新疆石河子棉区高密条件下冠层结构和光分布特征

Canopy Structure and Radiation Interception of Cotton Grown under High Density Condition in Northern Xinjiang

对新疆石河子5个棉花主栽品种全生育期的干物质积累、生长参数、产量和盛铃期的冠层结构、光渗透能力和光分布等进行了测量分析。结果表明,作物生长速率、铃生长率以及子棉产量等均与总受光量呈正相关关系,净同化率则与单位叶面积受光量呈正相关关系,说明受光量是决定干物质生产和产量的重要因素;单位叶面积受光量即光的渗透能力与单位土地面积总受光量呈正相关关系、而与LAI呈负相关关系,说明冠层结构也是影响冠层受光量的主要因素;总受光量与LAI呈显著的正相关关系,说明LAI最大值并未达到最适宜水平。新疆地区棉花高产棉田的主要特征可以总结为叶数少、叶片大、冠层结构为椭圆形。由于叶面积指数尚未达到最适宜水平,增加种植密度可能是提高产量的一个途径。

Five local cotton （Gossypium hirsutum L. ） cultivars, including Xinluzao 6, Xinluzao 8, Xinluzao 10, Xinluzao 11 and Shixuan 87 were grown under high planting density in Shihezi, Xinjiang, China, in 2000. The dry weights of root, stem, leaf, square and boll of ten plants were measured in 2 weeks internals. Leaf area was measured with an automatic area meter. The growth parameters： leaf area index （LAD, crop growth rate （CGR）, net assimilate rate （NAR）, boll growth rate （BGR） were calculated. At boll filling stage, three plants of each replication were chosen for measuring the intercepted radiation with simple integrated solarimeter films. The radiation interception per unit leaf area （IRL） and the amount of radiation interception of each leaf were calculated. LAI and accumulated radiation interception of layer every 10 cm were also calculated. The results showed that IRL had highly significant positive relations to leaf number, and IRG had significant relation to mean leaf area, suggesting that less leaf number but large leaf size would be benefit for radiation interception in cotton cultivars under high planting density. CGR, BGR, total dry matter （TDM） and yield showed significant positive relations to IRG, suggesting that the total radiation interception would be a main factor in dry matter and yield production at boll filling stage. The NAR showed a significant positive relation to IRL, indicating that the ability of radiation interception of leaves at each layer would be important for higher assimilating ability of the canopy. Less leaf number, large single leaf area and the ellipse shape were considered as the characteristics of the ideotype of cotton canopy in radiation interception and dry matter production.