长江流域棉花短季直播栽培产量形成机制研究

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.

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。

按照项目计划，通过多年多点试验，比较研究了短季直播与传统育苗移栽栽培棉花群体结构、产量构成、光合特性；通过设置不同栽培措施组合试验，构建不同产量水平的短季直播栽培群体，从群体冠层结构形成动态、干物质积累动态和分配特点、光合作用特性、辐射利用特征、产量因素的形成时空分布等方面明确了棉花短季直播栽培产量形成的机理，并对适宜的短季直播栽培的品种特征。短季直播栽培棉花生产周期仅为常规移栽棉60%，其产量形成机理主要表现为：叶面积指数和群体干物质积累启动快、增长迅速，很快达到最大值，很少或没有缓慢增长期；最大LAI较育苗移栽高8%-36%；快速增长期群体日均干物质积累量65 kg/hm2·d1-175kg/hm2·d1，播种后100左右达到最大干物质量；最终株高较育苗移栽矮17%-35%、单株果枝数少30%-45%，果枝与主茎夹角缩小8%-25%；短季直播栽培棉花生长关键时期（盛蕾期和花铃期）群体光截获量大，透光率较育苗移栽群体低20%-70%；全生育期群体光能利用效率显著高于育苗移栽；同一品种SPAD值生长前期与育苗移栽无显著差异，中后期差异极显著；短季直播栽培棉花同品种同一试验点同时期的净光合速率生长前期与育苗移栽无显著差异，至9月下旬，差异达到极显著。短季直播栽培模式下棉花在不同时期的群体光合速率（CAP）和呼吸速率（CR）均随密度增加而提高；短季直播栽培棉铃在植株上的分布较育苗移栽均匀；不同棉花品种对短季直播栽培适应性有差异，单位面积总铃数、子棉产量、皮棉产量的（短季直播/育苗移栽）比值分别在0.71-2.06、0.69-2.05、0.68-2.05之间，短季直播棉花单铃重大多略低于各自的育苗移栽，衣分相对稳定，矮杆品种对短季直播栽培模式的适应性具有显著优势；栽培措施均显著影响短季直播栽培棉花产量的建成，建立了短季直播栽培的高产高效生产模型：y=213.522+3.9331X1+6.414X2-21.4619X3-5.7541X12-4.321X22-7.5348X32-11.982X1X2-0.1645X1X3+3.5747X2X3，其中，X1为施氮量，X2为密度，X3为播期。