Study On The Effect Of Different Nitrogen And Potassium Treatments On Wheat Growth And Potassium Diagnosis Index

Wheat is one of the four major grain crops in China,and its yield accounts for about1/4 of the total grain output in China.Planting wheat with high yield and high efficiency and maintaining the steady increase of yield can effectively solve the food security problem faced by China.Fertilization contributed about 50%to the increase of grain yield and about30%to the total grain yield.China is mainly faced with the problem that the price of international potash fertilizer remains high all the year round.The realization of high wheat yield and efficient utilization of fertilizer is the main contradiction that needs to be solved urgently in wheat production.The study on the effects of N,K and N-K interaction on wheat growth can provide technical support for the accurate management of K in wheat.This paper firstly systematically analyzed the dynamic changes of wheat growth indexes,agronomic parameters,canopy spectrum and soil potassium content with different growth stages under different nitrogen and potassium fertilizer gradient,and clarified the effects of N,K and N-K interaction on the growth stages.The results showed that nitrogen had the greatest effect on wheat growth,followed by potassium,and the N-K interaction was the last.Nitrogen had positive effects on PNC,PKA,PNA,AGB,LAI and NDVI;nitrogen had negative effects on the K/N value of leaves and the CI_{red edge};it had no significant effect on K/N value of plant.K had positive effects on PKC,PKA,AGB,plant K/N value,leaf K/N value,K sensitive spectral index(R₆₁₀-R₅₁₀)/(R₆₁₀+R₅₁₀-2×R₄₃₅)and(R₁₇₀₅-R₁₃₈₅)/(R₁₇₀₅+R₁₃₈₅-2×R₇₀₄),soil available K and slow available K contents;it showed negative effect on PNC.At low K level,K had positive effects on PNA,LAI and NDVI,while at high K level,K had negative effects.N-K interaction had positive effects on PNA and AGB;it had negative effects on PNC,PKC,PKA and K/N values of leaves;and no significant effects on K/N value of plants and LAI.Further explore the different gradient of nitrogen and potassium treatment on wheat yield and yield components,the influence of the different development stages of the analyzed effect of wheat growth indexes of wheat grain yield,and studied the quantitative relation of different potassium index and relative production,put forward by using the method of production grade potassium diagnosis index,determined the different potassium diagnosis indexes in different growth period of the threshold.The results showed that both N and K were positively correlated with yield in a certain range,but the N-K interaction effect o on yield was not significant.The effect of nitrogen on yield was greater than that of potassium.Nitrogen mainly affected the spike numbers and grains per ear,while potassium mainly affected the spike numbers.PKC,PKA,PNC,PNA,AGB,LAI and canopy spectral index were significantly correlated with yield in some growth stages.PKC,PKA,K sensitive spectral index 1 and K sensitive spectral index 2 can all be used as wheat potassium diagnostic indexes,PKA is better than PKC,K sensitive spectral index 2 is better than K sensitive spectral index 1.The middle stage of grain filling is the best time for wheat potassium diagnosis.Relative PKA as a potassium diagnostic index can eliminate the influence caused by different growth stages.The thresholds of different potassium diagnostic indexes were established according to different degrees of potassium deficiency in wheat.Taking the relative PKA,which was not affected by the growth period,as an example,when the relative PKA was lower than 0.89,potassium supplementation should be made in time to avoid wheat yield loss caused by potassium deficiency.The results of this study will provide theoretical basis and technical support for real-time diagnosis of wheat potassium nutrition.