长江流域传统棉花栽培全生育期200天以上且吐絮历期长，已成为全程机械化的瓶颈和生产效益低的主要原因。利用棉花无限生长习性及生育期和株型可调控性，综合运用栽培措施发挥群体生产能力，5月下旬直播，10月15日前吐絮结束，全生育期缩短至140天左右(专利号：ZL2013 1 0453340.5)，为长江流域棉田耕作制度根本变革和机械化创造了条件。但针对这种短季直播栽培的生理基础研究还很薄弱，如何在传统栽培2/3的时间内获得相当的产量？其产量形成的机制尚不清楚。本项目拟以不同产量水平的短季直播群体和传统栽培群体为对象，系统研究不同群体冠层结构和光分布特征、个体和群体水平的光合与物质分配特性、不同生育阶段的RUE等，从群体结构和光能利用的角度，探明棉花短季直播栽培产量形成的机制，确立其高产群体结构及各生育阶段光能利用的定量化指标，为长江流域棉花短季直播高产栽培提供理论基础。

It has become a bottleneck of the completely mechanical production and the main reason of low productivity efficiency of cotton, because of the long whole growth period (the durations from sowing to end of production) and long duration of maturity(the persistent period of first boll open to almost all bolls open) of traditionally cotton culture in the Yangtze River Valley. As cotton is an indeterminate species, the growth period and plant type can be regulated. Through comprehensive cultivation measures to develop the population production capacity, the full growth period has been shortened from over 200 days to approximately 140 days that direct seeding in the late May and full maturity (95% bolls opening) before October 15th, and this culture has obtained the China National Invention Patent (ZL2013 1 0453340.5). However, the research of physiological basis is still very weak about this new short-season direct-seeding cultural method. How to obtain quite production in about two-thirds time of traditional cultivation? It is still unclear that the characteristic parameter and development trend of canopy structure, photosynthetic production and distribution, temporal-spatial distribution of yield factors, radiation use efficiency (RUE) of high-yield population, etc., in the short-season direct-seeding cultural system. In order to provide theoretical basis for short-season variety breeding and high-yield cultivation of cotton in the Yangtze River Valley, this project will systematic research the mechanism of short-season direct-seeding cotton yield formation, from the perspective of population structure and radiation utilization. Through verifying the canopy structure and light distribution in the population, photosynthetic properties of individual and population level, RUE in different growth period, etc, based on short-season direct-seeding population of different yield level, traditional cultivating population, and the quantitative indicators of the high-yielding population canopy structure and the radiation utilization in each growth period will be established.