Abstract:
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.
