RELIABILITY OF POT SCREENING METHOD TO EVALUATE FOR IRON TOXICITY TOLERANCE M. Sikirou1-2*, K. Saito1, A. Ahanchédé 2, K. Dramé1 and R. Venuprasad1 1Africa Rice Center (AfricaRice); 2Université d’Abomey-Calavi Introduction Results Iron toxicity is recognized as a major constraint of rice production in many inlands and swamps in Africa. Excessive amounts of Fe2+ due to ferric iron reduction in anaerobic conditions at low pH leads to accumulation by transpiration and cause yield losses from 20% to 100%. The main characteristic of fe-toxicity is bronzing. The most cost effective approach to overcome the problem of iron toxicity is the use of iron toxicity tolerant rice varieties. Breeding for iron toxicity is slow due to lack of reliable screening method. Breeding programs rely on hotspot screening but field hotspot screening is affected by several variable factors and often results in poor heritability. Some groups have used pot screening method in which soil from an iron toxic field is used. However, reliability of this method is not known. We studied the efficacy of pot screening for iron toxicity tolerance using hotspot soil from two countries. The results of the study are discussed. Sensitive and tolerant varieties differed significantly in their leaf bronzing scores and yield. WITA 4 and IR64 were the best and worst lines under iron toxicity conditions respectively. Bao Thai was not susceptible in African conditions both in pot and fields. Leaf bronzing score were much severe in 2013 than in 2012. Heritability of leaf bronzing score and yield was 0.76 and 0.78 respectively. Significant negative correlation between yield and leaf bronzing score was observed (Fig. 3). High correlation between leaf bronzing scores in field and in screen house was observed (Fig. 4). Leaves reached Score 7 Table 2:Treatments characteristics Treatments Iron content pH T1: non toxic Soil + tap water 120.38 5.2 T2: Soil Edozighi + tap water 152.24 4.8 T3: Soil Niaouli + tap water 205.85 4.6 T4: Soil Niaouli + water from Niaouli 208.1 4.5 Materials and Methods Experiment was conducted at AfricaRice screen house at Cotonou during 2012-13. Soils were brought from iron toxic fields at Edozighi (Nigeria) and Niaouli (Benin). Soil from Cotonou, Benin was used as control. Five varieties with known reaction to iron toxicity (Table 1) were grown in pots. The experiment consisted of four treatments (Table 2). Data on agronomic traits and leaf bronzing score were recorded. Performance of these lines in pots were compared against the performance in two hotspots in Burkina Faso and Liberia. Table1: Origin and characteristics of varieties Name Reaction to iron Origin Duration (Days) Bao Thai Sensitive Vietnam 130 Bouake 189 Ivory coast 125 IR 64 IRRI Philippines 120 Suakoko 8 Tolerant Liberia 150 WITA 4 Nigeria A B Conclusions Screenhouse set-up with RCD design Pot screening with fe-toxicity soil is simple, reliable and cost effective This method could be used for characterize donors, parents and most advanced breeding lines The method can be extended to screen larger population but needs significant investment Acknowledgements Contact Information Name : Venuprasad Ramaiah Email: R.Venuprasad@cgiar.org Organization: AfricaRice Tel: +234 8031945034 Theme 1: Climate resilient rice for Africa’s environments and markets