Screening and selection of drought-tolerant rainfed lowland rice seedlings based on early seedling vigor under Polyethylene Glycol-Induced Stress

Abstract

A field-based drought tolerance screening is time- consuming and labor-intensive. Polyethylene Glycol (PEG) offers a simple laboratory-based method to simulate drought stress efficiently. This study was conducted to identify and select the five most drought- tolerant genotypes based on vigor-related traits under PEG-induced drought stress. These genotypes will be used in a subsequent study involving greenhouse and molecular screening for drought tolerance. Responses of 23 rainfed lowland rice (Oryza sativa L.) genotypes subjected to varying drought levels were investigated in two trials under laboratory conditions to evaluate against three drought levels (0MPa, -0.5MPa, 1MPa) at germination and early seedling growth stage of plant development. Germination percentage and rate, root length, seedling vigour index, root and shoot dry weight were gathered. Data from two trials were combined and analyzed statistically for all growth parameters obtained. Experimental units were arranged in factor factorial in RCBD with 3 replications. Results showed that all parameters gathered except for root-shoot ratio were significantly affected by the levels of PEG, genotypes and their interaction. The five drought-tolerant lines; AL-108, AL-87, AL-97, AL-55, AL-5 tolerated PEG-induced stressed at the highest drought level (-1MPa) and showed no significant difference with unstressed (0MPa) based on seedling vigour. AL52 and NSIC Rc82 were markedly affected at the highest PEG level (-1MPa) and hence considered as drought-sensitive.