Response of 16 rice varieties (Oryza sativa L.) to high temperature at vegetative stage

Abstract

16 rice varieties (Oryza sativa L.) were evaluated for their tolerance to heat stress up to 8 weeks after planting. The rice varieties consisted of drought tolerance rice varieties, black rice varieties, low-land varieties, and commercial varieties. The experiment was arranged using a split plot design with temperature as a main plot and a rice variety/accession as a sub plot with three replications. The treatment for high temperature consisted of actual temperature in the screenhouse (N1), the temperature above 38oC (N2), and above 40oC (N3) at mid-day. The average temperature and humidity for N1, N2, and N3 at noon was 36.4oC and 67%, 38.9oC and 60%, and 41.6oC and 45%, respectively. The result showed that heat stress affected plant height, tiller number per plant, leaf number per plant, shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, and root number per plant. There was also significant difference between the tested varieties on plant height, tiller number, leaf number, shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, and root number per plant. The interaction between high temperature and variety was significant on plant height, tiller number, leaf number, root fresh weight, and root dry weight. Jaliteng and Situbagendit had the highest tiller number and leaf number under N3 condition (above 40oC at the mid-day).