Abstract: The effect of nitrogen fertilizer and planting density on dry matter accumulation,nitrogen absorption,accumulation and distribution of alfalfa organ and seed yield was studied through field experiments.Results showed that the high level of nitrogen and low planting density(N3D1) enhanced dry matter and nitrogen accumulation of each organ.Nitrogen accumulation was varied for different nitrogen levels and planting densities.Stem was the main organ of nitrogen accumulation in the treatment of high planting density and low or medium nitrogen level.However,nitrogen mainly accumulated in flower pods in the treatment of low planting density and high nitrogen level.Dry matter and nitrogen accumulation increased with nitrogen level increasing.The highest dry matter and nitrogen accumulation were tested in treatment N3D1 compared with others.The average contents of dry matter accumulation in root,stem,leaf and flower pod of treatment N3D1 were 8.65,19.02,2.35 and 5.98 g·plant^-1,respectively.Nitrogen contents in each organ were12.23,15.01,3.62,15.70 mg·plant^-1,respectively.The optimal nitrogen application level and planting density were 150 and 3 kg·hm^-2.Under the optimal condition,the seed yield of alfalfa can reached 740.36 kg·hm^-2.

Key words: Nitrogen applying level, Planting density, Alfalfa, Seed yield

摘要： 通过田间试验研究了施氮量、种植密度对紫花苜蓿(Medicago sativa L.)各器官干物质积累、氮素吸收、积累分配及种子产量的影响。结果表明:高氮稀植(N3D1)处理有利于苜蓿各器官干物质及氮素积累;氮素积累趋势因施氮量、种植密度不同而异:低氮高密、中氮高密处理下氮素积累以茎杆为中心,高氮低密处理下,花荚为氮素积累中心,施氮可显著提高干物质及氮素积累量。各处理中干物质及氮素积累量均以N3D1处理最高,该处理下苜蓿根、茎、叶、花荚中干物质量为8.65,19.02,2.35,5.98g·株^-1,氮素积累量分别为12.23,15.01,3.62,15.70mg·株^-1。本研究中当施氮量为150kg·hm^-2,密度为3kg·hm^-2时,种子产量最高达到740.36kg·hm^-2。

关键词: 施氮量, 种植密度, 紫花苜蓿, 种子产量