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.
