稻–麦轮作下9000kg hm(–2)产量水平扬麦20的群体质量及花后光合特征

Population Quality and Photosynthetic Characteristics after Anthesis in Yangmai 20 with Yield Potential of 9000 kg ha^(-1) in Rice–Wheat Rotation System

在稻麦两熟制条件下,于2010—2011和2011—2012年度,通过氮肥施用量、施用时期及比例的调控,建立了扬麦20不同产量水平群体,比较≥9000 kg hm–2群体(P1)与<9000 kg hm–2群体(P2)的产量构成、群体质量及花后光合特征,为稻茬小麦大面积高产提供理论依据和技术支撑。P1较P2群体产量高约10%,每穗粒数高约5.5%,差异显著,但两群体的穗数和千粒重差异不显著。P1群体的穗数、穗粒数和千粒重分别为482~538万hm–2、47~49粒和34~39 g。籽粒产量与孕穗和开花期叶面积指数(LAI)及花后LAI衰减率和光合势呈抛物线关系,与乳熟期LAI、粒(重)/叶比和群体生长率呈显著线性正相关。两年度试验结果表明P1群体具有以下特征,孕穗期、开花期和乳熟期的LAI分别为6.5~7.0、5.0~6.0和4.0~4.5;粒(数)/叶比为0.37~0.39,粒(重)/叶比为13.5~14.5;花后LAI衰减率、群体生长率、光合势和净同化率分别为0.13~0.15 d–1、19~20 g m–2 d–1、103×104~118×104 m2 d hm–2和9~11 g m–2 d–1。花后21d和28 d,剑叶SPAD值、净光合速率、丙二醛(MDA)含量及3种抗氧化酶(CAT、POD和SOD)活性与产量相关性均达极显著水平。研究表明,稻–麦轮作体系中,扬麦20达到9000 kg hm–2产量水平的栽培技术关键点是获得适宜穗数的基础上,主攻每穗粒数与千粒重的协调增加,使群体在花前具有较高的光合面积和光合速率,花后光合面积衰减速率低,维持较高的光合面积,从而充分积累花后光合物质,在适宜库容基础上保障对库充实的需求。

The objective of this study was to fine-tune cultivation techniques for large-scale high yielding（ ≥9000 kg ha–1） wheat production in rice–wheat rotation system. Wheat（Triticum aestivum L. cv. Yangmai 20） populations with yield level ≥9000 kg ha–1（P1） and 9000 kg ha-1（P2） were established through managing application amount, timing and splitting ratio of nitrogen fertilizer in the 2010–2011 and 2011–2012 growing seasons. The grain yield and grain number per spike in P1 population were 10.0% and 5.5% higher than those of P2 population with significant difference between each other. However, the differences in spike number and 1000-grain weight between P1 and P2 were not significant. The yield components of P1 population were 4.82–5.38 million spikes per hectare, 47–49 grains per spike, and 34–39 g of 1000-grain weight. Grain yield of different populations showed parabolic correlations with leaf area index（LAI） at booting and anthesis stages, leaf area decreasing rate and photosynthetic potential after anthesis, as well as significantly linear correlations with LAI at milk-ripening stage, grain weigh per square centimeter leaf and population growth rate. According to the experiments results in two years, P1 population was characterized with dynamic LAI of 6.5–7.0 at booting, 5.0–6.0 at anthesis and 4.0–4.5 at milk-ripening stage; grain/leaf ratio of 0.37–0.39 grains cm–2 leaf and 13.50–14.50 mg grain cm–2 leaf; LAI decrease rate of 0.13–0.15 d–1 after anthesis; population growth rate of 19–20 g m–2 d–1 after anthesis; photosynthetic potential of 1.03–1.18 million m2 d ha–1 after anthesis; and net assimilation of 9–11 g m–2 d–1 after anthesis. At the stages of 21 and 28 days after anthesis, the SPAD reading, net photosynthetic rate, malondialdehyde content, and activities of antioxidant enzymes（CAT, POD, and SOD） in flag leaves were significantly correlated with grain yield. Our results suggest the following key points of cultivar potential for 9000 kg ha–1 yield potential of Yangmai 20 in rice–wheat rotation system are suitable population spike number as the basis; synchronous increases of grain number per spike and 1000-grain weight; high photosynthetic area and photosynthetic rate before anthesis; slow decrease of photosynthetic area after anthesis with its maintainable high level, and an abundant accumulated assimilate meeting to the sink enrichment.