黄淮海夏玉米品种脱水类型与机械粒收时间的确立

黄淮海一年两熟模式下玉米成熟和熟后籽粒脱水的热量资源紧缺,是制约机械粒收在该区域发展的关键因素。本文尝试建立黄淮海一年两熟制地区玉米机械粒收适宜品种筛选和以授粉至生理成熟积温和生理成熟期籽粒含水率为指标,运用双向平均法将参试品种划分为晚熟高含水率(I)、早熟高含水率(II)、早熟低含水率(III)和晚熟低含水率(IV)4种类型。基于玉米生长进程及籽粒含水率动态测试,估算不同品种播种至适宜机械粒收含水率(28%、25%)所需活动积温,以黄淮海区夏玉米常年播种日期为起点,结合历史气象资料的累积计算,利用地统计分析技术明确不同类型品种适宜机械粒收的时空分布规律,建立适宜机械粒收时期的预测方法,为机械粒收在黄淮海区域推广提供指导。选择27个主推品种,播种至籽粒含水率下降到28%、25%所需要积温分别为,类型I 2982°C d、3118°C d,类型II 2770°C d、2873°C d,类型III 2729°C d、2845°C d,类型IV 2860°C d、2980°C d。类型III品种降至28%、25%含水率时间分别较类型II品种早2～3 d、约2 d,较类型IV品种早7～9 d、7～10 d,较类型I品种早13～17 d、16～17 d。各类型品种籽粒由28%含水率降至25%水平,所需时间约6～8d。在当前玉米种植模式及下茬小麦适期播种条件下,黄淮海南部的豫南、皖北地区,各类玉米品种均能满足籽粒脱水至适宜机械粒收含水率的要求,而在黄淮海北部、关中西部以及山东半岛地区,现有品种很难降至适宜含水率,需通过选择早熟和籽粒脱水快的适宜品种加以实现。本研究建立的以积温预测籽粒含水率动态变化及其适宜机械粒收时间的预测方法,为各地合理配置玉米粒收品种、确定适宜机械粒收时间提供了可行的技术方法。

Grain Dehydration Types and Establishment of Mechanical Grain Harvesting Time for Summer Maize in the Yellow-Huai-Hai Rivers Plain

The wheat-maize double cropping system limits the heat resources of maize ripening and dewatering, which is the key factor to restrict the development of mechanical grain harvesting in the Yellow-Huai-Hai Rivers Plain. In this paper, methods of the optimum cultivar selection and harvesting time forecast were established to provide guidance for the promotion of mechanical grain harvesting in the double cropping system of the Yellow-Huai-Hai Rivers Plain. Twenty-seven main planting cultivars were selected and divided into four types by using the two-way average method. This method based on two parameters including the accumulated temperature from pollination to physiological maturity and the grain moisture content at physiological maturity. These four types were the later maturing and higher moisture content (I), the earlier maturing and higher moisture content (II), the earlier maturing and lower moisture content (III) and the later maturing and lower moisture content (IV). When grain moisture content reduced to 28% and 25% (suitable for mechanical grain harvesting) the cultivars’ active accumulated temperatures were simulated based on measurements of vegetative growth stage and dynamic change of grain moisture. According to the accumulated temperature and the historical meteorological data, the suitable days for mechanical grain harvesting of different cultivar types were estimated by using the geostatistical analysis method based on the starting points of normal sowing dates in the Yellow-Huai-Hai Rivers Plain, thus establishing the prediction method of optimum dates for mechanical grain harvesting. The accumulated temperatures from sowing to the time reaching grain moisture of 28% and 25% were 2982°C d and 3118°C d (I), 2770°C d and 2873°C d (II), 2729°C d and 2845°C d (III), and 2860°C d and 2980°C d (IV), respectively. The time for the type III cultivar with 28% and 25% moisture content respectively was two to three days and about two days earlier than that for the type II cultivar, seven to nine days and seven to ten days earlier than that for the IV type cultivar, and thirteen to seventeen days and sixteen to seventeen days earlier than that for the type I cultivar. All types of cultivar needed six to eight days to reduce grain moisture from 28% to 25%. Under the current maize cropping pattern and the sowing date of following wheat, all maize cultivars could be planted for mechanical grain harvesting in southern Henan and northern Anhui provinces in the southern Yellow-Huai-Hai Rivers Plain, while no cultivars could be used in the northern Yellow-Huai-Hai Rivers Plain, Guanzhong Area, and Shandong Peninsula where the mechanical grain harvesting of summer maize should be realized by selecting cultivar with the shorter maturing date and the rapid dehydration characteristic. In this study, the method to predict the dynamic change of grain moisture content and the optimum time of mechanical grain harvesting was established by the accumulated temperature. This method provides a feasible technical means for rationally distributing the grain harvesting cultivars and determining the suitable harvesting time.