Effect Of Fertilization Combination Of Nitrogen,Phosphorus,and Potassium On Yield And Quality Of Pueraria Thomsonii

As a cash crop with the same origin of medicine and food,pueraria thomsonii has a good value in development and utilization and has been widely welcomed at home and abroad in recent years.However,at present,there are unreasonable phenomena of fertilization,misproportion distribution of nitrogen,phosphorus and potassium in the soil,and serious problems of regional soil acidification,which leads to insufficient nutrient supply of the soil for the growth and development of pueraria thomsonii.Therefore,it is of great significance to study the rational application of NPK to guide the cultivation of pueraria thomsonii.To explore suitable planting pueraria thomsonii fertilization scheme,the selection test"GUI FENGE NO.1"as the experimental material,adopts the method of"3414"application design,research on the pueraria thomsonii NPK with growth,photosynthetic characteristics,dry matter content,NPK absorption law and production quality,the influence of applied through the establishment of equations,synthetically considering the indicators of NPK with pueraria thomsonii well.The main research results are as follows:1.The application of NPK can promote the growth and development of rhizome,increase the content of chlorophyll in leaves,and promote the expansion and elongation of storage roots.From the storage root formation stage to the maturity stage,the fertilization level N₂P₂has the greatest influence on root length and root thickness,and N₃level is not conducive to the formation of underground storage roots.The stem and root thicknesses increased with the increase of nitrogen and phosphate fertilizer and then decreased with the increase of potash fertilizer.During the growth period of storage roots,when the other two fertilizers were kept at the level of 2,the root roughness increased first and then decreased with the increase of nitrogen and potassium fertilizer,and then decreased first and then increased with the increase of phosphate fertilizer,the maximum value increased by 9.57%,16.83%and 37.62%,respectively.With the increase of nitrogen,phosphorus and potassium fertilizer,the root length decreased at first and then increased,and the maximum value increased by28.63%,49.92%and 40.91%respectively compared with the control group without fertilization.Application of phosphate fertilizer can improve the photosynthetic indexes of the leaves of pueraria thomsonii,while application of potassium fertilizer can increase the content of chlorophyll in the leaves,stomatal conductance and intercellular CO₂concentration.Comprehensive consideration,under the fertilization level of N₂P₂K₂,the growth trend of pueraria thomsonii was better.2.The absorption and accumulation of nitrogen,phosphorus and potassium in pueraria thomsonii showed an"S"pattern.The root nitrogen content of the fertilization level of N₁in seedling stage was the highest.The nitrogen content in leaf of pueraria thomsonii at different stages was higher than that of stem and storage root,after storage roots formation,the nitrogen content showed as leaf>stem>root.After the storage roots began to expand,the influence of nitrogen application level on nitrogen absorption and accumulation was as follows:N₁>N₂>N₀>N₃.The influence of phosphorus application level on phosphorus absorption accumulation was as follows:P₂>P₃>P₁>P₀,P₀was the best at the maturity stage.Potassium level K₂was the best to promote potassium absorption in pueraria thomsonii.The formation of storage roots of pueraria thomsonii needs a lot of nitrogen and phosphorus,and the demand of nitrogen and phosphorus is reduced in the later stage.3.During the whole growth period,the distribution of dry matter in the aboveground part of the plant was continuously transferred to the storage roots.The yield and starch content were also higher when the content and proportion of dry matter were larger.The distribution ratio of root dry matter in seedling stage was 13.54%～31.05%,and the distribution ratio of overground part was68.95%～86.46%.In the mature stage,the distribution ratio of root dry matter increased to 67.53%～79.61%,and that of overground part decreased to18.89%～32.47%.4.The yield and quality of pueraria thomsonii could be improved by NPK combination.The improvement effect of each nitrogen application level on the content of tuberous starch and protein was N1>N2>N3,and the improvement effect of potassium application levels K₁and K₂was better.Nitrogen application level N₁and N₂can increase the content of puerarin in storage roots,while nitrogen application level N₃can inhibit the synthesis and accumulation of puerarin.Fertilization levels of N₂,N₁and P₃had the most obvious promoting effect on the increase of soluble sugar content in storage roots.Under the conditions of this experiment,the fresh weight and yield per plant of fertilization level N₂P₂K₂were the highest,and the aboveground part and storage root grew well.The optimal fertilizer application rates were calculated as follows:pure nitrogen 398.22 kg/hm²,pure P₂O₅483.87 kg/hm²and pure K₂O 393.57 kg/hm².The optimum yields were 39661.10 kg/hm²,39006.72 kg/hm²and 39709.82kg/hm²,respectively.