Studies On Production Of Alfalfa For Seasonal Utilization In Nanjing

Alfalfa(Medicago sativa L.)is a major forage crop and has a long cultivation history in China.However, its research and production in the farming regions of southern China is less due to the limit of ecological condition and soil. With the adjustment of agricultural structure and rapid development of stockbreeding.alfalfa production has been paid more attention in recent years,because it is an effective way to solve the problem of forage shortage in southeastern China.According to the ecological condition and planting system.alfalfa grown as an after crop in paddy field or intercropping with fruit trees in late autumn-spring for seasonal utilization.can increase the utilization of natural resources to produce plenty of forage and provide numerous benefits to the grower.Seasonal production of alfalfa on fallow farmland and under economic trees in winter-spring season will be the attemptable orientation of alfalfa production in the farming regions of southern China.The productivity and qulity of8less fall dormancy alfalfa cultivars(Sitel,Sanditi, Eureka,Sirive,WL-414and WL-525HQ)grown on winter-fallow farmland and grown in pot during spring in Nanjing were analyed. Moreover, the effect of nitrogen and phophorus fertilizer on a high fall dormancy alfalfa cultivar was also investigated on winter-fallow farmland.The purposes of this study were to select high yielding alfalfa cultivars,find out target characters and explore the effective cultivaring techniques of alfalfa for seasonal utilization.The results of varietal comparation trival on winter-fallow farmland showed as follows:8alfalfa cultivars could grow well and be harvested2times in following spring.There were much bigger varietal differences of yield components and dry matter accumulation than that of forage qulity.As superior performance on plant height,primary shoot number and crop growth rate,WL-414,WL-525HQ,Siriver and Derby got higher dry matter yields than other cultivars.Total dry matter yields of the above4cultivars were ranging from730.3to1460.3g/m2,whereas total crude protein yields were ranging from214.8to279.5g/m2.Sowed in following spring, potted alfalfa cultivars (The diameter of pot was22.3cm) showed significant difference in both forage productivity and feeding value.In the aspect of growth and regrowth characteristics, especially plant height, shoot number, single leaf area as well as growth rate.Eureka,WL-414.Siriver and WL-525HQ got the advantage over other cultivars. Dry matter yields of the4cultivars were between13.5and28.4g/pot when harvested2times. Compared with other cultivars. they also had higher crude protein yields and digestible dry matter yields.Carrying the fertilizer experiment on alfalfa in the field indicated that.nitrogen fertilizer could improve alfalfa yield significantly.but had a little effect on forage quality.Plant height.stem diameter.internode number.shoot number.leaf area.specific leaf area.crop growth rate and dry matter yield generally increased with the increase of nitrogen application rate.Furthermore.the treatments with nitrogen application rates of180kg/hm2and240kg/hm2got more crude protein yields and digestible dry matter yields than relatively low nitrogen application treatments.The results also showed that phophorus fertilizer had a limited influence on alfalfa production. Utilization of phophorus was benefit to accelerate growth and regrowth rate of plant height,promote regrowth of alfalfa and improve crude protein yields per square meter.Maximum total dry matter yield and crude protein yield was reached at300kg N/hm2.Addition of nitrogen and phophorus fertilizer could impact plant height, shoot number.leaf area.specific leaf area and growth rate greatly,which would increase alfalfa yield remarkably.Considering forage yield and quality,fertilization with nitrogen240kg/hm2and P2O5300kg/hm2was the optimal combination.All results above revealed that, plant height, shoot number.single leaf area and crop growth rate were important factors to affect dry matter yield,which would be the target characters of alfalfa for seasonal utilization.WL-414,Siriver and WL-525HQ showed steady agronomic characters under different environmental conditions and were considered to be the potential alfalfa cultivars for seasonal utilization in southern region.In the mean time.alfalfa forage productivity could be improved by banding the nitrogen and phophorus fertilizer.Addition N300kg/hm2and P2O5300kg/hm2was considered the best.Therefore,selection for less fall dormancy alfalfa cultivars with target characters in conjunction with nitrogen and phophorus fertilizer application could contribute greater biomass in a short-time.