Growth responses of genetically diverse rice (Oryza sativa L.) cultivars to Arsenic stress

Abstract

Although arsenic (As) is a toxic element for plant growth, it can accumulate in rice plants to higher levels. A case-control experiment was carried out to investigate the impact of As in soil on rice plant growth. Nine (9) different native and improved rice cultivars were grown in soils with 10 mg/kg As. Total As content in grains was quantified using an ICP-MS. The mean As content in control samples was 15.8 µg/kg while As treatment samples showed 122 µg/kg. Grains of improved rice variety of Bg 300 showed the highest As accumulation. The chlorophyll content declined by 28% under As stress and 56% tiller losses were also observed. The significant reduction of plant growth has given an impaired grain yield under As-treated conditions. Soil arsenic also showed a significant impact on Ni, Rb, and Ba uptake and accumulation. This study showed that As accumulation in rice is cultivar-dependent and also indicated a drastic reduction of the yield under elevated As levels. The native cultivar, Kahawanu was shown the lowest As-accumulation (90.1 mg/kg) under elevated As within the nine rice cultivars. So it can be identified as the best resistance cultivar for the As stress. The results can be utilized for developing high-tolerance rice varieties using new breeding technologies.