Physiological and Ecological Studies on Corn Growth and Yield : IV. Optimum leaf area index for corn grain and dry matter production in relation to variety and soil fertility

[摘要] The leaf area index at silking time with relation to grain and dry matter production was examined on 2 corn varieties, Tomorokoshi Ko No.7 (varietal hybrid) and Yellow. Dent corn (open-pollinated variety), planted at 4 plant populations on the soils of 3 different fertility levels in 1967. The results are as follows. 1. Grain weight per LAI decreased as LAI increased and there was apparently a linear relationship between LAI and the logarithm of grain weight per LAI at each soil fertility level. The similar relationship was found between LAI and the logarithm of total dry matter weight per LAI in Tomorokoshi Ko No.7. From the relationships a method of estimating. optimum LAI at silkingtime to maximize grain and total dry matter yield was developed. 2. The optimum LAIs for grain production estimated by the method were 2.32, 3.76 and 4.91 for Tomorokoshi Ko No.7, and 2.51, 4.63 and 5.10 for Yellow Dent corn, at low, medium and high soi1 fertility levels, respectively. The optimum LAIs for the total dry matter production of Tomorokoshi Ko No.7 were 4.88, 5.34 and 6.85 at low, medium and high fertility levels, respectively. These results showed that the optimum LAIs for grain and total dry matter production increased as the soil fertility increased. 3. The flat LAI-grain yield curve near the optimum LAI suggested that near-maximum grain yields would be obtained in a wide range of LAI near the optimum LAI. 4. Tomorokoshi Ko No.7 possess an inherent capacity to produce grain weight per leaf area much more than Yellow Dent corn. 5. The optimum LAIs were larger in total dry matter production than in grain production. Therefore, it was suggested that larger LAIs with higher plant populations have an advantage in total dry matter production for silage.

[学科分类] 农业科学（综合）