Effects of Light and Air Temperature on Dry Matter Production of Ten Corn Varieties (Zea mays L.) at Early Growth Stage

[摘要] The effects of light and air temperature on early growth of ten corn varieties grown in pots were studied. Three levels of light intensity, i.e., 100, 75 and 45% of full sunlight were provided by shading in three different seasons of the year. (Table 1). The ten varieties used in this experiment can be divided into two groups with respect to their response to light intensity (Fig. 1). In the first group, crop growth rate (CGR) increased with light intensity from 45% to 75% of sunlight beyond which there was no further increase in CGR (light-saturated type). In the second group, CGR increased almost linearly with increasing light intensity up to 1OO% of sunlight (light-unsaturated type). In light-unsaturated type, development of leaf area (LA) increased with light intensity and the highest LA was showed at 100% of sunlight, but in light-saturated type, the highest LA was showed at 75% of sunlight (Fig. 2). Net assimilation rate (NAR) increased with light intensity in both types. CGR increased exponentially with air temperature from 14°C to 22°C under full sunlight condition (Fig. 3). The relationship between individual values of CGR and mean value of CGR in four varieties was analyzed by FINLAY and WILKINSON'S adaptability index method (Fig. 6). Variety Hokuyu, one of the light-saturated group, developed and cultivated in Hokkaido, the cool region of Japan, had higher values of CGR under low air temperature and low sunlight conditions than three other varieties. Under favorable environments, however, variety Ko No. 10, one of the light-unsaturated group developed and cultivated in Kyushu, the warm region of Japan, had much higher CGR than others. Hence, it was suggested that combination of the above two characteristics, high CGR under both unfavorable and favorable environments, would be most desirable for high yielding in the cool region.

[学科分类] 农业科学（综合）