Abstract
The objective of this study was to assess the reliability of pot-based screening method for iron (Fe) toxicity tolerance in rice using soils from hot spots. Five lowland rice varieties with known reaction to Fe toxicity were grown in pots in a screen house for three seasons. Fe-toxic soils from two hot spot fields – Edozighi, Nigeria and Niaouli, Benin were used and soil from Africa Rice Center (AfricaRice) experimental farm, Cotonou, Benin was included as control. Leaf bronzing score (LBS) was determined at different stages, and grain yield was determined at maturity. Heritability was estimated using data across the three seasons. High heritability was recorded for LBS and grain yield. Grain yield reduction in stress treatment relative to control varied from 15 to 56% depending on the variety and soil. Bao Thai, Suakoko 8, and WITA 4 had better performance under Fe toxicity in terms of LBS, yield and relative yield reduction, whereas Bouake 189 and IR64 had poorer performance. Grain yield and LBS were significantly correlated but negatively at 60 days after sowing (DAS). Overall, the results found in this experiment were consistent with previous field studies. Therefore, pot screening using soils from hot spots can be used by rice breeding programs to reliably assess Fe toxicity tolerance ex situ.
Highlights
Fe toxicity is recognized as a widespread nutrient disorder affecting rice production in many inlands and swamps in West Africa (Abifarin, 1989; Chérif et al, 2009)
The Fe treatments significantly reduced grain yield on average, about 36% yield reduction was observed relative to the control
leaf bronzing score (LBS) was higher in the Fe-toxic treatment than in the control and the differences were significant at 40 days after sowing (DAS) and 60 DAS
Summary
Fe toxicity is recognized as a widespread nutrient disorder affecting rice production in many inlands and swamps in West Africa (Abifarin, 1989; Chérif et al, 2009). Bao Thai was grouped as highly susceptible to Fe toxicity based on hydroponic screening and later confirmed in field in Asia whereas grouping of all other varieties was based on field studies in African conditions (Table 1). Their characteristics in relation to the response to Fe toxicity were based on leaf bronzing score (LBS) and/or yield. The objective of this study was to assess the reliability of pot screening using soil from different Fe toxicity hot spots over three seasons and using five varieties with well-known Fe toxicity tolerance level in the field
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