly increased under 6 d of cold-water irrigation, whereas significantly decreased under 9-15 d of cold-water irrigation. The increase in total and protein nitrogen contents was due to the enhancement of grain nitrogen assimilation and protein synthesis ability under short term (3-6 d) cold-water irrigation, however, the process of nitrogen assimilation was inhibited, affecting the synthesis of protein and amino acid, eventually leading to a reduction in the growth rate of grain nitrogen content under long term(9-15 d) cold-water irrigation. Given grain total nitrogen, protein nitrogen and granule starch protein content varied with cold-water treatment duration and cultivar, they can be used as comprehensive evaluation indicators for cold resistance.