Developmental differences in rice plants in relation to photoperiodism.

Abstract

Two varieties of rice sensitive to the length of photoperiod, Nero di Vialone and Kameji, and 2 insensitive varieties, Fortuna and Karang Serang, were subjected to daily photoperiods of 12 and 18 hr. applied either throughout the growing period or at various stages of the growing period. Earlier formation of panicles was induced by 12 hr. than by 18 hr. photoperiods in the case of Nero di Vialone and Kameji, but not in the case of Fortuna and Karang Serang. Where early flowering was induced by the use of 12 hr. photoperiods the panicles on the main stem were smaller than corresponding panicles on plants grown with 18 hr. photoperiods. The length of photoperiod had no direct influence on the growth of leaves. In the case of the sensitive variety Nero di Vialone, all tillers subjected to 12 hr. photoperiods from the beginning of growth entered the reproductive stage, after which a proportion of them ceased development, whereas a proportion of the tillers subjected to 18 hr. photoperiods from the beginning of growth ceased development before they had formed an inflorescence. A change from 12 hr. to 18 hr. photoperiods in sensitive varieties at the time of initiation of inflorescences caused a delay, and a change from 18 hr. to 12 hr. photoperiods, a hastening, of the subsequent development of flowers. The morphological characters of the axillary buds of rice plants at various stages of growth are described.-W.J.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)