| To investigate the effects of different rates and methods of side-dressing fertilization on nitrogen utilization,nitrogen transportation,ammonia volatilization,dry matter accumulation of plants,and the yield of rice,this study aimed to explore appropriate nitrogen reduction strategies for side-dressing fertilization while ensuring rice yield.The rice variety"Quanliangyou E’Fengsimiao"was used as the material for this study from2020 to 2022.The following treatments were set up:no fertilizer application throughout the growth period(H0),one-time application of controlled-release fertilizer with deep placement(H1),one-time application of controlled-release fertilizer with a 10%reduction and deep placement(H2),one-time application of controlled-release fertilizer with a 20%reduction and deep placement(H3),and traditional broadcasting application(CK).The study aimed to investigate the effects of one-time application of controlled-release fertilizer with deep placement on rice growth,nitrogen utilization,and yield.The results are as follows:(1)In terms of rice growth,compared to the traditional broadcasting application(CK)as the control,the various treatments of controlled-release fertilizer showed slower tillering during the early tillering stage after regreening and a delayed tillering peak during the seedling stage.However,they exhibited higher effective panicle numbers and panicle formation rates.Among the treatments,H1 and H2 had effective panicle numbers 7.94%to 12.99%and 2.74%to 6.73%higher than the control,respectively,while H1,H2,and H3 had effective panicle formation rates 9.52%to 11.97%higher than the control.The leaf area index,SPAD values,and dry matter accumulation of the controlled-release fertilizer treatments were relatively lower during the early growth stage but higher than the control during the later stage of development.The average root length,average root surface area,and average root volume in the fertilized area of the controlled-release fertilizer treatments were significantly higher than the control.There were no significant differences among the various controlled-release fertilizer treatments,but compared to the unfertilized area,the average root length was 9.01%to 16.90%higher,the average root surface area was 9.29%to 15.35%higher,and the average root volume was 18.59%to 40.51%higher.In the no-fertilizer treatment(H0),the root system was distributed relatively shallow in the soil,mainly concentrated within the 0-10 cm range vertically and within the 0-15 cm range along the plant axis horizontally.The root system of the CK treatment was mainly distributed within the 0-15 cm range vertically and within the 0-20cm range along the plant axis horizontally.The distribution patterns of the root systems in the H1,H2,and H3 treatments were similar.They were mainly distributed within the5-15 cm range vertically,with the fertilized area having a higher distribution between 15-25 cm compared to the unfertilized area.In the horizontal distribution,the fertilized area exhibited a greater breadth than the unfertilized area.Some of the root systems in the fertilized area were distributed within the 15-25 cm range from the plant axis,while the root systems in the unfertilized area were mainly distributed within the 0-15 cm range from the plant axis.(2)Regarding ammonia volatilization,compared to the control,the various treatments of controlled-release fertilizer exhibited significantly lower volatilization rates during the different stages of the growth period.The total amount of ammonia volatilization in the CK treatment was 2.60 times,2.71 times,and 3.02 times higher than in the H1,H2,and H3 treatments,respectively.The soil ammonium nitrogen content in the controlled-release fertilizer treatments reached its peak later compared to the CK treatment.The nitrogen fertilizer applied in the CK treatment remained in the soil for a shorter duration.The peak value of soil ammonium nitrogen content in the CK treatment was 14.36%to 22.47%lower than in the H1,H2,and H3 treatments.(3)In terms of nitrogen utilization,compared to the control,the various treatments of controlled-release fertilizer showed slower nitrogen accumulation rates in the leaves and stems of the plants before the tillering stage.As the growth period progressed,the nitrogen accumulation rates in different parts of the plants in the controlled-release fertilizer treatments were higher than in the control.Ultimately,the nitrogen accumulation in the H1 treatment was significantly higher than in the CK treatment.In terms of nitrogen utilization efficiency,the nitrogen apparent utilization efficiency,agronomic efficiency of nitrogen,physiological efficiency of nitrogen,and partial factor productivity of nitrogen in the controlled-release fertilizer treatments were higher than in the CK treatment.Compared to the various treatments of controlled-release fertilizer,the nitrogen apparent utilization efficiency in the CK treatment was lower by 1.21%to 46.57%,the agronomic efficiency of nitrogen was lower by 18.85%to 68.37%,the physiological efficiency of nitrogen was lower by 10.62%to 28.43%,and the partial factor productivity of nitrogen was lower by 13.93%to 24.74%.(4)Regression analysis reveals that there is a quadratic relationship between the nitrogen reduction in one-time application of controlled-release fertilizer with deep placement and rice yield,with an upward-opening parabolic curve.Solving the regression equation y=0.0004x~2-0.0727x+9.9467 shows that when the total nitrogen reduction in controlled-release fertilizer reaches 19.55%,the rice yield is equal to that of the CK treatment.Compared to the CK treatment,the H1 and H2 treatments significantly increase yield by 12.99%to 14.96%and 5.47%to 6.17%,respectively.There is no significant difference in yield between the H3 treatment and the CK treatment.In summary,replacing traditional broadcasting with one-time application of controlled-release fertilizer with deep placement can improve the tillering potential of rice in the mid to late stages,promote root growth,increase root biomass,enhance the number of effective panicles per unit area,and improve panicle formation rate.It also leads to higher leaf area index and dry matter accumulation in the mid to late stages of development,increased SPAD values,and reduced leaf senescence rate in the later stages of rice growth.Additionally,it improves the nitrogen apparent utilization efficiency,agronomic efficiency of nitrogen,physiological efficiency of nitrogen,and partial factor productivity of nitrogen,thus increasing rice yield.Compared to reducing nitrogen application by less than 10%through traditional broadcasting,significant yield increases can be achieved in machine-transplanted rice.Regression analysis indicates that one-time application of controlled-release fertilizer with deep placement can maintain stable yields and increase efficiency when nitrogen reduction is within 19.55%. |
PDF Full Text Request