Effects of nitrogen fertilizer application time on pod retention rate and seed yield of alfalfa

In order to improve pod retention rate and seed yield of alfalfa, effects of nitrogen fertilizer application time on pod retention rate, 1 000seed weight, seed yield of Medicago sativa cv. Xinmu No.4 were studied. The results showed that the pod retention rate, the 1 000seed weight and seed germination rate with the treatment of fertilized at returning green stage were higher than that in the other treatments which was 63.87%, 2.01 g and 85.33%, respectively. However, the pods number per inflorescence and pod retention rate of this treatment were lower than that in the other treatments. The seed yield was highest if fertilized at the budding stage which was 802.16 kgha-1 and 2.05 times of control and the seed yield was higher if fertilized at branching stage which was 641.29 kgha-1 and 1.64 times of control. These results provided a theoretical basis for rational fertilization of alfalfa seed field.