施氮对高寒区垂穗披碱草饲草生产性能及营养品质的影响

为探究高寒区施氮对垂穗披碱草饲草生产性能和营养品质的影响，本研究以建植第二年的垂穗披碱草（Elymus nutans）为研究对象，设置不同施氮处理：即纯氮N0（0 kg·hm^-2），N10（100 kg·hm^-2），N15（150 kg·hm^-2），N20（200 kg·hm^-2），N25（250 kg·hm^-2），N30（300 kg·hm^-2）处理，旨在确定高寒区垂穗披碱草刈割型草地的合理施氮量。结果表明：施氮处理提高了垂穗披碱草的生产性能，显著增加了垂穗披碱草的分蘖数、株高和干草产量，其中干草产量较不施氮处理的平均增幅为48.34%；并且施氮处理能够改善垂穗披碱草的营养品质，显著提高了其粗蛋白（Crude protein，CP）、粗脂肪（Ether extract，EE）、淀粉含量，其中粗蛋白含量较不施氮处理的平均增幅为49.67%。中性洗涤纤维（Neutral detergent fiber，NDF），酸性洗涤纤维（Acid detergent fiber，ADF）和粗纤维（Crude fiber，CF）含量随施氮量的增加呈先降低后升高趋势；一定的施氮处理（N10，N15，N20，N25）显著降低杂草的株高和密度，在N25处理下冷地早熟禾（Poa crymophila）、芸香叶唐松草（Thalictrum rutifolium）和沼生水马齿（Callitriche palustris L.）的密度较不施肥处理分别降低了27.52%，57.69%和35.21%，施氮处理能够有效抑制非播种草种的生长。综合分析得出，在果洛高寒区施氮量为250 kg·hm^-2时，垂穗披碱草的产草量和品质最优，且经济效益最好。

Effects of Nitrogen Application on Production Performance and Nutritional Quality of Elymus nutans in Alpine Region

This study was aimed to explore the effects of nitrogen application on production performance and nutritional quality of Elymus nutans in the alpine region. Elymus nutans grassland of the second year planted were used as experimental materials,and different nitrogen application treatments were set up:pure nitrogen (N):N0(0 kg·hm^-2),N10(100 kg·hm^-2),N15(150 kg·hm^-2),N20(200 kg·hm^-2),N25(250 kg·hm^-2),N30(300 kg·hm^-2). The reasonable amount of nitrogen application for Elymus nutans cutting grassland in alpine region was determined. The results showed that:nitrogen application improved the production performance of Elymus nutans,significantly increased the number of tillers,plant height and hay yield of Elymus nutans,and the average increase of hay yield was 48.34% compared with no nitrogen application. Moreover,nitrogen application improved the nutritional quality of Elymus nutans,and significantly increased the contents of crude protein (CP),ether extract (EE) and starch,in which the average increase of crude protein content was 49.67% compared with no nitrogen application. The contents of neutral detergent fiber (NDF),acid detergent fiber (ADF) and crude fiber (CF) decreased at first and then increased with the increase of nitrogen application rate. A certain amount of nitrogen application (N10,N15,N20,N25) significantly reduced the height and density of forbs. Under N25 treatment,the densities of Poa crymophila,Thalictrum rutifolium and Callitriche palustris L. decreased by 27.52%,57.69% and 35.21%,respectively,compared with no fertilization treatment,and the growth of non-seeding grass were effectively inhibited. Comprehensive analysis of the data showed that the hay yield and quality of Elymus nutans were the best when the nitrogen application rate was 250 kg·hm^-2,and the economic benefit was the best in Guoluo alpine region.