1. 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 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
Organization: AfricaRice
Tel:
Theme 1: Climate resilient rice for Africa’s environments and markets