氮素穗肥对杂交籼稻籽粒灌浆影响及其与淀粉合成关键酶活性间关系

Effect of Nitrogen Fertilizer Topdressing for Panicle Differentiation on Grain Filling of Hybrid indica Rice and Its Relationship with the Activities of Key Enzymes for Starch Synthesis

【目的】为明确氮素穗肥对杂交稻籽粒灌浆和淀粉合成关键酶活性的影响。【方法】选用两个直链淀粉含量差异较大的杂交稻品种锦优1319(高直链淀粉)和蓉优702(低直链淀粉),在不同的氮素穗肥处理下(设0、60、90和120 kg/hm^(2)4个纯氮水平,分别用CK、N1、N2、N3表示)研究氮素穗肥水平对籽粒灌浆和淀粉合成关键酶活性的影响。【结果】不同穗肥处理下杂交稻籽粒灌浆特性差异显著,且不同类型品种表现各异,其中氮素穗肥的施用显著降低了稻米的直链淀粉含量。锦优1319的Gmax和Gmean随氮素穗肥水平的变化均表现为N2>CK>N1>N3,而蓉优702则表现为N3>N2>CK>N1;施用氮素穗肥显著增加了花后5~25 d籽粒腺苷二磷酸焦磷酸化酶(ADPG)和淀粉分支酶(DBE)的活性,降低了花后5~15 d籽粒GBSS活性,降低了花后5~25 d籽粒淀粉合成酶(SSS)和SBE活性。【结论】高直链淀粉品种锦优1319籽粒灌浆的最佳氮素穗肥施用量低于低直链淀粉品种蓉优702:其中锦优1319的最佳氮素穗肥施用量为90 kg/hm^(2),蓉优702为120 kg/hm^(2)。施用氮素穗肥显著降低了GBSS、SSS的活性,加之SBE活性下降,DBE活性提高,最终降低稻米直链淀粉含量。本研究条件下,籽粒ADPG活性未对稻米直链淀粉含量产生显著影响。

【Objective】To elucidate the impact of nitrogen panicle fertilizer on the key enzymes involved in grain filling and starch synthesis in hybrid rice.【Methods】Two hybrid rice varieties,Jinyou 1319(high amylose)and Rongyou 702(low amylose),characterized by substantial differences in amylose content,were chosen for a study examining the effects of the levels of nitrogen fertilizer topdressing for panicle differentiation on the activities of key enzymes in grain filling and starch synthesis.Various nitrogen topdressing treatments were applied,representing four pure nitrogen levels(0,60,90,and 120 kg/hm^(2) denoted as CK,N1,N2,and N3,respectively).【Results】Grain filling characteristics of hybrid rice exhibited significant variations under different nitrogen fertilizer topdressing treatments,with diverse performances observed among different varieties.The application of nitrogen fertilizer topdressing notably decreased the amylose content of rice.Both Gmax and Gmean of Jinyou 1319 exhibited a trend of N2>CK>N1>N3 under different nitrogen fertilizer topdressing levels,while those of Rongyou 702 followed a tendency of N3>N2>CK>N1.The nitrogen fertilizer topdressing significantly increased the activities of ADPG and DBE in grains at 5-25 days after anthesis,reduced the activities of GBSS in grains at 5-15 days after anthesis,and decreased the activities of SSS and SBE in grains at 5-25 days after anthesis.【Conclusion】The optimal application rate of nitrogen fertilizer topdressing for panicle differentiation was lower for the high-amylose variety Jinyou 1319 compared to the low-amylose variety Rongyou 702:the optimal rate of nitrogen fertilizer topdressing for Jinyou 1319 was 90 kg/hm^(2),and for Rongyou 702,it was 120 kg/hm^(2).The nitrogen fertilizer topdressing significantly reduced the activities of GBSS and SSS,accompanied by a decrease in SBE activity and an increase in DBE activity,ultimately leading to a reduction in rice amylose content.Seed ADPG activity did not significantly affect rice amylose content in this study.