Response of some upland rice varieties to drought stress examined using Polyethylene Glycol and water applications

Abstract

Abstract. Purwanto E, Samanhudi, Yoniar Effendi Y. 2017. Response of some upland rice varieties to drought stress examined using Polyethylene Glycol and water applications. Trop Drylands 1: 69-77. The utilization of drought-resistant rice varieties cultivated in upland areas is necessary to increase rice production. One method employed to screen drought-resistant upland rice genotypes is by screening the available germplasm using a solution with high osmotic pressure such as PEG (Polyethylene Glycol). The study aimed to examine the response of upland rice varieties at germination stage on several PEG 6000 concentration levels and to determine growth characteristics, physiological changes, and yield of upland rice varieties under drought stress conditions in a pot experiment. The study consisted of two laboratory experiments; the first was to study germination and early growth, and the second was to study the vegetative and generative growth of upland rice under drought stress conditions. Experiments I and II were conducted in a completely randomized factorial design consisting of two factors and three replications. In experiment I, the first factor was upland rice variety comprised of 10 varieties and the second factor was PEG concentration consisted of four levels. In experiment II, the first factor was upland rice varieties that responded the best to drought stress in experiment I, and the second factor was the drought stress treatment consisting of moisture content at 100, 75, 50 and 25% field capacity. The results showed that the germination and vigor index decreased with increasing levels of PEG concentration. PEG concentration of 25 g L^-1 of water was the most optimum for screening drought-resistant upland rice. In experiment I, Towuti, Situ Patengang, Kalimutu and Gajah Mungkur varieties showed the best response to drought stress. Increased intensity of drought stress resulted in a reduction of plant height, number of tillers, dry weight, relative growth rate, leaf area, number of grains hill^-1, 1000 grain weight, dry grain weight hill^-1 and root dry weight. The drought stress also caused an earlier flowering date and an increased percentage of empty grain. Based on the dry grain weight hill^-1, Towuti exhibited a higher drought resistance level than Gajah Mungkur, Situ Patenggang and Kalimutu.