Effects Of Reducing Fertilizers On Growth,Yield And Fertilizer Use Efficiency Of Direct-seeded Hybrid Rice After Wheat

In order to study the effects of reduced fertilization on the growth and development,economic traits and fertilizer use efficiency of direct seeding wheat hybrid rice in the northeastern,provide scientific basis for reasonable fertilization of direct-growing rice.Field trials of 28 hybrid rice varieties mainly promoted in Sichuan.Using Jin Zhengda 3+rice special compound fertilizer,its nutrient content is N?26%?+P₂O₅?10%?+K₂O?15%?.Sichuan-based seasonal arid region,in contrast to the level of local farmers'habitual fertilization,T₁-45kg/667m²,set three kinds of reduced fertilization treatment,T₂-45kg/667m²,T₃-31.5kg/667m²,T₄-18kg/667m²and 0kg/667m².28 hybrid rice varieties were used as experimental materials for field experiment,Comparing their differences ingrowth,development,economic traits,yield levels and fertilizer use efficiency at different fertilization levels.The main results are as follows:1.Reduced fertilization has a certain effect on the whole growth period,sowing-extraction period and pumping-maturity period of the tested varieties.Compared with the T₁ treatment,The mean sowing-draw period of T2 treatment was shortened by 3 days,the average pumping-maturity period was prolonged by 3 days,and there was no significant change in the whole growth period.The average sowing-draw period of the tested varieties under T3 treatment was shortened by 3 days.The mean value was prolonged by 1 day,and the whole growth period was shortened by2 days.The average sowing-drawing period of the tested varieties under T4 treatment was shortened by 2 days,the average pumping-maturation period was shortened by 1day,and the whole growth period was shortened by 3 days.2.The rate of stem pod growth under different fertilization treatments was T₁>T₂>T₃>T₄.The growth trend of stem pods among different cultivars was somewhat different.3.Reduced fertilization has a certain influence on the upper leaves of the tested varieties.Compared with T₁ treated leaf indexes,T₂ treatment decreased but did not reach significant levels.The area of the inverted two-leaf leaves and the inverted three-leaf were significantly smaller under T₃ treatment.T₄ treatment significantly decreased the length of the flag leaf and the length of the inverted trifoliate leaf.4.The reduced fertilization had certain effects on the yield traits of the tested cultivars.Compared with the yield traits under T₁ treatment,the number of effective panicles,grains,filled grains and panicle weight under T₂ treatment were reduced by3.74%,2.16%,1.42%and 1.09%,respectively;the seed setting rate and 1000-grain weight were increased by 0.84%and 0.47%.Under the treatment of T₃,the number of effective panicles,grains,filled grains and panicle weight decreased by 8.96%,8.77%,6.78%and 6.51%,respectively.The seed setting rate and 1000-grain weight increased by 2.18%and 0.49%,respectively.Under T₄ treatment,the number of effective panicles,grains,filled grains,1000-grain weight and panicle weight decreased by 17.84%,12.09%,8.74%,1.46%,and 10.16%,respectively;the seed setting rate increased by3.83%.5.Compared with T₁,the average yield of the tested varieties under T₂ decreased by4.75%,T₃ decreased by 14.74%,and T4 decreased by 26.22%.The response of different rice varieties to reduced fertilization showed a large difference.Compared with T₁,the yields of three varieties increased significantly under the T₂,it is Qyou28,Luxiangyou177 and Fuyou6688.There were 9 varieties was basically the same as that of T₁;the yield of 16 varieties was significantly reduced,among which Dexiangyou 146had the largest decrease of 19.1%.Under the T₃ treatment,the yields of Qyou 28 and Fuyou 6688 increased,but the difference was not significant.There were 6 varieties with basically the same yield as T₁,and 22 varieties had a significant decrease,with a decrease of 8.36%-30.43%.Under the T₄ treatment,the yield drop of the tested varieties ranged from 11.76%to 39.77%.Among them,there were 7 varieties with a decline of less than 20%,13 varieties with a decrease of 20-30%,and 8 varieties with a decrease of more than 30%..6.Under different fertilization treatments,the correlations between yield and yield traits of the tested cultivars were basically the same.Under T₁ treatment,the yield was significantly positively correlated with effective panicles,1000-grain weight and single panicle weight.The correlation was single panicle weight>1000-grain weight>effective panicle,and yield was negatively correlated with seed setting rate.Under T₂ treatment,yield was significantly correlated with effective panicles and 1000-grain weight and negatively correlated with seed setting rate.There was a positive correlation between yield and yield traits under T₃ treatment,and the correlation between yield and effective panicles and 1000-grain weight reached a significant level.There was a significant positive correlation between yield and effective panicle,1000-grain weight and single ear weight under T₄ treatment.The correlation was between single panicle weight>effective panicle>1000-grain weight and negative correlation with seed setting rate.7.Under different reduced fertilization treatments,the nitrogen utilization rate of the tested varieties increased slightly,and the contribution rate of nitrogen fertilizer decreased with the decrease of fertilizer application.The partial productivity of nitrogen fertilizer increased with the decrease of fertilizer application amount.The utilization rate of phosphorus fertilizer increased with the amount of fertilizer application;the contribution rate of phosphorus fertilizer showed a downward trend with the decrease of fertilizer application amount;the partial productivity of phosphorus fertilizer increased with the decrease of fertilizer application amount.With the decrease of fertilization,the agrochemical utilization of potash showed a trend of increasing first and then decreasing.The contribution rate of potash fertilizer decreased with the decrease of fertilization.The partial potash fertilizer productivity decreased with the decrease of fertilization.