Genotypic variation in rice tolerance to iron toxicity: insights from Bangladesh

M.R. Islam¹*, N. Akter¹, S.F. Ahmed², R.B. Rupok¹ and M. Akter¹

¹Department of Agronomy, Faculty of Agriculture, Gazipur Agricultural University, Gazipur-1706, Bangladesh
²Department of Crop Botany, Faculty of Agriculture, Gazipur Agricultural University, Gazipur-1706, Bangladesh
*Correspondence: rafiarib@yahoo.com

Abstract:

Iron (Fe) toxicity is a major abiotic stress affecting rice production, particularly in acidic soils. Although not well-documented in Bangladesh, Fe toxicity is becoming a significant agronomic concern due to rising concentrations in irrigated soils. This study aimed to assess the tolerance of 18 rice genotypes to Fe toxicity stress based on morphophysiological and yield-related traits. A pot experiment was conducted at Gazipur Agricultural University, Gazipur, using a completely randomized design with three Fe levels: control (0 mg L⁻¹), Fe₁ (600 mg L⁻¹), and Fe₂ (1,200 mg L⁻¹). Results showed that increasing Fe²⁺ concentrations significantly affected plant height, tillering ability, chlorophyll content, and grain yield. At Fe₂, total tillers per hill declined by 65.8%, and effective tillers reduced by 35.5% compared to the control. Panicle length and the number of filled grains decreased, while unfilled grains increased, indicating reproductive stage Fe stress. The SPAD chlorophyll index declined by 21.3% under Fe₂, reflecting Fe-induced chlorosis. Grain yield exhibited a sharp reduction of 46.3% under Fe₂, highlighting the detrimental impact of Fe toxicity on productivity. Genotypic variations were observed, with BU line 5 exhibiting the highest grain yield (0.92), effective tillers hill^-1 (0.89), and lowest unfilled grains per panicle (1.26), suggesting superior tolerance. Multivariate analysis grouped genotypes based on the stress response, identifying BU line 5, BU line 13, and BRRI Dhan 28 as promising Fe-tolerant candidates. These findings highlight the critical need to breed Fe-tolerant rice varieties to mitigate yield losses in Fe-affected soils. Further research on the genetic and molecular mechanisms of Fe toxicity tolerance will facilitate breeding programs for stress-resilient rice varieties, ensuring food security in regions prone to Fe toxicity stress.

Key words:

chlorophyll index, iron toxicity tolerance, Multivariate analysis, rice genotypes, yield