| In this study,early rice tanliangyou 215 and late rice Taiyou 390 were used as experimental materials to study the balanced fertilization technology of double cropping rice.The nitrogen application rate was set at three levels(N1,N2 and N3),and the early rice was112.5,150 and 187.5kg/hm~2respectively;Late rice was 150,187.5 and 225 kg/hm~2respectively;Three levels(F1,F2 and F3)were set as fertilization methods.F1 was the base fertilizer:tiller fertilizer=5:5,F2 was the base fertilizer:tiller fertilizer:panicle fertilizer=4:3:3,F3 was the base fertilizer:tiller fertilizer:panicle fertilizer:grain fertilizer=4:3:2:1,and another no nitrogen treatment(N0)was set as the control(CK).The growth and agronomic characters,yield,key enzyme activities of nitrogen metabolism and nitrogen use efficiency of rice were studied.The main results are as follows:(1)Nitrogen application rate and fertilization method had significant effects on Tillering capacity,leaf area index,Leaf SPAD value and dry matter accumulation of double cropping rice.The number of tillers in early rice N3F1 was the largest,532.73/㎡,followed by526.93/㎡in N3F2 treatment.The number of tillers of late rice N3F3 is the most,468.12/㎡.The leaf area index of early and late rice showed an upward trend with the increase of nitrogen application.The treatment of medium and high nitrogen N2 and N3 was significantly higher than that of low nitrogen N1,and there was no significant difference between N2 and N3.The SPAD value of early and late rice leaves increased with the increase of nitrogen application.The middle and high nitrogen N2 and N3 treatments were significantly higher than the low nitrogen N1 treatment,and there was no significant difference between N2 and N3 treatments.The dry matter accumulation per plant of early and late rice showed an upward trend with the increase of nitrogen application.The medium and high nitrogen N2 and N3 treatments were significantly higher than the low nitrogen N1treatment,and there was no significant difference between N2 and N3 treatments.High nitrogen N3 treatment of early rice was higher than other treatments in full tillering stage,booting stage,full heading stage,filling stage and mature stage,which were 14.80%～144.69%,6.94%～85.91%,8.31%～64.14%,3.39%～60.46%and 3.80%～47.51%respectively.High nitrogen N3 treatment of late rice was higher than other treatments in full tillering stage,booting stage,full heading stage,filling stage and mature stage,which were28.94%～338.7%,33.67%～187.37%,11.86%～73.81%,17.72%～73.56%and 15.77%～64.86%respectively.(2)The amount of nitrogen application and the method of fertilization had significant effects on the yield and yield components of double cropping rice.In terms of nitrogen application rate,the number of effective panicles of high nitrogen N2 and N3 treatment in early rice was higher than that of low nitrogen N1 treatment,and N3 treatment was higher than other treatments,6.85%and 61.68%higher.The number of grains per panicle showed the trend of N3>N2>N1,but the difference was not significant.The seed setting rate decreased with the increase of nitrogen application.There was no significant difference in1000 grain weight among treatments.The theoretical yield and actual yield of high nitrogen N3 treatment were higher than CK,N1 and N2 treatment.The theoretical yield was higher by 52.5%,15.87%,4.27%and the actual yield was higher by 52.77%,16.49%and 4.82%respectively.There was no significant difference in yield between medium and high nitrogen N2 and N3 treatment,but they were significantly higher than low nitrogen N1 treatment.The number of effective panicles of high nitrogen N2 and N3 treatment in late rice was higher than that of low nitrogen N1 treatment,17.08%and 20.41%respectively.The number of grains per panicle showed the trend of N3>N2>N1.N2 and N3 treatments were significantly higher than N1 treatments.The seed setting rate decreased with the increase of nitrogen application.The theoretical yield and actual yield of N3 treatment were higher than CK,N1 and N2 treatment,the theoretical yield was57.37%,17.50%and 2.42%higher respectively,and the actual yield was 59.78%,19.72%and 2.70%higher respectively.The yield difference between medium and high nitrogen N2 and N3 treatment was not significant,but they were significantly higher than low nitrogen N1 treatment.(3)Nitrogen application rate and fertilization method had significant effects on the activities of key enzymes of nitrogen metabolism in double cropping rice.In the whole growth period of rice,the nitrate reductase activity of early and late rice was the highest at booting stage;The enzyme activity increased with the increase of nitrogen application.Nitrate reductase was the highest in high nitrogen N3F1 treatment at the peak of tillering,followed by medium nitrogen N2F1 treatment.At booting stage and full heading stage,the treatment of medium and high nitrogen N2 and N3 was higher than that of low nitrogen N1.The enzyme activity decreased gradually during grain filling,and there was no significant difference between low,medium and high nitrogen treatments.In the whole growth period of rice,the activity of glutamine synthase in early and late rice was the highest at full heading stage and the lowest at grain filling stage.Early rice N3F1 treatment was the highest at the peak tillering stage,followed by medium nitrogen N2F1 and N2F2 treatment.There was no significant difference between treatments at booting stage and full heading stage.During the grouting period,the treatment of medium and high N2 and N3 was higher than that of low nitrogen N1.The late rice N3F1 treatment was the highest at the peak tillering stage,followed by N3F2 and N3F3 treatments.Medium and high nitrogen N2 and N3 treatments were higher than low nitrogen N1 treatments at booting stage and full heading stage.In the filling stage,there was no significant difference between low,medium and high nitrogen treatments.(4)Nitrogen application rate and fertilization method had significant effects on nitrogen use efficiency of double cropping rice.The total nitrogen accumulation of early rice increased with the increase of nitrogen application.The treatment of medium and high nitrogen N2 and N3 was significantly higher than that of low nitrogen N1,and there was no significant difference between N2 and N3.The harvest index of low and medium nitrogen N1 and N2 treatments was higher than that of high nitrogen N3 treatments,and there was no significant difference between N1 and N2 treatments;The physiological utilization rate of nitrogen fertilizer in high nitrogen N3 treatment was 17.6%higher than that in low and medium nitrogen N1 and N2 treatment.The partial fertilizer productivity decreased with the increase of nitrogen application.The low nitrogen N1 treatment was higher than the medium and high nitrogen N2 and N3 treatment,which was 20.20%～43.47%higher.The agronomic utilization rate of medium nitrogen N2 treatment was higher than that of the other two treatments.The total nitrogen accumulation of late rice increased with the increase of nitrogen application.The high nitrogen N3 treatment was higher than other treatments,23.66%～188.38%.The harvest index of low nitrogen N1 treatment was higher than that of medium and high nitrogen N2 and N3 treatment,which were 7.91%and 12.56%higher respectively.The physiological utilization rate of nitrogen fertilizer in medium nitrogen N2treatment was higher than that in low high nitrogen N1 and N3 treatment,which were23.76%and 18.05%higher respectively.The partial fertilizer productivity decreased with the increase of nitrogen application.The low nitrogen N1 treatment was higher than the medium and high nitrogen N2 and N3 treatment,which were 7.17%and 25.27%higher respectively.The agronomic utilization rate of medium nitrogen N2 treatment was higher than that of N1and N3 treatment. |
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