为研究播种时间对季节性栽培紫花苜蓿（Medicago sativa）产量及其影响因子的影响，以紫花苜蓿“维多利亚”品种为试验材料，于2009-2011年在阜南、淮安两地进行田间试验。结果表明，秋播、春季刈割2茬的栽培模式下，随播期推迟，紫花苜蓿的各生长性状和产量均呈下降趋势。其中，淮安试验点9月6日播种的紫花苜蓿第1茬初花期平均株高达到91．91cm，比10月24日播种高出1.14倍；相应地，9月6日播种的紫花苜蓿鲜、干物质产量也最高，第1茬分别达到4．37和1．05kg·m^-2。对产量影响因子的分析发现，紫花苜蓿干物质产量分别与株高、分枝数和单株干质量呈显著（P〈0．05）或极显著（P〈0．01）相关。通径分析发现，株高和单株干质量是紫花苜蓿产量的最主要影响因子。结果显示，早播主要通过促进株高生长、增加单株干质量来提高饲草的干物质产量。综合2年试验结果可以认为，季节性栽培紫花苜蓿在沿淮地区的适宜播种时间在9月至10月上旬。%In order to explore the optimum sowing date of alfalfa (Madicago sativa) in seasonal planting system in Huai River region, effects of autumnal sowing date on growth characteristics and forage yield were investigated in field experiments at Funan and Huaian from September 2009 to June 2011. The results showed that in the seasonal planting system (autumn sowing and twice-cutting in next spring), growth characters and forage yield reduced gradually with the autumn sowing date delayed. The average plant height at the early bloom stage in the first cutting was 91.91 cm for the sowing date of September 6, which was near double that of October 22 (42.90 cm) on the Huaian experiment site. Accordingly, the forage yield on the sowing date of September 6 was the highest, 4.37 kg ·m-2 in fresh weight and 1.05 kg·m-2 in dry matter. Forage yield was positively correlated (P〈0.01) to plant height, shoot number and dry weight per plant (P〈0.01). According to the path analysis results, plant height and dry weight per plant were the most primal factors for alfalfa forage yield. The results implied that the early-sowing in autumn improved the dry matter yield of alfalfa by increasing the plant height and dry weight per plant. The optimum sowing date of alfalfa for seasonal cultivation along Huai River region should be in Septem ber to early October.
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