A maximin-minimax approach for identifying drought tolerant genotypes based on yield potential and loss in durum wheat

Drought is the major cause of durum wheat yield losses in the Mediterranean and many other regions where the crop is not normally irrigated. Over three years (2010–13), 24 durum wheat genotypes representing diverse genetic materials were tested under drought and irrigated conditions. The main objectives were to assess the degree of genotypic variation for drought tolerance, characterize genotypic differences in response to drought, and identify sources of germplasm with greater drought tolerance than old and new cultivars. The percent reduction in average grain yield under drought conditions as compared to irrigated conditions was maximum (69%) during 2012–13, followed by 2010–2011 (33%) and 2011–2012 (15%). The average yields of genotypes under drought conditions differed significantly, which ranged from 1174 (correspond to old variety) to 2086 kg/ha (correspond to breeding line G2). The maximin-minimax approach, yield tolerance index (YTI) and three-dimensional (3-D) plot were used to classify genotypes for drought tolerance and yield productivity. Based on the results, two genotypes were identified as resistant and high yielding (G3 and G20), and eight genotypes (G2, G22, G8, G11, G15, G1, G9 and G5) were found to be high yielding and tolerant to drought conditions. Among the methods, the maximin–minimax approach appears to be more useful in identifying high yielding and drought tolerant genotypes as it seeks to minimize percentage yield loss while maximizing yield potential. In conclusion, considerable variability in yield and drought tolerance was observed for the durum wheat genotypes, which could be exploited at improving drought tolerance in durum wheat breeding program