Effect Of Phosphorus Application On Crown Bud Formation And Yield Of Alfalfa

Alfalfa(Medicago Sativa L.),as an good legume forage,has many advantages.For example,the long-term uitilisazion,high grass yield,nutritional richess,good palatability etc.Due to the development of Chinese dairy industry and other industries,the demand for forage grasses has increased gradually,and the development of forage grasshoppers has occupied a important position in China.The shoots of alfalfa is regenerated from the root crown buds,and the number of root crown buds directly determines the amount of grass yield of alfalfa.It is important to explore the mechanism of how root and shoot development and how traits of branches affects the grass yield.In this experiment,in the western part of Jilin Province,different concentrations of phosphorus(P)fertilizer were applied,the growth dynamics of alfalfa cultivar Dongmu No.1 was planted and the traits of root crown buds affected to phosphorus fertilizers were studied.The role of these traits and their impact on yield were analysed,and then the effect of P fertilizer on alfalfa root crown buds,were studied.The main conclusions of this study are as follows:1.Different P concentration had a significant effect on the number of root crown buds in alfalfa.Results show that the application of P can significantly increase the number of root crown buds,and in a certain concentration the number of root buds increased with the P.However,after the P application exceeded 180 kg/hm2,the number of root crown buds did not increase significantly and even showed a declined trend.It indicated that the effect of P on root crown buds was not significant after 180 kg/hm2.The growth dynamics of biomass showed that the number of root crown buds had an increased trend and then decreased after cutting.The root crown buds will grow in a large numbers,however only few grow out of the ground to form branches.Before the the winter,the number of root crown buds of the plants increased significantly to prepare for the regrowth of next year.2.P application significantly increased the yield of alfalfa hay but the difference between the crop yield of second cutting time in the first year and the first cutting time in the second year had significant effects of P application even the difference was not significant between the fertilization treatments in the others cutting periods.However,there is a tendency for the yield to increase with the increase in the amount of P applied.In the first year total grass output,the highest treatment was 225 kg/hm2 P treatment.The highest of the total grass output of the second year was 180 kg/hm2 P treatment.Therefore,the application of P can significantly increase the yield of alfalfa.3.P application had a significant effect on the number of branches of alfalfa,which similar to the results of phosphorus application on root crown buds,whereas a trend of increasing were detected with the increase of P application.From the perspective of yield components,the yield mainly depends on the number of branches,plant height,stem diameter and number of root crown buds.The number of branches was significantly related to the number of root crown buds in the post-castration vegetative period,indicating that the number of root crown buds in the vegetative period had the greatest impact on the yield.P application can significantly increase the number of root crown buds branches and plant yield.