Study On The Interaction Between Ammonium And Potassium Absorption In Rice

Nitrogen and potassium are the two essential nutrients for rice growth and play an irreplaceable role in rice development.Prior study proved there are interactions between plant nitrogen and potassium absorption.In rice production,many have been done on fertilization,grain yield,and fertilizer use efficiency.However,most of the studies have been focused on the effects of single fertilizer.Although studies have shown that the combination of nitrogen and potassium fertilizers can significantly increase crop yields,this interaction between fertilizers has not been studied in detail.Therefore,in order to explore the interaction of ammonium and potassium absorption and deepen the rice nutrient absorption theory,it is necessary to analyze the nutrient absorption and utilization from the view of ammonium and potassium interaction,which may provide a new perspective for the study of nitrogen fertilizer use efficiency in rice.In this study,the high nitrogen use efficiency（QL）and the low inefficiency rice variety（HK3）,which were selected in the previous period,were subjected to hydroponic tests according to the method of IRRI,studied the interactions between ammonium and potassium absorption in roots,the effects of ammonium and potassium concentrations on rice seedling growth,and the transmembrane transport of NH₄⁺and K⁺in rice roots under different concentrations.A field experiment was carried out to study the effects of increasing application of potassium fertilizer on rice growth and nitrogen utilization ratio under high nitrogen fertilizer.Research indicates:1.when K⁺concentration was less than 0.2 mM,the K⁺uptake curve through HATS in rice root could be described by Michaelich-Menten equation.NH₄⁺decreased K⁺uptake rate,the V_max of K⁺kept decreasing with the increase of NH₄⁺concentration,however,the effect of NH₄⁺on K_m was relatively little.Compared with without NH₄⁺,the V_max and K_m of K⁺uptake at the 1.62 mM NH₄⁺application was decreased by 47.30%and 12.33%in rice variety QL,and by 39.21%and16.46%in rice variety HK3,respectively.When K⁺was higher than 0.5 mM,K⁺was mainly absorbed through LATS,in which the uptake rate of K⁺was kept increasing with the increase of K⁺concentration,and NH₄⁺greatly decreased the uptake rate of K⁺-LATS at the same concentration of K⁺.The uptake rate of NH₄⁺was increased with the increase of NH₄⁺concentration,however,no significant difference was observed in NH₄⁺uptake rate under different concentration of K⁺.2.Under the three level of NH₄⁺treatments,the net absorption rate in meristematic zone of the two rice varieties was 1.62 NH₄⁺>0.4 NH₄⁺>6.48 NH₄⁺,Under medium NH₄⁺level,the net inflows in QL and HK3 were1.35,2.84 times and 1.1,2.4 times that of NH₄⁺low and high treatments treatments.In the elongation zone,there was a efflux phenomenon in the high NH₄⁺treatment.Under the three level of K⁺treatments,The K⁺net absorption rate of the QL and HK3 increased with the increasing of K⁺concentration in meristematic zone and elongation zone.Under the three different K⁺treatments,the average K⁺net absorption rate of QL and HK3 under medium NH₄⁺treatment was the highest,In the high NH₄⁺concentration,there was a certain efflux in the root system meristem K⁺,but the increase in K⁺concentration in the high NH₄⁺could significantly reduce the K⁺efflux rate in the meristem of root.3.The increasing of K⁺concentration under low NH₄⁺treatment promoted the growth of rice root system,and the root biomass of 2 rice varieties are all increased.Under the medium NH₄⁺treatment,the positive interaction between medium K⁺and NH₄⁺had the greatest influence on the growth of QL roots,and the total root length,root surface area,total root volume,and root tip number under medium K⁺were 7.82%,12.8%,14.7%,and 12.0%larger than those of low K⁺,respectively.For HK3,increasing K⁺promoted the root growth,and the root volume increased significantly.High K⁺and medium K⁺were 17.7%and 12.8%higher than that of the low K⁺,respectively.The increase of K⁺concentration under high NH₄⁺treatment significantly promoted the growth of roots of the two rice varieties.There was no significant difference between medium K⁺and high K⁺,but the both were significantly greater than low K⁺.The total root length,root surface area,total root volume,and root under medium K⁺treatment of HK3 were 19.5%,13.3%,8.6%,and 6.1%higher than low K⁺,respectively;increasing K⁺concentration under the three different concentrations of NH₄⁺promoted the root activity,respiratory intensity,and Rubp enzyme activity of QL and HK3.The accumulation of N and K in the two rice cultivars were increased.The increase of K⁺concentration under the certain NH₄⁺concentrations also increased the leaf area,the dry weight of the plants,and then enhanced photosynthetic activity.4.The increasing of potassium fertilizer application under high-N fertilizer enhanced several physiological indicators,such as the number of tillers、leaf area index and dry matter weight during multiple growth stages of plants.For example,the number of tillers of QL and HK3 increased by 7.8%and 7.2%,respectively.the leaf area index during the tillering stages were increased by 17.3%、19.9%,and the dry weight of plant at maturity were increased by 22.0%and 26.5%,respectively,and then the plant yield of QL and HK3 were all increased by 25%.The accumulation of N and K and the utilization efficiency of N fertilizer in different growth periods all increased.For example,at the full heading stage,N、K accumulations of QL and HK3 increased by 5.3%,9.9%and 33.0%、27.5%,respectively.The utilization rate of N fertilizer agronomy increased by 91.11%and 103.31%.The results show that increasing K fertilizer under high-N fertilizer can promote plant growth,reduce the toxicity of high NH₄⁺and improve the utilization efficiency of N fertilizer.