Preliminary responses of some Thai rice cultivars to simulated acid rain stress during seed germination

Abstract

Germination response of nine Thai rice (Oryza sativa) cultivars was investigated under simulated acid rain at pH values of 2.5, 3.5, 4.5, 5.5 and a control at pH 6.5 using a split-plot in completely randomized design (CRD) with three replications as main plots and subplots. Germination percentage, seedling characteristics and inhibitory responses were evaluated. Results showed that rice seed germination decreased after exposure to simulated acid rain of pH 2.5, 3.5 and 4.5 compared to the control. Acid rain significantly decreased seedling root length, root-to-shoot ratio and crown roots per seedling while pH 2.5 completely inhibited all the investigated seedling characteristics. Average values of germination percentage reduction were highly significant in KDML105 and RD27 cultivars while acid rain stimulated rice seed germination in HPYTD, RD57, MLL and TTCP, suggesting that these cultivars are tolerant to acid rain stress during seed germination. This research was partially supported by the Center for Advanced Studies for Agriculture and Food, Institute for Advanced Studies, Kasetsart University under the Higher Education Research Promotion and National Research University Project of Thailand. The authors would like to thank the Center for Advanced Studies for Agriculture and Food (CASAF), Kasetsart University, Bangkok, Thailand for financially supporting this Post Master Research Project and the Central Laboratory and Greenhouse Complex of the Faculty of Agriculture, Kasetsart University, Bangkok, Thailand for laboratory instrument support.