宁夏玉米机械粒收适宜时期研究与预测模型构建

Study on Optimal Time and Construct a Prediction Model of Mechanical Grain Harvest of Maize in Ningxia

【目的】在宁夏地区不同播期条件下,对不同脱水类型玉米品种籽粒含水率降至适宜机械粒收含水率的日期进行预测,为区域品种选择、适宜收获期的确定及低水分粒收技术提供支撑。【方法】本研究以38个主栽玉米品种为材料,以生理成熟期平均含水率(30.1%)和播种至生理成熟≥0℃的平均积温(3274℃·d)为指标,采用双向平均法将38个品种分为晚熟脱水慢(Ⅰ类)、早熟脱水慢(Ⅱ类)、早熟脱水快(Ⅲ类)和晚熟脱水快(Ⅳ类)4种类型,结合宁夏生产实际,在每类型品种中选择出生理成熟期籽粒含水率和积温需求居中的品种作为各类型的代表品种;采用Logistic Power非线性增长模型构建玉米品种脱水方程,结合近10年(2008—2017年)气象数据,分始播期、盛播期和终播期对各类型品种与区域热量资源进行定量匹配。【结果】适期早播可以争取162—230℃·d的积温。Ⅰ、Ⅱ、Ⅲ和Ⅳ类品种由播种至籽粒水分降至25%所需积温分别为3615、3291、3138和3427℃·d,在宁夏北部和中部区域所有类型品种均可满足含水率降至25%的要求,在南部山区,Ⅲ类品种在始播期和盛播期播种也能基本满足。4类品种籽粒水分降至16%所需积温依次为4321、3816、3633和4024℃·d,其中,早熟脱水快的Ⅲ类品种,在宁夏北部区域于始播期—终播期播种含水率均可降低至16%;在中部地区始播期和盛播期播种积温也可得到满足。【结论】在宁夏地区,通过合理配置区域热量资源和脱水类型不同的品种,采用早播种植技术,可以实现高质量的玉米机械粒收,其中,在宁夏北部与中部区域选择早熟、脱水快(Ⅲ类)的品种,可以较好地实现低水分收获,将区域热量资源转变为现实生产力。

【Objective】 In this study, the date when the kernel moisture content of different types of maize variety dehydrates to a suitable level for mechanical grain harvesting was predicted for different sowing dates in the Ningxia Hui Autonomous Region of China, in order to provide a basis for the variety selection at the regional scale, the determination of a suitable harvest period, and the development of the mechanical harvesting of maize varieties with a low moisture content. 【Method】Using the average kernel moisture content at physiological maturity(30.1%) and the average accumulated temperature(3 274.3 °C·d) required for sowing to physiological maturity ≥0 ℃·d as indicators, 38 common maize varieties were classified into four types by the two-way average method: type Ⅰ varieties were characterized by late maturity and slow dehydration;Type Ⅱ were characterized by early maturity and slow dehydration;type Ⅲ varieties were characterized by early maturity and fast dehydration;type Ⅳ varieties were characterized by late maturity and fast dehydration. According to the production practice in Ningxia, the varieties with medium kernel moisture content and accumulated temperature requirement at physiological maturity stage were selected as the representative variety of each type. Then, the Logistic Power nonlinear growth model was used to predict the dehydration of the 38 maize varieties base on 10 years of recent meteorological data(2008-2017). Based on these data, the kernel moisture characteristics of each type of variety were predicted for various regions of Ningxia with different heat resources for three different sowing dates(initial sowing,peak sowing, and initial sowing). 【Result】The results showed that, initial sowing could obtain an accumulated temperature of 162.2-229.8 °C·d in crop growth more than that of final sowing. The accumulated temperatures required for kernel dehydration to a moisture content of 25% from sowing for Type Ⅰ, Type Ⅱ, Type Ⅲ, and Type Ⅳ cultivars were 3 615.2, 3 290.6, 3 138.0, and 3 426.6 °C·d, respectively. In northern and central Ningxia, all types of varieties could meet the requirement that the kernel moisture content be reduced to 25%, while in the southern regions, Type Ⅲ varieties could meet the requirement that the kernel moisture content be reduced to 25% for sowing at the initial and peak sowing times. The predicted accumulated temperatures from sowing to dehydration required for kernel dehydration to a moisture content of 16% for Type Ⅰ, Type Ⅱ, Type Ⅲ, and Type Ⅳ cultivars were 4 320.6, 3 816.4, 3 632.9, and 4 023.6 °C·d, respectively. For the Type Ⅲ varieties, in northern Ningxia on the initial sowing date and final sowing date, the kernel moisture content of both could be reduced to 16%;in the central region on the initial sowing date and peak sowing date, the accumulated temperature required for dehydration to 16% could be satisfied.【Conclusion】 The heat resources of Ningxia could be used rationally through the selection of maize varieties with appropriate dehydration characteristics and early planting, thereby help to achieve high-quality mechanical maize kernel harvesting in this region. In northern and central Ningxia, it was recommended to select early-maturing, fast-dehydrating(Type Ⅲ) varieties in order to achieve the mechanical harvesting of maize with a low kernel moisture content and thus convert regional heat resources into economic benefits.