Elucidating the Response of Rice Genotypes to Iron Toxicity through Hydroponics

Iron (Fe) toxicity is a major abiotic stress that impedes rice cultivation in many lowland environments worldwide. Although several cultural and management practices are advocated to address this problem, the best and most economic approach to combat this issue is the use of tolerant cultivars. The present study was aimed at elucidating the response of rice genotypes, including local landraces and released varieties to iron toxicity by screening seedling growth in a hydroponic solution containing varying levels of iron. The increasing concentration of iron had significant effect on all characters studied and the severity of symptoms. Significant difference was also observed for concentration × variety interaction for all the characters studied except root and shoot length of the seedlings. Increase in root number was observed at 600 ppm, indicating the repair mechanism of the plants against edaphic stress beyond the threshold level. Varsha, a mid-early, high yielding red-kernelled rice variety and Chuvannamodan, an indigenous landrace of Kerala, showed tolerance to high concentration of iron (> 600ppm), among the ten genotypes screened. It can be inferred that evaluation of genotypes at 600 to 800ppm concentration of iron in a hydroponic solution is a quick and efficient methodology to delineate the tolerance of rice genotypes to iron toxicity.