Screening of Selected Rice Varieties and Advanced Breeding Lines against Iron Toxicity under Field Conditions in the Low Country Wet Zone of Sri Lanka

Abstract

Iron toxicity is one of the most commonly observed soil nutritional disorders, which causes lowering of rice yields, especially in the low country wet zone (LCWZ), Sri Lanka. A field screening experiment was conducted in 2017/2018 Maha at regional Rice Research and Development Centre (RRRDC), Bombuwala, Sri Lanka. A site known for its relatively high iron levels was selected for this study. Thirteen rice varieties (eleven new improved and two traditional rice varieties), six advanced breeding lines, four Fe tolerant varieties and a susceptible variety (control) were used. Iron toxicity was scored on a 0 to 9 scale according to standard evaluation system for rice developed by International Rice Research Institute (IRRI) for four growth stages of plants. In addition, soil samples were collected from selected field for physical and chemical analyses. Soil Fe concentration in rice fields ranged from 474.4–1204.7 mg/kg, which was within the range that could induce toxic effects in rice plants. The degree of leaf bronzing varied significantly across different varieties/lines and in different stages of growth in a single variety/line. Overall results showed that Bg 366, Bg 300 (newly improved rice variety), Madathawalu (a traditional rice variety), BW 14-820 and BW 13-3-1184 (advanced breeding lines) were highly tolerant to Fe toxicity in all four growth stages. Present study emphasized that varieties/lines tolerance to iron toxicity could be cultivated in iron toxicity prevailing soils in LCWZ and used as parental materials in future rice breeding programs in Sri Lanka.