摘要:机械粒收技术是现代玉米生产的关键技术，籽粒机收率低已成为黄淮海夏玉米全程机械化生产的主要限制因素。籽粒含水量是决定能否机械粒收的关键指标，但直接测定籽粒含水量工作量繁重，取样误差因素多，破坏性大。利用生理成熟后籽粒脱水速率与光温条件的拟合关系，通过建立不同品种达到机收标准所需光温指标来反推籽粒含水量，间接实现对籽粒含水量的动态监测，指导适时机收，可克服上述缺点，为促进夏玉米机械粒收技术发展，指导农业生产发挥重要作用。本研究选择24个鹤壁主要种植玉米品种为供试材料，采取统一授粉，每隔3 d连续测定籽粒含水量变化。利用播种至收获期积温和乳熟至收获期日照时数与不同时期籽粒含水量进行回归分析，建立各品种拟合方程，以籽粒含水量达到28%为适宜机收的阈值，推算相应的光温指标。研究结果表明，除‘新单38’外，籽粒含水量均表现为果穗上部 < 果穗中部 < 果穗下部，‘先玉335’、‘登海701’、‘德单5号’和‘新单61’果穗上中下各部分的籽粒含水量差别较大。各品种达到适宜机收标准时所需播种到收获期积温在2 941~3 147℃·d范围内变化，所需乳熟至收获期日照时数为179~235 h。将各品种光温指标分别排序，光照和积温确定的品种位次较一致。经检验各品种达到机收标准的光温指标与收获期籽粒含水量呈极显著正相关，表明研究建立的光温指标能准确反映各品种籽粒含水量的变化，可用来指导机收。根据各品种光温指标大小，‘新单65’、‘新单68’、‘登海618’、‘新单38’、‘隆平206’、‘登海3号’、‘先玉335’和‘新单80’等品种达到机收标准所需的光温条件较少，更适宜籽粒机收；‘豫禾988’、‘郑单958’、‘登海662’、‘登海518’、‘新单66’、‘登海605’、‘德单5号’和‘益丰29’，成熟后脱水较慢，相对而言较不适宜籽粒机收。
关键词:黄淮海/
夏玉米/
籽粒机收/
籽粒含水量/
光温指标
Abstract:Mechanical grain harvest is a key technology in modern maize production. Low percent of mechanical harvest is the factor limiting fully mechanized production of summer maize in the Huang-Huai-Hai Plain. Grain moisture content is the key index of mechanical grain harvest, but measurement of grain moisture content is tedious and complicated, prone to error and destruction while sampling. Grain moisture content is closely related to weather conditions. Based on the relationship among dehydration rate after physiological maturity, sunshine duration and accumulated temperature, grain moisture can indirectly be calculated. Thus building sunshine and temperature indexes for the suitability of mechanical grain reaping of different varieties can overcome the above shortcomings. It also can guide timely mechanical harvest and promote the development of mechanical grain harvest technology. In 2015 and 2016, 24 main cultivated cultivars in the Agro-meteorological Experiment Station of Chinese Meteorological Administration in Hebi City, Henan Province were investigated. Controlled pollination was used in every cultivar. Grain weight and moisture content were measured every third day after milk line reached half kernels of middle ear grains. The accumulated temperature from sowing to sampling and sunshine duration from milking stage to sampling were set as the independent variables, and grain water content in different times as dependent variables for regression analysis. And the regression equations were validated by test of significance. The sunshine and temperature indexes suitable for mechanical grain harvest of different varieties were calculated based on the threshold value of 28% grain moisture content by fitting the equations. The results showed that the order of grain moisture content in the same ear was upper part < middle part < lower part for all the tested varieties, except 'Xindan 38'. The grain moisture content in different parts of ear differed greatly in 'Xianyu 335', 'Denghai 701', 'Dedan 5' and 'Xindan 61'. The suitable accumulated temperature from sowing to harvest was 2 941-3 147℃·d and the suitable sunshine duration during milking stage to harvest stage was 179-235 h for mechanical grain harvesting of different varieties of summer maize. Sunshine duration and accumulated temperature were sorted from small to big, which showed a good consistency of variety order between temperature index and sunshine index. T-test showed that sunshine duration and accumulated temperature were significantly positively correlated with grain moisture content at harvest (P < 0.01). This indicated that sunshine and temperature indexes established in the study accurately reflected the changes in grain moisture content in each variety, and could be used to guide mechanical grain harvest. Base on sunshine and temperature indexes, 'Xindan 65', 'Xindan 68', 'Denghai 618', 'Xindan 38', 'Longping 206', 'Denghai 3', 'Xianyu 335' and 'Xindan 80' varieties needed less accumulated temperature and sunshine duration to meet mechanization standards and therefore more appropriate for mechanical grain harvest. However, 'Yuhe 998', 'Zhengdan 958', 'Denghai 662', 'Denghai 518', 'Xindan 66', 'Denghai 605', 'Dedan 5' and 'Yifeng 29' varieties had slower dehydration rates after maturity and therefore relatively less suitable for mechanical grain harvest.
Key words:Huang-Huai-Hai Plain/
Summer maize/
Mechanical grain harvest/
Grain moisture content/
Sunshine and temperature indexes
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