Effects Of Nitrogen Application Rate And Planting Density On Growth,Yield And Nitrogen Use Efficiency Of Rice

The amount of fertilizer and planting density are important factors affecting the growth and yield formation of rice.It is of great significance to determine the suitable planting density and rational application of nitrogen fertilizer for different types of rice to clarify the population formation,yield formation and nitrogen absorption and utilization efficiency under different nitrogen fertilizer rates and machine Transplanting Densities.In this study,hybrid indica rice Liangyoupeijiu,Zhongzheyou 8,japonica hybrid rice Yongyou 1540 and Jiayou 5 were used as materials to carry out mechanical transplanting experiment in field.The split plot design was used in the experiment,and the main plot was nitrogen level.The three nitrogen levels of indica rice were low nitrogen(135 kg/ha),medium nitrogen(153 kg/ha)and conventional nitrogen(180 kg/ha);the three nitrogen levels of Japonica rice were low nitrogen(157.5 kg ha),medium nitrogen(178.5 kg/ha)and conventional nitrogen(210 kg/ha)The results showed that the row spacing of indica rice was 30 cm * 20 cm in low-density treatment,30 cm * 18 cm in medium density treatment,30 cm * 16 cm in high-density treatment,30 cm * 18 cm in low-density treatment,30 cm * 16 cm in medium density treatment and 30 cm * 14 cm in high-density treatment,respectively The growth characteristics,dry matter accumulation,yield formation,lodging resistance and nitrogen absorption and utilization characteristics of different varieties under different nitrogen fertilizer rates and machine planting densities were studied.1.Nitrogen application and mechanical transplanting density significantly affected rice yield and yield components.The yield of Yongyou 1540 was the highest(11.83 × 103 kg /ha)under the treatment of medium nitrogen and high density n178d3,which was higher than that of N178D2(11.21× 103 kg / ha)The yield of Jiayou 5 was the highest under the conventional nitrogen high density N210D3 treatment,but it was not significantly different from that of the conventional nitrogen low density N210D1 treatment(11.17 × 103 kg / ha),but it was significantly higher than other treatments.The yield of hybrid rice Liangyoupeijiu and Zhongzheyou 8 were the highest in the conventional n low density N180D1 treatment,but there was no significant difference between the yield and the medium nitrogen high density N153D3 treatment.The effective panicle number of two japonica hybrid rice varieties increased with the increase of nitrogen application rate and planting density,the highest was in the conventional nitrogen high density N210D3 treatment,the effective panicle number of two indica rice varieties increased with the decrease of planting density under the conventional nitrogen treatment,while the effective panicle number increased with the increase of planting density under the medium and low nitrogen treatment,both in the conventional nitrogen low density N180D1 treatment It’s the highest.The number of grains per panicle of the four varieties decreased with the increase of nitrogen application rate.The planting density of Yongyou 1540 and Jiayou 5 decreased and the number of grains per panicle increased,which was the highest under the treatment of medium nitrogen and low density N157D1.The number of grains per panicle of Liangyoupeijiu and Zhongzheyou 8 increased with the increase of density under conventional nitrogen treatment,and increased significantly with the decrease of density under medium and low nitrogen treatments,which were the highest under low nitrogen and low density N135D1 treatment.The seed setting rate of the four varieties increased with the decrease of mechanical transplanting density,which was the highest in the conventional nitrogen low density treatment.The effects of nitrogen fertilizer and density on 1000 grain weight were not significant.2.The response of stem traits of different varieties to nitrogen fertilizer and mechanical transplanting density was different.When Liangyoupeijiu was treated with medium nitrogen and medium density N153D2,the bending resistance of the first,second and third internodes was the highest,while that of Zhongzheyou 8 was the highest at low density N180D1 of conventional nitrogen,and the bending resistance of Liangyoupeijiu increased with the decrease of planting density under medium nitrogen and conventional nitrogen conditions.Both Yongyou 1540 and Jiayou 5 had the highest bending resistance of the first internode under the treatment of medium nitrogen and medium density N178D2.The bending moment and lodging index of Liangyoupeijiu and Zhongzheyou 8increased with the increase of nitrogen application rate,and the lodging index increased with the increase of nitrogen application rate,and reached the maximum value at the conventional nitrogen medium density N180D2.There was no significant difference in bending moment and lodging index in different treatments of Yongyou 1540.The bending moment and lodging index of Jiayou 5 were in the N210D1 of conventional nitrogen low density It is the largest under the piece.3.Accumulation and nitrogen use efficiency of rice.The nitrogen content of different varieties increased with the increase of nitrogen application rate,but there was no significant difference among different planting densities under the same nitrogen application rate.At maturity stage,the nitrogen content of stem sheath and leaf of Yongyou 1540 was highest in conventional nitrogen low density N210D1,and Panicle Nitrogen content was the highest in conventional nitrogen medium density N210D2.The nitrogen accumulation of rice could be improved by increasing nitrogen fertilizer and planting density.The total nitrogen accumulation of Yongyou 1540 and Jiayou 5 reached the maximum at the conventional nitrogen high density N210D3,and the total nitrogen accumulation increased with the increase of machine planting density.Nitrogen use efficiency(NUE)decreased with the increase of nitrogen application rate,and the planting density significantly affected nitrogen use efficiency.The results showed that the agronomic efficiency(NAE)of Yongyou 1540 and Jiayou 5 reached the maximum at N157D3 with low nitrogen and high density,increased by 16.2%-68.2% compared with other treatments;the agronomic efficiency NAE of Liangyoupeijiu reached the maximum value at N135D1 of low nitrogen and low density,increased by 10.5%-47.4% compared with other treatments,and the NAE of Zhongzheyou 8 reached the maximum at N135D1 with low nitrogen and low density,increased by 4.1%-42.8% compared with other treatments,There was no significant difference between the two treatments.In conclusion,rice yield could be higher under conventional nitrogen application rate and appropriate mechanical transplanting density,but the yield of four varieties under medium nitrogen(15% less than conventional nitrogen treatment)high density treatment was equivalent to or slightly lower than that of conventional nitrogen treatment,and it was helpful to increase dry matter accumulation,lodging resistance and nitrogen use efficiency of rice,indicating that nitrogen fertilizer(basal and tiller fertilizer)should be appropriately reduced However,the increase of mechanical transplanting density will not significantly reduce rice yield,but also help to enhance rice lodging resistance and nitrogen use efficiency.