Growth, Development and Yield of Rice in Response to Cold Temperature

Abstract

The effects of duration of cold, varying from 1 to 15 days, at 15/10 °C day/night temperature, were examined at floral initiation and booting in three cultivars of rice which differed in sensitivity to cold. Cold durations of greater than 1 day reduced spikelet number (up to 41 %), spikelet fertility (up to 90 %), inflorescence branch number (up to 43 %) and total length of branches (up to 34 %) relative to controls. Cold reduced spikelet number more than fertility at floral initiation, whereas cold reduced fertility more at booting. Some processes of growth — inflorescence branching, spikelet development, and dry matter accumulation — were directly and irreversibly damaged by cold. On the other hand, apex elongation showed thermal retardation (defined as a reduction in growth rate during the period of cold, only to the extent predicted from reduced thermal time) but recovered after cold was relieved. The sensitivity of a particular physiological process to cold may be related to the ability of the rate of that process to recover from cold stress and the opportunity (after cold stress is removed) for the completion of growth before the end of a development phase.