黄河流域不同密度及施氮量下增效缩节胺化学封顶对棉花生长、产量和熟期的影响

为完善棉花DPC+化学封顶技术的配套栽培措施,于2014和2016年在河北省河间市瀛州镇国欣科技园进行试验。以欣试17为供试品种,在不同栽培密度(6.0万、9.0万和12.0万株/hm2)和施氮(N)量(0、105和210kg/hm2)下研究增效缩节胺25%甲哌鎓(1,1-dimethyl piperidinium chloride,DPC)水剂,以下简称DPC+]化学封顶对棉花生长、产量、地上部干物质积累和分配及熟期的影响。结果表明:与人工打顶相比,DPC+化学封顶的株高增加4.5~7.5cm,果枝数增加2.5~2.6台,叶面积系数(LAI)和地上部干物质积累及其分配无明显变化,铃重增加,铃数略减少,熟期提前,产量无显著变化。随密度增加,棉花株高降低、果枝数减少、中下部果枝缩短、LAI和地上部干物质积累增大。密度对产量和熟期的影响在2个年份不同,2014年(7月份干旱)密度不影响产量和熟期,2016年(7月份多雨)高密度降低产量、延长熟期。施N量不影响棉花生长和产量形成及熟期。此外,棉花LAI、干物质积累和分配、产量及其构成因素和熟期均不受试验因素间(打顶方式、密度和施N量)互作的影响,说明密度和施N量不影响DPC+的化学封顶效果,即化学封顶技术对种植密度和施N量等配套栽培措施的要求可能并不苛刻,这有利于该技术的推广。

Effects of chemical topping with fortified mepiquat chloride on cotton growth,yield and maturity under different plant densities and nitrogen rates in the Yellow River valley region of China

Fortified mepiquat chloride (1,1-dimethyl piperidinium chloride,DPC) is DPC 25% AS (aqueous solution),the component of adjuvant in it could slightly damage the epidermis of young tissues of cotton plants,and thus prolong the period of DPC validity compared with DPC 98% SP (water soluble powder).Therefore,fortified DPC was used for cotton chemical topping to replace manual topping in some regions of China.The objective of this study was to investigate the effects of plant density and nitrogen rate on cotton chemical topping with fortified DPC in Yellow River valley region,and to improve the supporting cultivation measures for cotton chemical topping.Experiments were conducted in Hejian City,Hebei Province in 2014 and 2016 by taking the cotton variety XS17 as material.Compared with the manual topping,the chemical topping with fortified DPC produced 4.5-7.5 cm higher plants and 2.5-2.6 more sympodials,while its leaf area index (LAI),aboveground biomass and allocation between vegetative and reproductive parts had no obvious changes.In addition,the chemical topping increased boll weight,but slightly decreased boll number and did not significantly affect cotton yield.Both open boll percentage in late September and the first harvest seed cotton ratio were enhanced by the chemical topping with fortified DPC.Plant density influenced growth and development of cotton plants,which was characterized by shorter plants,fewer sympdials,shorter lower and middle sympodials,larger LAI as well as increased shoot biomass while plant density increased.The responses of yield and maturity to plant density differed between two years.There were no differences between plant densities in 2014 with a dry July,and the high plant density reduced yield and delayed maturity compared to the low and medium density in 2016 with a wet July.Nitrogen rate did not alter growth and development of cotton plants as well as yield and maturity.Moreover,most traits mentioned above were not significantly influenced by the interactions among topping treatment,plant density and nitrogen rate.It suggests that the cotton chemical topping with fortified DPC possibly did not require specific plant density and nitrogen rate,which was helpful for the generalization of simplified technique in Yellow River valley region.