| Nitrogen(N), phosphorus(P), potassium(K) are three major nutrient elements for the growth of crops, and the three elements have important effect on growth,development,yield and quality of crops.In this study, the starch-type sweet potato variety(yushu 17) is be chosen, by three factors quadratic regression orthogonal rotational combination design, to research the effects under different NPK configuration on growth of vine,photosynthesis and ability of distribution and transport,and nutrient uptake of sweet potato, and build mathematical regression model, select optimized scheme.The main results of the study are as follows:1. Potash has the greatest influence on the growth of sweet potato in medium-potassium and high-nitrogen soil(Youyang), with the increase of potash, stem diameter, vine length, LAI,dry matter accumulation and R/T increase significantly, with the increase of nitrogen, stem diameter, vine length, LAI and R/T increase significantly, with the increase of phosphate, vine length firstly increases then decreases.And nitrogen is the chiefly factor to affect the growth of sweet potato in high-potassium and low-nitrogen soil(Caoshang),with the increase of nitrogen or phosphate, stem diameter, vine length, LAI,dry matter accumulation and R/T increase significantly, with the increase of potash, LAI and R/T increase significantly.2. Potash has the greatest influence on the accumulations of N,P and K in medium-potassium and high-nitrogen soil(Youyang),with the increase of potash the accumulations of N,P and K increase significantly,with the increase of nitrogen, the accumulation of N increases significantly,and the interaction effect of nitrogen and potash on N accumulation reaches significant level.And the effects of nitrogen and phosphate on the accumulation of N,P and K reach significant level in high-potassium and low-nitrogen soil(Caoshang),and the effect of nitrogen is bigger.With the increase of nitrogen, the accumulations of N,P and K increase,with the increase of phosphate,N and P accumulations increase,K accumulation first increases then decreases.And the interaction effect of phosphate and potash on P accumulation and the interaction effect of nitrogen and phosphate on K accumulation both reach significant level.3.The effects of three fertilizers on chlorophyll content of sweet potato in medium-potassium and high-nitrogen soil(Youyang) and high-potassium and low-nitrogen soil(Caoshang) are as follows: nitrogen>potash>phosphate, and chlorophyll content significantly increases with the increase of nitrogen and potash.In medium-potassium and high-nitrogen soil(Youyang), potash has the largest effect on Pn, Gs, Tr and Ci.And Pn, Gs, Tr significantly increase with the increase of nitrogen and potash, but Ci significantly reduces with the increase of nitrogen and potash.In high-potassium and low-nitrogen soil(Caoshang), nitrogen has the largest effect on Pn, Gs, Tr and Ci.And Pn, Gs, Tr significantly increase with the increase of nitrogen and phosphate, Pn significantly increases with the increase of potash,Gs and Tr significantly first decrease then increase with the increase of potash,and Ci significantly decreases with the increase of nitrogen and phosphate. At the same time,the interaction effect of nitrogen and potash,and the interaction effect of phosphate and potash on Pn reach significant level.4.The effects of the three fertilizers on SPS activity have not been reached significant level in medium-potassium and high-nitrogen soil(Youyang) and high-potassium and low-nitrogen soil(Caoshang).In medium-potassium and high-nitrogen soil(Youyang), starch content decreases with the increase of potash, and firstly increases then decreases with the increase of nitrogen, the effects of two fertilizers both are significant and potash fertilizer has the bigger influence;in high-potassium and low-nitrogen soil(Caoshang), starch content declines significantly with the increase of nitrogen and phosphate, and the effect of nitrogen is larger, at the same time,the interaction effect of nitrogen and potash is significantly negative.In medium-potassium and high-nitrogen soil(Youyang),the total sugar content increases with the increase of nitrogen or potash,and firstly increases then decreases with the increase of phosphate,and the effect of potash is the biggest;in high-potassium and low-nitrogen soil(Caoshang),the total sugar content increases with the increase of nitrogen,phosphate, or potash, and the effect of nitrogen is the largest, and the interaction effect of phosphate and potash has reached significantly positive level.5. The effects of three fertilizers on fresh potato yield, biological yield in medium-potassium and high-nitrogen soil(Youyang) are as follows: potash>nitrogen>phosphate, and with the increase of nitrogen or potash, fresh potato yield and biological yield increase significantly;the effects of three fertilizers on fresh potato yield, biological yield in high-potassium and low-nitrogen soil(Caoshang) are as follows: nitrogen>phosphate> potash, and in addition to the effect of potash on biological yield has not reached significant level, others are significant, then nitrogen and potash,phosphate and potash have significantly positive interaction effect on fresh potato yield.In different soil, the effect of NPK fertilizer on yield of sweet potato is different, in medium-potassium and high-nitrogen soil(Youyang) the influence of potash is biggest, in high-potassium and low-nitrogen soil(Caoshang) the influence of nitrogen is biggest.6. The fresh potato yield is significantly positive correlation with total sugar content, Pn, chlorophyll,N accumulation, P accumulation,K accumulation,R/T and LAI, significantly negative correlation with starch content in medium-potassium and high-nitrogen soil(Youyang) and high-potassium and low-nitrogen soil(Caoshang), and there is no significant correlation between fresh potato yield and biological yield in medium-potassium and high-nitrogen soil(Youyang), but fresh potato yield and biological yield have very significantly positive correlation in high-potassium and low-nitrogen soil(Caoshang);starch content has significantly negative correlation with total soluble sugar, and has no significant correlation with SPS activity in medium-potassium and high-nitrogen soil(Youyang) and high-potassium and low-nitrogen soil(Caoshang).7. The fresh potato yield has the equation with the three fertilizers in medium-potassium and high-nitrogen soil(Youyang): Y=2197.29+76.42X1+76.42X3-90.16X2^2.And the equation of the fresh potato production with the three fertilizers satisfies in high-potassium and low-nitrogen soil(Caoshang):Y=2624.48+149.00X1+92.01X2+68.09X3+84.74X1X3+99.27X2X3.In order to get the best fresh potato production and soluble total sugar content in medium-potassium and high-nitrogen soil(Youyang),the optimal scheme is as follows: nitrogen 9.57 ~ 11.10 kg/667 m2, phosphate 6.75 ~ 7.00 kg / 667 m2, potash 19.60 ~ 21.30 kg / 667 m2, the ratio of the three fertilizers is 1.50:1:2.97;in order to get the best fresh potato production and soluble total sugar content in high-potassium and low-nitrogen soil(Caoshang),the optimal scheme is as follows: nitrogen11.22~12.48 kg/667 m2, phosphate 7.63~8.88 kg / 667 m2, potash 15.00~20.65 kg / 667 m2, the ratio of the three fertilizers is 1.43:1:2.16. |
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