Canopy structure and radiation interception of cotton grown under high density condition in northern Xinjiang
Chunyan Wang*, Akihiro Isoda**, Daolong Wang*, Maosong Li*, Mingyan Ruan*** and Yue Su*
(Institute of Environment and Sustainable Development in Agriculture, China, **Chiba University, ***Shihezi Agricultural and Environmental Institute for Arid Area in Central Asia, Shihezi, Xinjiang, China)

Abstract: 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 1 0 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, uggesting 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, arge 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.
Key words: Xinjiang, Cotton, Growth parameters, Radiation interception, Canopy structure