Study On The Effects Of Nitrogen, Phosphorus And Potassium Optimum Fertilization On Export Broccoli Production

Broccoli has become a major export vegetable. In the past few years thecultivating area of broccoli continuously expands and most of them were export,while extensive cultivation management influences the improvement of yield andquality, especially apparent quality which restricts broccoli export.Fertilization is a key factor of influencing the yield and quality of broccoli. At thepresent time, the study about the effects of fertilization on the yield and quality ofbroccoli focuses on fixed ratio of nitrogen, phosphorus and potassium which can'tprovide an exact fertilization amount for broccoli production. Moreover there aredifferent opinions on nitrogen, phosphorus and potassium absorption andaccumulation of broccoli. So discussing the effects of fertilization on yield of broccoli,especially apparent quality is of great value.Using "Shanghai No.4" as experimental material, The effects of differentfertilization on the growth of broccoli, N,P,K absorption and accumulation, yield, Vc,glucosinolates and qualified rate for export wre studied. Using 311-A optimizationregression design of supposed saturation and {3, 2} single grille saturation design, weestablished fertilizer model of nitrogen, phosphorus and potassium, stage fertilizationmodel of nitrogen and confirmed the optimum fertilization proportion by fieldexperiments. The main results were as follows:1. Nitrogen, phosphorus or potassium deficiency which would influence thegrowth and dry yield of broccoli would decrease yield, Vc and qualified rate forexport. Nitrogen and potassium deficiency significantly influenced the yield whichdecreased 17.62%, 15.37% respectively compared to control. The qualified rate ofadding Boron treatment increased significantly.2. The content of N, P and K increased to a different degree along with plantgrowth and more N, P and K accumulated in broccoli during initial stages of bud tocurd form. In the whole growth stages, more than 50% of N, P and K were in leaves. Correlation analysis revealed that the yield significantly correlated with N, Kaccumulation and the qualified rate significantly correlated with the P. They allpositively correlated with nitrogen, phosphorus and potassium content. In the wholegrowth stages, the broccoli absorbed the highest K, and the least N, P. Theaccumulation amount of nitrogen, phosphorus and potassium were 67.5±4.5 mg/g DW,22.1±0.9 mg/g DW and 121.2±7.1 mg/g DW respectively.3. Nitrogen, phosphorus and potassium application amount for maximum yieldwere 371.35kg/hm~2, 102.66kg/hm~2 and 172.04kg/hm~2 respectively. The nitrogen,phosphorus and potassium application amount for 68.59% qualified rate were159.13kg/hm~2, 106.46kg/hm~2 and 160.04kg/hm~2 respectively.4. The effects of different ratio of nitrogen on broccoli in different growth stageshowed that enough basal dressing and appropriate top dressing in the initial stage offlower bud was suitable to improving chlorophyll, net photosynthetic rate and Vc. Thequantities of nitrogen in the initial stage of flower bud significantly influenced totalglucosinolates. The optimum application proportion of nitrogen fertilizer at differentgrowth stages was 0.404:0.265:0.331 and the amount of nitrogen were 121.212kg/hm~2,79.464 kg/hm~2, 99.324kg/hm~2 respectively.