Ecological Studies on Vegetative Growth in Rice Plants : 1. On the leaf emergence interval

Abstract

The experiment was performed to find some regularity on the changes of day intervals required for the emergence of each consecutive leaves on the stem of rice plants. As experimental materials, some varieties of rice plants were grown in Wagner pots with soil or water media, by direct sowing method. The results obtained are as follows: 1) The day intervals required for each leaf emergence on the main stem differed according to the growth stages of the plants. Namely, the intervals at the early growth stage (earlier than 7 th leaf-age) were short and hardly differed among each leaf, then, became gradually longer as the growth stages advanced. And the intervals became longest at 1 st or 2 nd leaf below the bootleaf, the intervals of which were a little shorter than those of its predecessors. 2) Therefore, the changes of the day intervals through out the growth period might be divided into three periods. These periods could be considered from a different view of the plant growth, that is, the first period meight be corresponded to the most vigorous growth period of tillers, the second period to the one when tillering is unstable or almost none and the third period to the reproductive period of the plants. 3) The day intervals of the tillers were a little shorter than those of the main stem. But, wherever tillering might occur, the changes of day intervals of tillers caught up the very trends of the main stem after the emergence of 1 st or 2 nd leaf. 4) In regard to varietal difference of the intervals, no clear difference was found except for the 1 or 2 leaves below the boot-leaf.