Effect of Reducing Nitrogen and Increasing Density on Yield and Nitrogen Absorption and Utilization of Rice in Cold Region
The long-term experiment with reduced nitrogen and increased density for rice in cold region under straw return was started in 2017.A total of the following five treatments were set up,CK:conventional density(30 cm×13.3 cm),no N fertilizer;T1:conventional density(30 cm×13.3 cm),conventional N application rate(180 kg/ha);T2:increasing density by 32％(30 cm×10 cm),conventional N application rate(180 kg/ha);T3:increasing density by 32％(30 cm×10 cm),20％reduction in total conventional N application rate by spike fertilizer(total N application rate of 144 kg/ha);T4:increasing density by 32％(30 cm×10 cm),20％reduction in total conventional N application rate by basal fertilizer(total N application rate of 144 kg/ha).The experiment data in 2023 was used to study the effect of reducing nitrogen and increasing density on yield and nitrogen absorption and utilization of rice.The results showed that T4 treatment had the highest yield,which was significantly increased by 39.6％,9.8％and 13.3％compared with CK,T1 and T2 treatments respectively;T3 treatment was the second,showing no significant difference from T4 treatment.The increase of yield of the two treatments was mainly attributed to the increase of effective spikes number,and T4 treatment significantly increased by 64.0％and 18.5％compared with CK and T1 treatment respectively.The harvest indexes of T3 and T4 treatments were higher,and the difference between them was not significant,but both were significantly higher than the other treatments,among which T4 treatment was 30.4％,53.3％and 15.6％higher than CK,T1 and T2 treatments respectively.From jointing stage to mature stage,T4 treatment generally had the highest SPAD value of leaves,the lowest attenuation rate of SPAD,and higher dry weight of above-ground part.T1—T4 treatments significantly increased nitrogen uptake by 53.6％—94.2％compared with CK,and the increase was the greatest in T4 treatment.Compared with the T1 treatment,the nitrogen fertilizer uptake and use efficiency,nitrogen uptake rate,nitrogen fertilizer agronomic utilization rate and nitrogen partial productivity of T4 treatment significantly increased by 36.1％,30.1％,82.4％and 37.3％,respectively,whereas apparent surplus and deficit of soil nitrogen and nitrogen surplus rate significantly decreased by 87.5％and 103.8％,respectively;the nitrogen fertilizer uptake and use efficiency of T3 treatment significantly decreased by 22.5％,while nitrogen fertilizer agronomic utilization efficiency and nitrogen partial productivity significantly increased by 71.2％and 34.9％.Nitrogen partial productivity,nitrogen fertilizer agronomic utilization rate,nitrogen uptake rate were significantly positively correlated with yied,and nitrogen surplus rate and soil nitrogen apparent surplus and deficit were significantly negatively correlated with yield.In conclusion,increasing density while reducing the amount of basal nitrogen fertilizer can improve rice yield as well as nitrogen uptake and utilization rate,which is more suitable for the growth of rice in cold region.
RiceCold regionReducing nitrogen and increasing densityYieldNitrogen absorption and utilization
万方数据
维普
