施氮量和密度互作对全覆膜旱作甜菜光合特性和块根产量的影响

全覆膜具有增温、保墒和压草的作用,是干旱区农作物种植的有效措施。为探索旱作甜菜在全覆膜条件下的适宜施氮量和种植密度,采用二因素裂区试验设计,研究施氮量和密度不同组合处理对全覆膜旱作甜菜光合特性的影响,为旱作甜菜高产栽培提供依据和参考。研究结果表明,全覆膜条件下施氮水平和密度对旱作甜菜光合特性影响的互作效应显著;适宜的施氮量和密度配置有利于甜菜SPAD值、叶面积指数、净光合速率（P_n）、单株干物质积累量、根冠比以及块根产量的提高,SPAD值、叶面积指数、P_n、单株干物质积累量均与产量呈正相关。在甜菜块根糖分增长期,SPAD值和叶面积指数分别维持在53.8和4.5时,旱作甜菜产量最大;通过二项式回归分析建立密度和施氮量与产量的回归方程,得出全覆膜旱作甜菜高产适宜的种植密度为9.35万株/hm ²,施氮量为128.8kg/hm ²。

Effects of Nitrogen Application Rate and Planting Density Interaction on Photosynthetic Characteristics and Root Yield of Sugar Beet under Full-Film Mulching in Arid Regions

Full-film mulching has the advantages of increasing temperature, preserving moisture and suppressing grass, and it is an effective measure for dryland farming. Herein, a two-factor split-plot design was used to explore suitable nitrogen application and planting densities of sugar beet under full-film conditions in arid regions. Comparative study on photosynthetic characteristics and yields under full-film mulching condition through different combinations of nitrogen application rates and planting densities showed that nitrogen supply and planting density had significant effects on photosynthetic characteristics of sugar beet under full-film conditions under dry conditions. The suitable nitrogen and density were beneficial to SPAD value, LAI (leaf area index), net photosynthetic rate (P_n), the accumulation of dry matter per plant, T/R, and yields of beet. In addition, SPAD value, LAI, P_n, T/R, and dry matter accumulation per plant were positively correlated with yields. During the increasing stage of sugar beet root, the maximum yields could be obtained when the SPAD value and LAI of sugar beet were controlled at 53.8 and 4.5, respectively. The regression equation of density (X₁) and nitrogen application (X₂) with yields (Y) was obtained by binomial regression analysis. The maximum yields of sugar beets could be obtained when the density was 93 500 plant/hm ² and the nitrogen application rate was 128.8kg/hm ².