Optimization Measures For Maize (Zea Mays L.) Based On Light, Temperature, And Precipitation Resources In Northeastern, China

Objectives: Light, temperature, and precipitation are key ecological factors affecting crop growth. These factors show great variation in northeastern China, providing an opportunity to study the relationship between ecological factors and crop growth. This study was undertaken to assess the optimal conditions for maize production and to provide reference values for other locations. Methods:An analysis of meteorological data collected between 1951 and 2014 in the spring maize area of northeastern China was conducted. Ten maize varieties were subjected to different experimental treatments(sowing date, planting density, and water application) to examine their responses to variations in light, temperature, and water. Optimal countermeasures for maize production were determined based on resource restrictions in the spring maize area of northeastern China. Results: The main results of the study are as follows:1. Global warming has altered the distribution of the maize belt in China, especially in the spring maize area of northeastern China. The mean air temperature has increased by 1.34°C since the 1950 s, and the active accumulated temperature above 10°C has increased by about 277°C since the 1950 s. Heilongjiang Province showed the greatest sensitivity to these temperature changes; the sowing date for maize is 5 days earlier than it was 50 years ago. Overall, these temperature increases have altered the areas in which maize is cultivated; for example, a new plan for planting maize has been created in Heilongjiang Province. Additionally, the varieties planted may need to be adjusted.2. Using an optimal planting density is important in improving maize yields. However, the optimum planting density in an area must be based on the maize variety and ecological factors. To take full advantage of the light interception and radiation use efficiency of maize growing in northeastern China, information about suitable planting densities is needed. The results of this study show that light radiation increased from east to west in the spring maize area of northeastern China and that the optimal density for varieties restricted by light radiation was increased. However, the most appropriate planting density was different for each variety; thus, the optimal density must be based on the specific situation.3. Water plays a key role in net primary productivity. The carrying capacity of local water resources also has an important influence on maize. Our data indicate that precipitation in the spring maize area of northeastern China decreased from east to west, as did the carrying capacity of the water resources. The results of this study indicate large differences among the maize varieties examined; the lowest average water use efficiency(WUE) was 1.5, the median WUE was 1.75, and the highest average WUE was 2.2. A close relationship was detected between the WUE of each variety and the planting density. Thus, the planting density of maize can be improved by selecting varieties with high WUE. This study determined the optimum planting density of maize varieties in different areas based on precipitation, evaporation, and WUE.4. The most reasonable planting density for maize was analyzed according to the light, temperature, and water resources in the area, as well as the adaptions of each variety. The factors affecting the ideal maize planting density varied across different areas of northeastern China; light radiation was a limiting factor in the east, precipitation was a limiting factor in the west, and temperature was a limiting factor in the north. Large differences in the most suitable cultivar, planting density, and countermeasures were detected among the areas examined. These results will provide a reference for maize production in northeastern China. Conclusions:To take full advantage of the available light, precipitation, and temperature resources in maize-producing areas, appropriate countermeasures must be considered. This study indicates the most suitable variety, sowing date, and planting density to facilitate optimal maize production based on an accurate analysis of ecological factors in northeastern China.