Effects of Different Nitrogen Application Rates and Planting Densities on Population Growth and Yield Components of Rice

【Objective】 To study the effects of different nitrogen application rates and planting densities on the population growth and yield characteristics of rice in southern Xinjiang, so as to provide basis for rational close planting and optimal nitrogen management in production. 【Methods】 Xindao 36 was selected to carry out a split plot field experiment with four nitrogen application rates (pure nitrogen 0, 120, 240 and 360 kg/hm², represented by N₀, N₁, N₂ and N₃) in the main area and five planting densities (13.89, 16.67, 20.83, 27.78 and 41.67×10⁴ holes/hm², represented by D₁, D₂, D₃, D₄ and D₅) in the sub area. The stem and tiller dynamics, dry matter accumulation, yield composition and rice quality characteristics were analyzed. 【Results】 (1) Appropriately increasing planting density and nitrogen application rate was conducive to increasing the number of tillers in rice population, the number of final tillers of N₂D₄ was the largest, reaching 4.13×10⁶ stems/hm²;(2) The rapid growth period of dry matter of rice population in southern Xinjiang was from jointing to the middle and late filling stage, and tended to prolong with the increase of nitrogen application. The final dry matter accumulation was manifested as N₃>N₂>N₁>N₀. Too high density was unfavorable to dry matter accumulation, and the final dry matter accumulation was D₄>D₅>D₃>D₂>D₁; (3) The number of grains per panicle of N₂ and D₁ was the largest, and the excessive nitrogen application was unfavorable to the improvement of seed setting rate, grain weight and tillering panicle rate. With the increase of nitrogen application rate and planting densities, the number of effective panicles and yield increased first and then decreased. The number of effective panicles and yield of N₂D₄ were the largest, reaching 3.99×10⁶ panicles/hm² and 13.61 t/hm² respectively, followed by N₃D₄, 3.71×10⁶ panicles/hm² and 12.94 t/hm²; (4) Density had little effect on rice quality, and increasing nitrogen fertilizer was beneficial to increase protein content, brown rice rate and milled rice rate, and to improve quality. 【Conclusion】 The nitrogen application rate is 240-360 kg/hm² and the planting density is 27.7878×10⁴ holes /hm² (30 cm × 12 cm) for higher yields.