Comparative performance of [delta]13C, ion accumulation and agronomic parameters for phenotyping durum wheat genotypes under various irrigation water salinities

The use of efficient selection traits for screening under contrasting irrigation water salinity is a challenge for breeders. To identify patterns, grain yield (GY) and yield components (kernels m-2, thousand kernels weight), growth traits (plant height, biomass), flag leaf ion accumulation (Na+ and K+), carbon isotope composition ([delta]13Cgrain) and nitrogen concentration (Ngrain) of grains were assessed on 25 durum wheat genotypes (G) in two consecutive growing seasons (2010 and 2011), in three semi-arid locations in Tunisia. Each location differed in their irrigation water salinity as measured by electrical conductivity: Echbika (S1, 6dSm-1), Barrouta (S2, 12dSm-1) and Sidi Bouzid (S3, 18dSm-1). GY was shown to be negatively correlated to Ngrain as well as to [delta]13Cgrain. This is confirmed by a multiple linear regression analysis that showed that both [delta]13Cgrain and Ngrain were the major determinant components for GY variability under S3. A high genotypic variability was observed and the improved genotype Maali exhibited the most stable GY under the three irrigation water salinities and the two cropping seasons. Maali showed the lowest [delta]13Cgrain. This indicates that tolerance in durum wheat is likely to be correlated to the ability of maintaining a high stomatal conductance. According to our data suggests [delta]13Cgrain can be used for an efficient screening of salt tolerant durum wheat. Under our experimental conditions, Ngrain was shown to be highly correlated to [delta]13Cgrain and can therefore be easier-to-use trait to assess the tolerance to salinity.