施氮量对粮饲兼用玉米子粒产量和饲用品质的影响

2017~2018年以主推粮饲兼用玉米陕科9号品种为材料，设0、90、180、270和360 kg/hm² 5个氮肥水平进行大田试验，测定不同氮肥处理下叶面积指数、产量和饲用品质和氮肥利用率等性状指标，分析施氮量对玉米子粒产量、饲用品质和氮肥利用率的影响。结果表明，随施氮量的增加，叶面积指数、SPAD值和生物量增加；子粒产量随施氮量的增加先增加后稳定，此时最佳施氮量为268 kg/hm²，产量增加64.4%。随着氮肥增加，氮肥农学效率呈先增加后降低，氮肥偏生产力降低。饲用品质分析显示，子粒蛋白质、淀粉和脂肪含量随着施氮量增加而增加，在氮肥270 kg/hm²处理下分别较不施氮处理增加2.4%、13.7%和22.5%；秸秆中性洗涤纤维和酸性洗涤纤维含量分别减少20.4%和18.1%，秸秆粗蛋白和体外干物质消化率分别增加22.5%和17.6%。适当增施氮肥改善玉米群体质量，增加产量和氮肥利用率，提高饲用价值。陕北灌区粮饲兼用玉米生产实践中，推荐适宜施氮量为268 kg/hm²。

Effects of Nitrogen Rates on Grain Yield and Forage Quality of Dual-Purpose Maize

From 2017 to 2018, the field experiment was carried out with Shaanke 9 as the material. The effects of different nitrogen fertilizer ratels(0, 90, 180, 270 and 360 kg/ha) on the leaf area index, yield, feed quality and nitrogen utilization rate of maize. The results showed that nitrogen application significantly increased leaf area index, SPAD value and biomass. Nitrogen application increased maize yield by 64.4%, compared to N0. Nitrogen use efficiency increased first and then decreased with the increase of nitrogen application, and the increase of grain yield and nitrogen use efficiency was the largest under 268 kg/ha treatment. The maximum crude protein, starch and fat content of the N270 treatment increased by 2.4%, 13.7%, and 22.5% respectively, compared with N0. The NDF and ADF content of the N270 treatment increased by20.4% and 18.1% respectively, compared with N0. The crude protein and IVDMD of the N270 treatment increased by 22.5% and 17.6% respectively, compared with N0. It can be concluded that proper application of nitrogen fertilizer can improve the quality of corn population, increase the yield and nitrogen utilization rate, and improve the feeding value. Therefore, 268 kg/ha is recommended as the suitable nitrogen fertilizer for grain and forage maize production in the North Shaanxi irrigation area.