Youssef Trifa

Comparative performance of δ13 C, ion accumulation and agronomic parameters for phenotyping durum wheat genotypes under various irrigation water salinities: Triticum durum, salinity, stable carbon isotope, nitrogen concentration

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 (δ¹³Cgᵣₐᵢₙ) 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, 6 dS m⁻¹), Barrouta (S2, 12 dS m⁻¹) and Sidi Bouzid (S3, 18 dS m⁻¹). GY was shown to be negatively correlated to Ngᵣₐᵢₙ as well as to δ¹³Cgᵣₐᵢₙ. This is confirmed by a multiple linear regression analysis that showed that both δ¹³Cgᵣₐᵢₙ 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 δ¹³Cgᵣₐᵢₙ. 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 δ¹³Cgᵣₐᵢₙ can be used for an efficient screening of salt tolerant durum wheat. Under our experimental conditions, Ngᵣₐᵢₙ was shown to be highly correlated to δ¹³Cgᵣₐᵢₙ and can therefore be easier‐to‐use trait to assess the tolerance to salinity.