Mudalige, H.M.M.Y.Masakorala, K.2025-11-132025-11-132021-10-29Proceedings of the Postgraduate Institute of Science Research Congress (RESCON) -2021, University of Peradeniya, P 28978-955-8787-09-0https://ir.lib.pdn.ac.lk/handle/20.500.14444/6563Iron toxicity is one of the widely distributed nutritional disorders that affect rice production negatively. Therefore, the identification of efficient biomarkers for screening rice varieties with tolerance to excess Fe²⁺ is important. However, leaf bronzing has been widely used as a phenotypic biomarker in screening rice varieties against Fe²⁺ toxicity. Hence, this study aimed to investigate the applicability of chlorophyll content and peroxidase activity (POD) as biomarkers for screening rice varieties against iron (Fe²⁺) toxicity. Two rice varieties recommended for the low-country Wet Zone (LCWZ) of Sri Lanka were identified as iron tolerant (Ld408) and susceptible (Ld365) by the initial study before being used in the experiments. Seven-day old seedlings of both varieties were exposed to different levels of Fe²⁺ [150 mg L⁻¹ (Control), 450 mg L⁻¹ , 650 mg L⁻¹ , 850 mg L⁻¹ , 1,050 mg L⁻¹ and 1,250 mg L⁻¹ ] at pH 5.5 for seven days. A randomized block design (RBD) was employed with three replicates per treatment and control, and the experiment was carried out in a modified flood and drain hydroponic system. At the end, the total chlorophyll content and POD activity were measured. All data were analyzed through two-way ANOVA followed by Tukey’s posthoc test using the statistical software MINITAB 17. Ld408 showed Fe²⁺ level-dependent significant (p < 0.050) increase in the total chlorophyll content and POD activity with the increase in Fe²⁺ concentration. In contrast, Ld365 indicated a significant reduction (p < 0.050) in the total chlorophyll content and POD in the treatments with the Fe²⁺ concentration higher than 450 mg L⁻¹ and 650 mg L⁻¹ , respectively. Further POD activity of Ld408 showed a lower rate in all treatments compared to Ld365. The observed decreases in the chlorophyll content and increasing POD activity of Ld365 infer that the exposed plants to Fe²⁺ treatments are under the stressful condition compared with plants of Ld408 under the same treatments. The overall results indicate the variety-specific sensitivity of both chlorophyll content and POD towards Fe²⁺ concentration, highlighting higher tolerance of Ld408 than Ld365 for the excess Fe²⁺ . According to our preliminary data, it may be possible to apply total chlorophyll content and peroxidase (POD) activity as biomarkers for screening tolerant rice varieties to Fe²⁺ toxicity at the early growth stage.en-USChlorophyllIron toxicityLd365Ld408Peroxidase activityArticle