摘要：

播期调整是直接有效减缓气候变化对农业负面影响的重要措施,为了揭示播期变化对作物产量形成的影响机制,在华北北部的河北固城农业气象国家野外科学观测研究站,于2019—2021年设置早播10 d、晚播10 d、晚播20 d和正常播期4个播期,进行了夏玉米同一品种播期调整的大田试验,监测其生育期变化、植株干物质累积、叶片光合特性和籽粒灌浆特征,以及成熟期取样测定产量构成等要素。结果表明:夏玉米播期提前,苗期、穗期及全生育期延长,尤其有效灌浆持续日数随播期提前而延长,播期每提前10 d有效灌浆持续日数延长4.7 d,播期提前10 d平均灌浆速率比对照和晚播10,20 d的平均偏高4.04%,籽粒灌浆、累积增加,百粒质量提高5.459 g。夏玉米穗粒数、穗粒质量、百粒质量等主要产量构成要素在不同播期间存在显著差异,且随播期提前而递增,在6月8日—7月8日试验期理论产量随播期每提前10 d增产速率为1 395.4 kg/hm²。夏玉米关键生育期平均叶片净光合速率(Pn)随播期每提前10 d提高0.764 μmol/(m²·s),播期提前10 d比对照和晚播10,20 d的平均Pn提高7.31%。光合速率提高使得干物质生产、积累及向籽粒转运量增加,穗粒质量、百粒质量分别比对照和晚播10,20 d的平均偏高24.01%,18.00%。播期提前,株高低,茎秆粗壮,抗倒伏,个体绿叶面积大,群体叶面积指数(LAI)高,叶片光合作用能力高,播期每提前10 d成熟期地上干物质分配率:籽粒质量递增率2.26%,植株营养器官—果穗籽粒间干物质的源—库分配关系改变,穗粒质量、百粒质量提高和籽粒增产。研究认为:华北地区冬小麦—夏玉米一年两熟区充分利用气候变暖增加的热量资源,合理调配茬口,夏玉米适期早播,延长生育期和籽粒灌浆时间,可有效提高单产。

关键词: 夏玉米, 华北北部, 播种期, 生长特征, 增产效果

Abstract:

In order to reveal the influence mechanism of sowing date adjustment on crop yield formation, a field experiment was conducted to adjust the sowing date of the same variety of summer maize from 2019 to 2021 at Hebei Gucheng Agricultural Meteorology National Observation and Research Station in Northern north China, which was set up in four sowing date, as 10 d early sowing, 10 d late sowing, 20 d late sowing and control. By monitoring the growth period changes, plant dry matter accumulation, leaf photosynthetic characteristics and grain filling characteristics, and sampling at maturity to determine the yield components, the results showed that:the sowing date of summer maize was appropriate to be advanced,the seedling stage,ear stage and the whole growth period were extended,especially,the duration of effective filling was extended with the advance of sowing date.The effective grain filling duration days were extended by 4.7 days for every 10 days ahead of the sowing date.The average filling rate of winter wheat was 4.04% higher on the sowing date was advanced by 10 days, compared with the sowing date was deferred by 10 or 20 days and the control.Grain filling accumulation increased,and 100-grain weight increased by 5.459 g.The main yield components of summer maize,such as grain number per ear,grain weight per ear and 100-grain weight showed significant differences during sowing,and increased with the sowing date.The theoretical yield increased by 1 395.4 kg/ha with 10 days ahead of the sowing date during the experimental period from June 8 to July 8.The average net photosynthetic rate(Pn)of leaves in the critical development period of summer maize increased by 0.764 μmol/(m²·s)with every 10 days ahead of sowing date,and the average Pn of sowing date 10 days earlier was increased by 7.31% compared with the control and late sowing 10 and 20 days.With the increase of photosynthetic rate,dry matter production,accumulation and transfer to grain were increased,and the grain weight per ear and 100-grain weight increased by an average of 24.01% and 18.00%,respectively,compared to the control and late sowing 10 and 20 days.Advancing sowing date resulted in low plant height,strong stems,lodging resistance,large individual green leaf area,high leaf area index(LAI),and high leaf photosynthesis ability,above-ground dry matter allocation rate at maturity stage every 10 days in advance of sowing date:grain weight improved by 2.26%,the source—pool distribution of dry matter between plant vegetative organ and ear changed,ear weight per ear,100-grain weight and grain yield increased.The research showed that the double cropping area of winter wheat—summer maize in north China could effectively improve the yield per unit area by making full use of the heat resources increased by climate warming,reasonably allocating stubble,sowing summer maize early at the appropriate time,and extending the development period and grain filling time.

Key words: Summer maize, Northern north China, Sowing date, Growth characteristics, Yield-increasing effect