Effect Of Different Phosphorus Fertilizer Treatments On The Growth And Development And Seed Yield Of Seed-Making Alfalfa

In order to investigate the effect of phosphorus fertilization on the growth and seed yield of alfalfa,this study was conducted in a field experiment using Medicago sativa as the test material and five phosphorus fertilization gradients(0(P0),75(P1),150(P2),225(P3),300(P4)kg/hm~2)were set.(P4)kg/hm~2),and measured root traits,plant height,growth rate,dry matter accumulation in various organs,phosphorus uptake,seed yield components and seed yield at different growth stages of alfalfa to determine the optimum phosphorus requirement of alfalfa and its uptake pattern.The results of the study can provide scientific assistance in determining the optimum phosphorus application for alfalfa seed production in the Northwest Rangeland and in solving seed production problems.The results of the study are as follows.(1)Effect of different phosphorus fertiliser treatments on alfalfa root characteristics.The total root length,root surface area,average root diameter and root volume of alfalfa at different fertility periods increased significantly with the application of phosphorus fertiliser and reached a maximum at P2 treatment in all fertility periods.(2)Effects of different phosphorus fertiliser treatments on alfalfa growth and development.The plant height and growth rate of alfalfa at different fertility periods were significantly promoted by the application of phosphorus fertiliser,with a maximum plant height of 80.00cm and a maximum growth rate of 1.55cm/day.(2)Effect of different phosphorus fertilizer treatments on dry matter accumulation and root to crown ratio of alfalfa.The above-ground biomass of various nutrients and reproductive organs,the below-ground biomass and the root-tube ratio of alfalfa at different fertility periods all increased significantly under the application of phosphorus fertiliser,all reaching a maximum under the P2 treatment.(3)Effect of different phosphorus fertiliser treatments on nutrient uptake and utilisation in alfalfa.The phosphorus uptake in above-ground reproductive organs and phosphorus uptake in the lower part of the ground of alfalfa at different fertility periods showed a trend of first increasing and then decreasing under the application of phosphorus fertilizer,and both reached the maximum under the P2 treatment.(4)Effect of different phosphorus fertiliser treatments on the components of alfalfa seed yield and yield.The seed yield components of alfalfa at different fertility periods:effective number of branches per plant,number of inflorescences per plant,number of florets per inflorescence,number of pods per plant,number of seeds per pod and thousand seed weight all reached the maximum at P2 treatment,and the yield increase effect was most obvious at this time,reaching the maximum value of 263.95 kg/hm~2.In summary,all growth indicators reached their maximum values at the P2 treatment,and there was also a significant promotion effect on seed yield.Therefore,the optimum phosphorus application rate for increasing alfalfa yield was 150 kg/hm~2 in this experiment.