Response of Rice (Oryza Sativa L.) to Short-term High Temperature: Growth, Development, and Yield

Abstract

Effects of short-term high temperature occurring in the vegetative and the grain-filling stages on growth, development, and yield of rice (Oryza sativa L. cv. Lemont) were studied in the controlled environment. The results showed that an 8-d 35℃ treatment at the vegetative stage changed the growing patterns of plant height, total leaf and tiller numbers, and leaf area relative to a 25℃ treatment. Plant elongation was reduced for 50 days after treatment. Leaf and tiller production were also restrained, though the tillering rates for the 35℃-treat ed plants eventually caught up to those for the 25℃-treated ones in about 70 days after treatment. Leaf area expansion was restricted by high temperature; growth of primary leaves 8 to13 was inhibited. Both leaf length and leaf width were affected. Plant development, in terms of leaf stage, was little affected by temperature treatments in the vegetative stage. Data showed no differences between treatments in the measured yield characteristics. High temperature had little effect on plant height after heading in the grain-filling stage while leaf growth and tillering were stimulated. The panicle numbers per plant increased but spikelets per panicle, percent filled spikelets, and 1000- grain weight decreased as a result of high temperature. The shoot/root weight ratio was elevated by heat stress in the vegetative stage but was decreased by heat stress in the grain-filling stage.