The effect of nitrogen and phosphorus fertilizer combined application on the yield and nutrition value in vegetative growth and reproductive growth stages of local Elymus sibiricus
To explore the effect of nitrogen and phosphorus fertilizer combined application during the critical period of vegetative and reproductive growth on the production of native Elymus sibiricus in alpine region,design different nitrogen and phosphorus fertilizer combinations during the tillering to elongation stage and heading to flowering stage,observe the effects of different fertilization combinations on tillering,grass yield,dynamic change of grass yield,ratio of stem to leaf,nutrient content,total digestible nutrient(TDN),relative feeding value(RFV),and quality grading index of forage(GI),provide a reasonable combined fertilization scheme and Reference for the high yield of native Elymus sibiricus in alpine region.The results showed that,topdressing with urea or diammonium phosphate could promote tillering of Elymus sibiricus during the tillering to elongation stage and heading to flowering stage,and the effect was better in the early stage.During the elongation to heading stages,the growth of Elymus sibiricus was the fastest,with the largest increment of grass yield,the dry matter accumulation of each fertilization combination reached 39％to 44％during this period.The grass yield and grass yield increment in group V,I,and Ⅱ increased significantly in both 2-year-old and 3-year-old Elymus sibiricus,the yield of fresh grass increased by 1759.59,1707.16,1148.38 kg/hm2 in group Ⅴ,Ⅰ,and Ⅱ of 2-year-old Elymus sibiricus,which increased by 1769.14,1755.81,1100.08,901.13 kg/hm2 in groups Ⅴ,Ⅰ,Ⅳ and Ⅱ of 3-year-old Elymus sibiricus,respectively.Topdressing Urea and DAP could reduce the stem-leaf ratio and improve the grass quality,while the effect of SSP was less.The CP content,TDN and RFV values of local Elymus sibiricus were increased,the NDF and ADF contents were decreased,and the grass quality and nutritional value were improved to varying degrees in groups Ⅴ,Ⅰ,Ⅱ and Ⅳ.According to GI,the forage of each fertilization combination was divided into three grades:group Ⅰ(2.34)and group Ⅴ(2.06),group Ⅱ(1.85)and group IV(1.87),group Ⅲ(1.59)and group VI(1.42).In conclusion,the application of Urea or DAP during the tillering to jointing stage and the heading to flowering stage could promote the tillering of Elymus sibiricus.The fertilization combination of DAP+DAP(group Ⅴ),Urea+Urea(group Ⅰ),and Urea+SSP(group Ⅱ)could increase the fresh and dry grass yield,CP content,TDN,RFV,and GI values of 2-year-old and 3-year-old Elymus sibiricus,reduce the content of NDF and ADF,and improve its forage quality and nutritional value.
native elymus sibiricusvegetative growth and reproductive growthnitrogen and phosphorus fertilization combinationgrass yieldnutrient contenttotal digestible nutrientrelative feeding valuequality grading index of forage
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