Effect Of Planting Technique On The Growth, Yield And Nutrients Accumulation Of Chinese Milk Vetch (Astragalus Sinicus L.)

Chinese milk vetch (Astragalus sinicus L.) is the main winter green manures in paddy field of southern China. Pot experiments and field experiments were carried out to study the effect of varieties, sowing date, seeding quantity, rhizobium treatment, optimum fertilizer amount, residual effect of N, P, K fertilizer, shading and soil water content on the growth, yield and nutrients accumulation of Chinese milk vetch, hoping to provide theoretical basis for the production and utilization of Chinese milk vetch. The main results showed as follows:(1) The difference exist among the seven varieties of Chinese milk vetch in the two areas. The results showed that the branches and compound leaves per plant of the Chinese milk vetch in Honghu were higher than Huangpi's, but the shoot height and apparent leaf area of Chinese milk vetch in Huangpi were higher than Honghu's. The dry matter yield of different varieties in the same area were also discrepancy, the yield of Fengcheng were highest in Honghu, arrived at 1914 kg/hm2, and the yield of Yijiang were highest in Huangpi, arrived at 1864 kg/hm2. The dry matter yield of the same variety were different in two areas, the yield of Daqiao, Yujiang, Fengcheng and Yuefei in Honghu were higher than Huangpi's, and others were lower than Huangpi's. The nutrients contents of Chinese milk vetch were different in the two areas, N contents of Chinese milk vetch in Huangpi were higher than Honghu's, but P, K contents in Honghu were higher than Huangpi's. The C, N, K accumulation of Fengcheng were highest in Honghu, and the P accumulation of Yijiang were highest in Honghu, all the nutrients accumulations of Yijiang were highest in Huangpi. In conclusion, Fengcheng and Yuefei were the optimal variety in Honghu area, Yijiang and Pinghu were the optimal variety in Huangpi area.(2) The shoot height, compound leaves per plant, apparent leaf area, weight per plant decreased as the sowing date postponed. Fresh yield decreased prominently as the sowing date postponed, sowing date at 25th September could get the highest yield, reached to 31833 kg/ha. Sowing date at 2nd October could get the highest seed yield,227 kg/ha.N,P,K,Cu contents of the shoot decreased as the sowing date postponed, but Fe and Mn contents increased when the sowing date later than 30th October, while there was no difference among the treatments with the Ca,Mg,Zn contents. The nutrients accumulation decreased as the sowing date postponed. The study showed that sowing date had great effect on Chinese milk vetch, the last ten-days period of September and the first ten-days period of October was the best sowing date under this condition of experiment.(3) The branches per plant, compound leaves per plant, weight per plant decreased as the seeding quantity increased. Fresh yield increased as the seeding quantity increased. the difference significantly among the seeding quantity from 7.5 kg/hm2 to 30.0 kg/hm2. but no significant difference among the seeding quantity increased more than 30.0 kg/hm2. The seeding quantity with 15.0 kg/hm2 had the highest seed yield, and then seed yield decreased as the seeding quantity increased. There was no influence of seeding quantity on nutrient content, but all the nutrients accumulation increased significantly as the seeding quantity increased. The study showed that seeding quantity with 30.0 kg/hm2 was the best choice under this condition of experiment.(4) The growth index of Chinese milk vetch with rhizobium treatment were better than the control treatments without rhizobium, the fresh yield was increased 26.7-47.7% than control, and the seed yield was increased 24.4-32.6% than control. The N content was increased with the treatment of rhizobium, but the treatment with rhizobium had no influence to the P, K, Ca, Mg, Fe, Mn, Cu, Zn. The nutrients accumulation were higher than control's. In this trial, the rhizobium D and E were optimal for the Chinese milk vetch of Yijiang.(5) The yield of Chinese milk vetch with the fertilizer treatments increased significantly, which increased 40-145% than no-fertilizer treatment. The N fertilizer had better yield-increasing effect than P, K fertilizer. When the N, P2O5, K2O fertilizer amount were 112.5,45.0,45.0 kg/hm2, the Chinese milk vetch got the highest yield with 20274 kg/hm2, and the C, N, P2O5, K2O accumulation were 981.0,54.4,12.8,58.7 kg/hm2 respectively.(6) The shoot height, branches per plant, compound leaves per plant, apparent leaf area and SPAD value of Chinese milk vetch applied with N, P, K fertilizer in the rice season were all better than treatments without N, P, K fertilizer. The Chinese milk vetch fresh yield of treatments with N, P, K fertilizer applied in the rice season were increased 36.2-48.2%,10.8-43.2%,25.6-55.6% than the treatments without N, P, K fertilizer respectively. In conclusion, the Chinese milk vetch got the highest yield and nutrient accumulation when N, P2O5, K2O fertilizer amount reached to 142.4 kg/hm2,112.5 kg/hm2 and 81.0 kg/hm2 in the rice season.(7) The survival seedlings under shading were more than no-shading, the seedling mortality increased as the shading degree increased. In the early growing stage, the shoot height increased as the shading degree increased, but compound leaves per plant, apparent leaf area and SPAD value decreased as the shading degree increased. As the growth period propelled, the difference among the treatments of the indexes diminished. The shading degree had significant influence on the yield of the three varieties, the yield of Yijiang were higher than other varieties under the no-shading and 40% shading condition, the yield of Zhezi were highest under the 75% shading condition. The content of carbon decreased as the shading degree increased, but the N, P, K contents increased as the shading degree increased. Shading also had influence on the nutrients accumulation of the three varieties, the C, P, K accumulation of Yijiang and the N accumulation of Xinyang were highest under the no-shading condition, the C, P, K accumulation of Zhezi and N accumulation of Yijiang were highest under the 40% shading condition, all the nutrients accumulation of Zhezi were highest under 75% shading condition. In conclusion, Zhezi was suitable interplant in the paddy.(8) The soil mass water content was between 30-40%, which beneficial to the seedling emergence and seedling growth.In conclusion, Fengcheng and Yuefei were the optimal variety in the Honghu area, Yijiang and Pinghu were the optimal variety in the Huangpi area. The last ten-days period of September and the first ten-days period of October was the best sowing date under this condition of experiment. The seeding quantity with 30.0 kg/hm2 was the best choice under this condition of experiment. The treatments with rhizobium D and E were the best. When the N, P2O5, K2O fertilizer amount were 112.5,45.0,45.0 kg/hm2, the Chinese milk vetch got the highest yield. The Chinese milk vetch got the highest yield and nutrient accumulation when N, P2O5, K2O fertilizer amount reached to 142.4 kg/hm2,112.5 kg/hm2 and 81.0 kg/hm2 in the rice season. Zhezi was suitable interplant in the paddy. The soil mass water content was between 30-40%, which beneficial to the seedling emergence and seedling growth.