Abstract:
In Sri Lanka, iron toxicity is recognized as one of the most widespread soil constraints for rice
production, particularly in the low country wet zone. This paper investigates plant growth and yield
production resulting from iron toxicity in five rice varieties and two advanced breeding lines
cultivated on naturally iron-rich soils at the Regional Rice Research and Development Centre,
Bombuwala. The experiment was conducted in the 2017/2018 maha season. The randomized
complete block design with three replicates was used combing the seven treatments which included
three rice varieties and two advanced breeding lines of unknown iron tolerance, and a further two
varieties with known tolerant and susceptible traits. The susceptibility/tolerance to iron toxicity was
assessed using five endpoints indicating growth and yield production. Significant differences between
the seven exposed rice types were noted for all the recorded traits, with some showing superior
performances for selected traits. Taking each measured endpoint individually, the lowest leaf
bronzing score was recorded in Bw14-820, lowest number of days to 50 % heading in Bw272-6b,
highest number of tillers in Bw14-820 and maximum grain yield in Bg366. The tallest plants were
recorded in Bw267-3, although for paddy, a ‘moderate height’ is more desirable. Considering a
combination of the desirable traits i.e. with regard to all five recorded endpoints, the advanced
breeding line Bw14-820 and the variety Bg366 could be taken as showing the highest tolerance to
iron toxicity, suggesting that they could be recommended to overcome iron toxicity conditions in
lowland areas in the wet zone of Sri Lanka. These varieties could also be further used to develop more
tolerant strains of rice in future breeding programmes in the country.
