Abstract In sub-Saharan Africa, projected climate change is expected to reduce rice productivity as a result of excessive light exposure and prolonged flooded conditions that favor soil iron reduction and accumulation. Excess iron (Fe), which commonly accumulates in poorly drained rain-fed fields across the region, hinders rice growth. Conversely, excess light causes photoinhibition. While Fe toxicity disrupts plant growth, its interaction with light intensity remains poorly understood. NERICA4, an interspecific rice hybrid between Oryza sativa and Oryza glaberrima , a widely cultivated upland rice variety, is recognized for its tolerance to Fe; however, its response to the combined effects of Fe toxicity and varying light intensity has not been thoroughly investigated. This study aimed to assess the responses of agricultural traits of NERICA4 under simultaneous Fe toxicity and different light intensities. A controlled hydroponic experiment was carried out using a completely randomized design with three replications. Seedlings of NERICA4 and IR64 were exposed to either control or excess Fe (750 mg L −1 ) under both low (450 μmol m −2 s −1 ) and high (700 μmol m −2 s −1 ) light conditions for 12 days. Results revealed that NERICA4 maintained higher biomass, restricted Fe translocation, and showed reduced oxidative damage, as evidenced by lower hydrogen peroxide (H 2 O 2 ) accumulation. Furthermore, the variety preserved greater chlorophyll and carotenoid content, supporting enhanced photoprotection and antioxidative defense. Despite stress conditions, NERICA4 sustained photosynthetic efficiency (Fv/Fm), reflecting robust adaptive mechanisms against photoinhibition. These findings demonstrate that NERICA4 exhibits superior tolerance to combined excess iron and high light stress compared to IR64, maintaining photosynthetic and antioxidant defense. This highlights NERICA4’s potential as a resilient rice variety for cultivation under challenging agro-environments.
Chepkoech et al. (2026) studied this question.