Effect of iron (Fe²⁺) toxicity on yield and yield components of selected high-yielding rice varieties under low country wet zone field conditions

De Silva SR¹, Masakorala K^1*, and Withanawasam DM²

¹Department of Botany, University of Ruhuna, Matara, Sri Lanka
²Regional Rice Research and Development Centre, Department of Agriculture, Bombuwala, Sri Lanka

Abstract

Iron (Fe²⁺) toxicity is a significant nutritional disorder that reduces rice yields, particularly in Sri Lanka's Low Country Wet Zone. This study aimed to assess the effects of Fe²⁺ toxicity on grain yield and yield components of selected high-yielding rice varieties and analyse their sensitivity to iron toxicity by comparing yield and yield-related parameters obtained under iron stress treatment with those recorded under control conditions. A field screening experiment was conducted during the 2023–2024 Maha season at the Regional Rice Research and Development Centre, Bombuwala, Sri Lanka using 15 rice varieties (BW272-6B, Bg359, BW372, BW302, At311, BW266-7, BW312, BW361, Bg300, BW367, BW364, BW267-3, BW363, Bg374, BW51). A site with high Fe²⁺ levels (294.45 to 317.10 mg kg^-1) was selected to induce toxic effects, while a control site had low levels (78.90 to 112.63 mg kg^-1). To evaluate the effect of iron toxicity on grain yield and yield components of 15 rice cultivars, a randomized complete block design (RCBD) with 3 replicates (n=3) was used. Grain yield per plant, along with plant height, tiller number, 1000 grain weight, and fertility (filled and unfilled grains per panicle), were recorded as yield components. A Generalized Linear Model was employed to assess the effects of treatment, variety and their interaction on yield and yield parameters. The results showed that BW267-3, BW367, BW363, BW372, BW302, and At311 had no significant differences in yield and yield components compared to the control, indicating high tolerance to Fe²⁺ toxicity. Conversely, BW272-6B and Bg359 showed significant reductions in yield (33%), 1000-grain weight (40%), fertility (25%), plant height (18%), and tillering (33%), thereby classifying them as susceptible. Other varieties were moderately affected and classified as moderately tolerant.

Keywords: Field screening, High-yielding rice varieties, Iron toxicity, Susceptibility, Tolerance

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Faculty of Agriculture, University of Ruhuna, Mapalana, Kamburupitiya, Sri Lanka

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