Effects of potassium fertilizer rates on biomass,yield and nutrients absorption and utilization of oilseed rape in the middle reaches of the Yangtze River
Field experiments were conducted to investigate the effects of different application rates of potassi-um chloride(KCl)on biomass,seed yield,and nutrient accumulation and distribution in oilseed rape at both the seedling and maturity stages.The study was carried out in Jiangxia District,Wuhan City,Hubei Province,located in the middle reaches of the Yangtze River from 2021 to 2022.This research aims to provide a theoretical foundation for the optimal application of potassium(K)fertilizer in oilseed rape cultivation.Six treatments were applied,in-cluding K0(K2O 0 kg/hm2),K30(K2O 30 kg/hm2),K60(K2O 60 kg/hm2),K90(K2O 90 kg/hm2),K120(K2O 120 kg/hm2)and K150(K2O 150 kg/hm2).The results indicated that the biomass of all oilseed rape organs at both seedling and maturity stages,as well as seed yield,significantly increased within a certain range of increasing levels of K fer-tilizer.The maximum increase in seed yield was observed to be up to 1199.6 kg/hm2 with an increase ratio of up to 57.20％.When the application rate of K exceeded 120 kg/hm2,there was no significant increase in shoot biomass and seed yield.With increasing K fertilizer application,there was a significant increase in K content across all or-gans.However,N content did not show significant changes at both the seedling and maturity stages.Notably,P con-tent in seeds at the maturity stage exhibited a significant increase.The partial factor productivity of K fertilizer sig-nificantly decreased with increasing K fertilizer application.However,the agronomic efficiency,physiological effi-ciency,apparent recovery efficiency and harvest index of K fertilizer all reached their maximum at an application rate of 90 kg/hm2.Subsequently,these efficiencies gradually decreased with further increases in K fertilizer.Eco-nomic analysis revealed that the output-input ratio and net income were optimized at a K application rate of 120 kg/hm2.Further increases in K fertilizer would lead to reduced economic efficiency.In addition,the optimal application rate of K fertilizer for maximizing economic efficiency in this region is determined to be 114.6 kg/hm2 based on a combination of linear and platform fitting results.Consequently,rational utilization of K fertilizer can significantly enhance shoot biomass and promote the accumulation of essential nutrients(N,P,and K),thereby resulting in in-creased plant height,primary branch count,pod number,and ultimately achieving higher yields while ensuring max-imum economic efficiency.
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