Effects Of Nitrogen Fertilizer And Sowing Density On Yield And Lodging Resistance Of Double-seeded Direct Seeding Rice

In recent years,a large number of young and middle-aged labors in rural areas have been transferred to cities,and rural labors are in short supply.The traditional techniques for transplanting rice seedlings are time-consuming and laborious,resulting in severe challenges for rice production in China.Therefore,it is urgent to explore a light and simplified cultivation model.Direct seeding is a cultivation technique that directly germinates the germinated seeds in a humid field.It has the characteristics of saving labor and effort.It can be seen that the development of double-season direct seeding technology is an effective way to solve this problem.Nitrogen fertilizer and seeding density are two important factors that affect direct seeding production,both of which can affect the population structure and plant characteristics of direct seeding rice,as well as the yield and lodging resistance of direct seeding rice.However,there is no final conclusion about the best collocation pattern of seeding density and nitrogen fertilizer.This experiment uses field experiments,using Zhongjiazao 17 and Taiyou 871 as research materials,In early rice in2018,two planting densities(L₃₀:30 kg/hm²and H₆₀:60 kg/hm²,)were set,and the nitrogen fertilizer application rate was(N₁₂₀:120 kg/hm²,N₁₆₅:165 kg/hm²,N₂₁₀:210kg/hm²);In the late rice in 2018,three planting densities were set:(L₃₀:30 kg/hm²,M₄₅:45kg/hm²,H₆₀:60 kg/hm²),and the nitrogen fertilizer application rate was(N₉₀:90kg/hm²,N₁₈₀:180 kg/hm²,N₂₇₀:270 kg/hm²);Three seeding densities were set,respectively(L₂₀:20 kg/hm,M₄₀:40 kg/hm²,H₆₀:60 kg/hm²)and The nitrogen fertilizer application rate is set as(N₈₀:80 kg/hm²,N₁₆₀:160 kg/hm²,N₂₄₀:240 kg/hm²)in 2019,and conducts experimental research on the relationship between two years of different nitrogen fertilizer and seeding density treatment and the emergence rate,plant lodging resistance and yield.The results show that nitrogen fertilizer has a significant effect on the yield of early and late rice,density has a significant effect on the yield of two-year early rice,and the effect on the yield of two-year late rice has not reached a significant level,and there is a significant interaction between nitrogen fertilizer and density on the yield of two-early rice effect.Under the conditions of low and medium density,the yield increases with the increase of nitrogen fertilizer,and vice versa at high density.Under the same nitrogen application rate,the yield increased with the increase of density.The yield of direct-seeded rice in 2018 and 2019 was the highest under the treatments of H₆₀N₁₂₀,H₆₀N₉₀ and H₆₀N₈₀.Compared with the treatments of H₆₀N₁₂₀,H₆₀N₉₀ and H₆₀N₈₀,the other treatments were in the early and late 2018 The reduction rates in the early and late seasons of 2019 are 3.14%to 18.14%,1.22%to 13.17%,6.64%to 26.84%,1.99%to 16.02%;Under the condition of low nitrogen and high density,the seeding rate of direct seeding rice is high,and the accumulation of above-ground biomass in the tillering period to the ear panicle differentiation period is much.The energy radiation interception rate is the highest,the total biomass in the mature period is large,the harvest index is high,the effective ear number and the number of grains per ear are more.At the same density,with the increase of nitrogen application,the lodging index increased.Under the same nitrogen application rate,the lodging index of N₁₂₀,N₉₀ and N₈₀treatments showed M>L>H,and the lodging index of other nitrogen fertilizer levels showed an increase with the increase of density.The intersegment length and the proportion of intersegment height of plant stems are the smallest.The intersegment dry weight,unit intersegment length dry weight,base second intersegment stem thickness,wall thickness,and flexural strength are all the largest.The influence of mechanical and morphological characteristics between the second section.When the seeding density was60 kg/hm² and the nitrogen application rate was 80-120 kg/hm²,the lodging index was the smallest.In sum,under the conditions of this experiment,when the seeding density is 60kg/hm² and the nitrogen application rate is 80-120 kg/hm²,the direct-seeded rice is high-yield and resistant.