Teresa B. De Leon, School of Plant, Environmental & Soil Sciences, LSU Agricultural Center - Baton Rouge, Baton Rouge, LA, Prasanta K. Subudhi, Louisiana State University, Baton Rouge, LA, Steven Linscombe, Louisiana State University Agricultural Center, Rayne, LA and Glenn Gregorio, Plant Breeding, Genetics and Biotechnology, International Rice Research Institute, Manila, Philippines
In an effort to develop rice varieties with salinity tolerance, a study was conducted to assess the genetic diversity and tolerance of fifty rice genotypes to salt stress during seedling stage. The high yielding rice varieties developed for the rice growing regions of the southern states of the United States and rice landraces with wide range of salinity tolerance were obtained from the LSU Agricultural Center Rice Research Station and International Rice Research Institute. The plants were grown and evaluated in hydroponics salinized at a concentration of 12 dSm -1. Morphological, physiological and biochemical traits were measured to assess the degree of salt tolerance. Salinity tolerance of known cultivars was validated indicating the reliability of the evaluation technique. Correlation of quantitative traits indicated that chlorophyll reduction, shoot sodium-potassium ratio and shoot length reduction are positive and highly correlated to visual salt injury scoring while shoot potassium concentration is negatively correlated. Clustering based on these correlated quantitative traits effectively grouped the fifty genotypes into four major salinity classes. Moreover, principal component analysis based on 161 simple sequence repeat marker data showed major grouping of genotypes into indica and japonica sub-species with four minor groups. Among the uncharacterized rice genotypes, Geumgangbyeo was identified tolerant while LAH10 and R609 (MG) showed moderate tolerance. Pokkali and Nona Bokra are photosensitive; therefore, the use of Geumgangbyeo as a donor for salinity tolerance will be useful to the rice breeding program of Louisiana.