Abstract: In order to understand the relationship between row spacing,irrigation rate and redundancy of Medicago sativa L.population and achieve the population structure with higher seed yield,the effects of row spacing and irrigation rate on above ground biomass,underground biomass and reproductive allocation were investigated by a field trial.The results shown: aboveground and underground biomass were negatively correlated with reproductive allocation rate(P<0.01) with a correlation coefficient of-0.910 and-0.839,respectively;presentation seed yield were positively correlated with reproductive allocation rate(P<0.01,R²=0.878).This is a reflection of the life history strategy theory in alfalfa seed production,i.e.increase in the allocation of limited energy to vegetative growth would lead to a reduction in energy allocation to the reproductive tissues and therefore lead to a reduced presentation seed yield.A optimum seed production of Medicago sativa L.cv.Gannong No.3 was obtained from a population with plant density of 860,000 /hm²,reproductive shoot density 690,000/hm²,seeding rate 2.8 kg/hm²,row spacing 1.0 m and irrigation rate 900 m³/hm².Under such a population structure and management regime,the reproductive allocation rate,harvest index,and presentation seed yield were the highest.When irrigation rate was higher than 900 m³/hm²,the vegetative growth was over-flourishing,leading to greater amount of growth redundancy but lower reproductive allocation rate,harvest index,and seed yield.

Key words: Alfalfa, Population, Row spacing, Irrigation rate, Growth redundancy, Seed yield

摘要： 研究播种行距和灌水量对紫花苜蓿(Medicago sativa L.)地上、地下生物量和表现种子产量的影响,以揭示行距和灌水量与紫花苜蓿种群生长冗余的关系,得出紫花苜蓿获得较高种子产量的种群结构。结果表明:①地上和地下生物量与繁殖分配率呈极显著负相关,相关系数分别为-0.910和-0.839,表现种子产量与繁殖分配率呈极显著正相关,R²=0.878,说明营养生长分配的增加导致生殖生长能量的减少,使繁殖分配率降低,表现种子产量降低;②在甘肃武威地区甘农3号紫花苜蓿(Medicago sativaL.cv.Gannong No.3)种子田获得较高种子产量的种群结构为:密度86万株/hm²,有效分枝69万株/hm²,相应的管理措施为:播种量2.8 kg/hm²,行距1.0 m,灌水量900 m³/hm²,在该种群结构和管理下,有限能量向生殖部分分配的比例最大,繁殖分配率和收获指数最高,表现种子产量最高,在一个生长季内如果灌水量大于900 m³/hm²,则营养生长过旺,产生大量生长冗余,繁殖分配率和收获指数下降,表现种子产量降低。

关键词: 紫花苜蓿, 种群, 行距, 灌水量, 生长冗余, 种子产量