Effects Of Different Cultivation Technique On The Growth And Seed Yield Of Chinese Milk Vetch(Astragalus Sinicus L.)

Field experiments were carried out to study the effect of sowing date, seeding rate, fertilizer application and rhizobium treatment on the growth, above ground biomass, seed yield and its components of Chinese milk vetch in Datonghu, Honghu city, Hubei province. The project aimed to provide technical guidance and theoretical basis for seed production of Chinese milk vetch. The main results showed as follows.(1) The height, weight per plant, and stem diameter of Chinese milk vetch were decreased as the sowing date was postponed. The seed yield would be influenced by sowing rate through branches, effective plants and pods. Sowing date after September decreased seed yield by 6.7%-34.9% compared with the end of September. The study showed that September was the best sowing date under this condition of experiment, and sowing earlier would be better without influence of the growth of preceding crop.(2) The seeding rate had no significant difference to the height, weight per plant and stem diameter of Chinese milk vetch from 7.5 kg/hm2 to 22.5 kg/hm2, then decreased a little, while decreased significantly until 37.5 kg/hm2. The first branch and racemes in unit area were the major factors controlling seed yield. With the yield test data, we considered established the seeding rate effect function of Chinese milk vetch, analyzed and got this conclusion: the suitable seeding rate to achieve high seed yield is 24.3 kg/hm2.(3) The growth indexes and yield of Chinese milk vetch with the NPK fertilizer application increased significantly. The seed yield would be influenced by fertilization through branches, effective plants and racemes, which increased by 13.3%-47.4%. According to the NPK fertilizer effect model on the seed yield of Chinese milk vetch, the suitable N, P2O5, the NPK fertilizer rate to achieve high seed yield is 47.9 kg/hm2, 67.3 kg/hm2 and 67.5 kg/hm2 respectively.(4) Basal dressing application of only one kind of micronutrient fertilizers among B, Mo, Zn or Co increased seed yield of Chinese milk vetch by 5.3%-13.8%. B fertilizer got the highest yield, following by Mo fertilizer. While four micronutrient fertilizers mixed, the growth indexes with spraying at seedling and flowing period treatment were the highest, then basal dressing. These two treatments could increase effective plants, branches and racemes significantly, the seed yield was increased by 17.7% and 9.6% respectively. While there was no difference between seed dressing treatment and the control treatment with growth and seed yield of Chinese milk vetch.(5) The height, weight per plant, stem diameter and SPAD value of Chinese milk vetch with seed dressing of rhizobium treatment were better than the control without rhizobium, the above ground biomass was increased by 28%. The growth indexes, N accumulation, branches, rameces and pods were increased with this treatment, the seed yield was increased by 34.4%. While there was no difference between rhizobium spraying treatment and the control treatment with growth nutrient accumulation and seed yield of Chinese milk vetch.In conclusion, September is the best sowing date for seed production of Chinese milk vetch in central China; the suitable seeding rate is 24.3 kg/hm2; seed dressing of rhizobium would be better; the NPK fertilizer rate to achieve high seed yield is 47.9 kg/hm2, 67.3 kg/hm2 and 67.5 kg/hm2 respectively is the best choice; spaying mixed micronutrient fertilizer of B, Mo, Zn, Co during seedling and full-bloom stage would be beneficial to seed yield improving.