Abstract: In order to understand the comprehensive influence of N supply on alfalfa, the effects of three N levels (N0 (0), N1 (51.75 kg·hm^-2), N2 (103.50 kg·hm^-2)) on the productivity, height and quality of Medicago sativa ‘Gannong No. 3' and M. sativa ‘Longdong' were studied in the Qinwangchuan of Gansu Province by randomized block design. Results showed that comprehensive influence was obvious under N supply, and productivity increased along with N fertilizer increased. The productivity of alfalfas reached the highest under N2 (103.50 kg·hm^-2) level and Gannong No. 3 was obviously better than Longdong. The highest fresh biomass and dry biomass of Gannong No.3 were 51005 kg·hm^-2 and 14856 kg·hm^-2, Longdong were 35486 kg·hm^-2 and 11217 kg·hm^-2. N supply also significantly increased the height of both alfalfa varieties. The change-trend for height was consistent with that of productivity, and Gannong No. 3 did better than Longdong. In addition, N supply could improve the nutrient quality of alfalfa, significantly reduce ADF, NDF and ash contents and increase crude protein and ether extract contents. The best N application rate was 103.50 kg·hm^-2.

Key words: Alfalfa, N, Biomass, Quality

摘要： 在甘肃兰州秦王川地区以甘农3号(Medicago sativa ‘Gannong No. 3')和陇东苜蓿(M. sativa 'Longdong')为材料,设置3个供氮水平处理N0(0),N1(51.75 kg·hm^-2)和N2(103.50 kg·hm^-2),对其产量、株高及营养品质进行测定,以探讨供氮对紫花苜蓿的综合影响。结果表明:供氮对紫花苜蓿综合影响明显,供氮能显著提高其产量,且产量随供氮水平的增加而增加,在N2水平下紫花苜蓿总产量最高,甘农3号的最高鲜草产量为51005 kg·hm^-2、干草产量为14856 kg·hm^-2,陇东苜蓿鲜草产量为35486 kg·hm^-2,干草产量为11217 kg·hm^-2,甘农3号明显优于陇东苜蓿;供氮还显著提高2个品种的株高,株高与产量变化趋势一致,甘农3号表现更佳;供氮也改善了紫花苜蓿营养品质,显著降低2个品种酸性洗涤纤维、中性洗涤纤维和粗灰分的含量,提高其粗蛋白和粗脂肪的含量。因此,从产量和营养品质综合考虑,该地区最佳施氮量为103.50 kg·hm^-2。

关键词: 紫花苜蓿, 氮, 产量, 品质