Effects Of Combined Application Of Nitrogen,Phosphorus And Potassium On Production Performance Of Grain Amaranth

In order to obtain the optimum fertilization amount and fertilization ratio of grain amaranth planting in the arid region of central Ningxia,the influence of NPK application on the growth,photosynthetic performance,nutritional quality and yield of grain amaranth was studied by using the"3414" experimental design.The fertilizer effect equation was established to determine the optimal amount of fertilization for grain amaranth planting,aiming at increasing the yield and fertilizer utilization of grain amaranth.The research results are as follows:(1)Nitrogen,phosphorus and potassium fertilizers could promote the increase of plant height,stem diameter and leaf area of grain amaranth in a certain range.The highest treatments of plant height,stem width,leaf area and fresh/dry ratio were N1P1K2,N3P2K2,N2P1K1,N2P1K1 and N2P1K1,respectively.(2)Rational application of NPK fertilizer can increase the chlorophy ll content of grain amaranth,improve photosynthetic performance,and have different effects on chlorophyll fluorescence parameters of grain amaranth.The treatment with the highest chlorophyll content was N2P2K0.The treatments with the highest net photosynthetic rate,stomata]conductance,intercellular CO2 concentration,transpiration rate and leaf water use efficiency were N2P3K2,N2P2K3,N1P1K2,N2P2K3 and N2P2K0,the treatments with the highest FO,Fm,Fv,Fv/Fm and PI were N1P1K2,N3P2K2,N2P1K1,N2P1K1 and N2P1K1,respectively.(3)Rational application of NPK could improve the nutritional quality of the whole plant,and the nutrient quality of grain mites was reduced without fertilization,excessive fertilization and improper application of NPK.Rational application of NPK could improve the nutritional quality of the whole plant,and the nutrient quality of grain mites was reduced without fertilization,excessive fertilization and improper application of fertilizer.Under N3P2K2 treatment,the content of dry matter in grain amaranth was the highest.Under N2P2K2 treatment,crude fat,crude protein and relative feeding value were the highest neutral detergent fiber and acid detergent fiber were the lowest,and the ash content under NOP2K2 treatment was the lowest.(4)The reasonable application of nitrogen,phosphorus and potassium fertilizers could increase the forage yield of grain amaranth.With the increase of fertilization amount,the forage yield of grain amaranth increased first and then decreased.The effect of nitrogen,phosphorus and potassium fertilizer on the forage yield of grain amaranth was N>P>K.The optimum application rates of NPK(pure N,P2O5 and K2O)were 121.05 kg hm-2,100.50 kg hm-2 and 46.35 kg hm-2,respectively,and the optimal fresh grass yield was 90.74 t·hm-2.In this experiment,the fresh grass yield of grain amaranth was the highest under N2P2K2 treatment,reaching 97.73 t·hm-2.(5)The application of NPK fertilizer promoted the increase of seed yield of grain amaranth,and the yield increased first and then decreased with the increase of fertilizer application.Among the yield components,Number of main stem nodes of panicle,1000-grain weight and panicle weight were significantly correlated with seed yield(P<0.01).The optimal application rates of NPK(pure N,P2O5 and K2O)were 112.95 kg·hm-2,89.55 kg·hm-2 and 49.20 kg·hm-2,respectively,and the optimal seed yield was 3081.28 kg·hm-2.In this experiment,the seed yield of grain amaranth was the highest under N2P2K2 treatment,reaching 3415.20 kg·hm-2.In summary,the grain amaranth had the best nutrient composition,the highest grass yield and seed yield under N2P2K2 treatment(N:120 kg·hm-2?P:90 kg·hm2?K:60 kg·hm-2).Through the construction of the fertilizer effect equation for the yield of grass and seed,the optimal fertilization amount of grain amaranth was established in the arid area of central Ningxia.