刈割时期及高度对紫花苜蓿生育期及种子产量的影响

Effect of Cutting Time and Height on Reproductive Growth Stage and Seed Yield of Alfalfa

在甘肃酒泉研究了刈割时间、刈割高度对紫花苜蓿生育期、种子产量及产量因子的影响，结果表明：刈割对紫花苜蓿生育期有着显著的调控作用，分枝期刈割后苜蓿在花期持续了9d，而在结荚期和成熟期持续了41d，表现出先快后慢的生长节律。现蕾期刈割后开花期持续了15d，而结荚期和成熟期则持续了33d，表现出先慢后快的生长节律。不同刈割高度显著推迟了苜蓿进入花期及收获期时间，但没有改变生长节律。分枝期和现蕾期刈割均显著增加了枝条数／m^2及荚果数／花序，分枝期25cm留茬高度的刈割处理收获了最高种子产量（1118．08kg／hm^2），比对照增加了112．03kg／hm^2；现蕾期不同高度刈割均显著降低了种子产量。

A field experiment was carried out in Jiuquan, Gansu province, to evaluate the effects of two cutting times and three cutting heights on alfalfa reproductive characteristic, seed yield and seed yield components. The results showed that cutting times effeeted alfalfa reproductive rates. After the cutting of brunch-stem formed stage, alfalfa reproduction lasted 9 d on bloom stage and 41 d on pod-set and seed-fill stage, the growth rate was higher, and then slowed down. After bud stage cutting, alfalfa growth lasted 15 d on bloom stage and 33 d on pod-set and seed-fill stage, the reproduction rate was initially slow and then quickened. The cutting heights delayed reproductive growth stage and harvesting time with stubble height decreasing, but not change the reproductive rate. Shoots/m^2 and pods/raceme increased with the delay of cutting time. The highest seed yield （1 118.08 kg/ha） was obtained at the cutting of brunch-stem formed stage with 25 cm stubble height. Bud stage cutting decreased seed yield significantly.