氮肥运筹对弱筋小麦群体指标与产量和品质形成的影响

以弱筋小麦品种扬麦9号和宁麦9号为材，研究了不同施氮水平及基追比对群体指标、产量和品质的影响。结果表明，孕穗期叶面积指数（LAI）随施氮量的增加而提高；小麦籽粒产量及成熟期生物产量、花后干物质积累量与施氮量均呈二次曲线关系；籽粒蛋白质含量、湿面筋含量与施氮量呈极显著正相关。增加后期追氮比例及同比例2次追氮均提高了成熟期生物产量、花后干物质积累量、茎蘖成穗率、孕穗期LAI、籽粒产量、蛋白质含量和湿面筋含量。花后干物质积累量、成熟期生物产量、成穗数、茎蘖成穗率与产量呈显著或极显著正相关，拔节期、孕穗期、开花期和灌浆期LAI与产量呈显著或极显著二次曲线关系。弱筋小麦实现优质和产量7 000 kg hm^-2的氮肥运筹技术以施氮量200 kg hm^-2和基肥∶拔节肥∶孕穗肥为7∶2∶1，其高产优质协调的关键群体调控指标，最适LAI为6.9，花后干物质积累量和成熟期生物产量分别为5 300和16 500 kg hm^-2，成穗数为466×104 hm^-2，茎蘖成穗率为50%。

Effects of Nitrogen Strategies on Population Quality Index and Grain Yield & Quality in Weak-Gluten Wheat

Improving grain quality based on high yield is still a substaintial target in wheat production. It has been proved that the key factors contributing to high yield are the dry matter accumulation from flowering to maturity, the biomass at maturity, the optimal leaf area index (LAI), and the proper spike rate. These factors also act as the indexes to evaluate wheat population quality. However, the optimal population quality indexes vary in different specific wheat populations, and optimal cultivating techniques are unavailable due to lack of reliable population regulation indexes in weak-gluten wheat practice. It is very important to establish the optimal population quality index and develop corresponding nitrogen fertilization strategy for high-quality and high-yield production in weak-gluten wheat. In the present study, we employed two weak-gluten wheat cultivars, Yangmai 9 and Ningmai 9, to investigate the effects of nitrogen rates (0, 60, 120, 180, 240, and 300 kg ha^-1) and dressing ratios (8:2, 7:3, 6:4, 5:5, and 7:2:1 under nitrogen rate of 180 kg·ha^-1) on population index, grain yield, protein and gluten contents in 2003–2004. The results showed that leaf area index (LAI) at booting increased with increasing nitrogen rates. Grain yield, post-anthesis dry matter accumulation and biomass at maturing were parabolically related to nitrogen rates. The contents of protein and wet gluten in grains were positively correlated with nitrogen rates. While under the same nitrogen rate of 180 kg ha^-1, post-anthesis dry matter accumulation, biomass at maturity, spike number, spike rate, LAI at booting, grain yield, and contents of crude protein and wet gluten were enhanced with increasing dressing percentages, especially with dressing twice with the same percentage. Also, post-anthesis dry matter accumulation, biomass at maturity, spike number and spike rate were significantly correlated with grain yield. LAI at jointing, booting, anthesis and filling showed close relationships with grain yield. The results indicated that grain yield and quality could be improved synchronously under nitrogen rate of 200 kg ha^-1 based on dressing ratio of 7:2:1 in weak-gluten wheat. The corresponding population indexes for high-quality and grain yield in weak gluten wheat were 6.9 of the highest LAI at booting, 5 300 kg ha^-1 of post-anthesis dry matter accumulation, 16 500 kg ha^-1 of biomass at maturity, 466×10⁴ ha^-1 of spike number and 50% of spike rate.