施氮量对江汉平原中低产田小麦产量及氮素吸收利用的影响

为探究江汉平原地区中低产田小麦种植的最适施氮量，以适宜长江中下游流域种植的小麦品种郑麦9023与扬麦23为材料，设置0、135、180和225 kg·hm^-24个纯氮施用量，研究施氮量对小麦籽粒产量及产量构成、氮素利用效率以及部分农艺性状的影响。结果表明，当施氮量在0～225 kg·hm^-2范围内时，随着施氮量的增加，氮肥偏生产力和氮肥农学利用效率逐渐降低，而小麦的旗叶相对叶绿素含量(SPAD)值、有效穗数、穗粒数和生物量逐渐增加，同时籽粒产量在施氮量为225 kg·hm^-2时最高，但与180 kg·hm^-2施氮量处理并无显著差异。在0～180 kg·hm^-2施氮量范围内，氮肥的增施可显著增加植株干物质积累量、氮素积累量和收获指数。在180 kg·hm^-2施氮量处理的基础上继续增施氮肥至225 kg·hm^-2，并未显著增加小麦各生育时期植株干物质积累量。在不同施氮量处理下，扬麦23较郑麦9023平均增产19.8%，且有效穗粒数较多、穗...

Effects of Nitrogen Application Rate on Wheat Yield and Nitrogen Absorption and Utilization in Low- and Medium-Yield Fields in the Jianghan Plain

The objective of this study is to determine the optimum nitrogen application rate for wheat plantation in low- and medium-yield fields of the Jianghan Plain. The effects of different pure nitrogen application rates （0， 135， 180， and 225 kg·hm^-2） on the grain yield， yield composition， nitrogen use efficiency， and some agronomic traits of two wheat cultivars， namely Zhengmai 9023 and Yangmai 23， were studied. The two cultivars were selected owing to their suitability for planting in the middle and lower reaches of the Yangtze River. The results showed that the partial productivity and the agronomic use efficiency of nitrogen fertilizer gradually decreased but the SPAD value of wheat flag leaf， panicle number， grain number and biomass gradually increased with increasing nitrogen application rate from 0 to 225 kg·hm^-2. Meanwhile， grain yield was the highest at the nitrogen application rate of 225 kg·hm^-2， despite being insignificant compared with nitrogen application rate of 180 kg·hm^-2. Dry matter accumulation， nitrogen accumulation， and harvest index significantly increased with increasing nitrogen application rate from 0 to 180 kg·hm^-2. However， the application rate of 225 kg·hm^-2 did not significantly increase wheat dry matter compared with 180 kg·hm^-2 in each growth period. Compared with Zhengmai 9023， Yangmai 23 produced a 19.8% higher yield on average under different nitrogen application rates， presenting marked yield stability with high effective grain number per spike number， stable panicle number， 1 000-grain weight， nitrogen absorption and utilization efficiency， and harvest index. Additionally， the results of redundancy analysis showed that apparent nitrogen use efficiency， nitrogen agronomic use efficiency， and nitrogen partial productivity were positively （P<0.01） correlated with wheat grain yield. Therefore， considering both yield and input， the optimum nitrogen application rate for wheat plantation in low- and medium-yield fields of the Jianghan Plain is 180 kg·hm^-2， which is accompanied by higher nitrogen absorption and utilization efficiency. The results from this research provide a technical reference for increasing wheat productivity in low- and medium-yield fields in the Jianghan Plain and the efficiency of applying nitrogen fertilizers.