The Effect of Different Planting Date on Growth of Zea mays L. : I. On growth and fresh weight increase of corn plants from seeding to tasselling under dense spacing.

Abstract

Four corn varieties, each representing early, medium and late maturity were sown respectively at various times from April 30 to August 5, and their fresh weight was investigated in 1959 and 1960 at the kikyogahara Branch of Nagano Agricultural Experiment Station. The results obtained were as follows: 1. Fresh weight of early maturing variety planted somewhat late is comparatively heavier than that planted at the other dates. While, fresh weight of late maturing variety planted earlier is heavier than that planted at the other dates. Increase in culm length shows a tendency similar to that of fresh weight throughout the growth period. In this respect, medium maturing variety shows the intermediate tendency between those of early and late maturing varieties. 2. Days from emergence to tassel differentiation are less in the cases of later planting. The time of tassel differentiation of early maturing variety is earlier than those of later maturing ones. The tassel of early variety initiates before the lowest internode begins to elongate. The duration of the lowest internode elongation is constant among varieties, if they are seeded at the same time. 3. Days from emergence to tassel differentiation or to the time of the lowest node elongation are affected by mean temperature and are scarcely affected by day length during the course of plant growth. 4. The fresh weight at the time of young tassel formation is varied according to planting time and also to varieties. 5. Fresh weight of plants during the time from the lowest ioternode elongation to tasselling is affected by temperature in the case of early maturing variety, while those of the medium and late maturing variety are affected by day length as well as by temperature. Extreme late maturing varieties are affected mainly by photoperiod. The earlier the tassel differentiation begins the less fresh weight is. 6. In early maturing variety, the degree of elongation of the lower internodes is remarkable when planted somewhat late. When planted extremely late, the elongation of the upper internode is inhibited by low temperatre and the number of nodes decreases. The elongetion rates of upper internode ate affected ramarkably by low temperature in the case of late maturing varieties planted rate, while the elongation of lower internode is promoted in the preceeding warm condition. Therefore in later maturing variety, the culm length of earlier planted one is longer than that of later planted one.