Effect of salinity and water stress during the reproductive stage on growth, ion concentrations, Δ13C, and δ15N of durum wheat and related amphiploids

Abstract

The physiological performance of durum wheat and two related amphiploids was studied during the reproductive stage under different combinations of salinity and irrigation. One triticale, one tritordeum, and four durum wheat genotypes were grown in pots in the absence of stress until heading, when six different treatments were imposed progressively. Treatments resulted from the combination of two irrigation regimes (100% and 35% of container water capacity) with three levels of water salinity (1.8, 12, and 17dS m-1), and were maintained for nearly 3 weeks. Gas exchange and chlorophyll fluorescence and content were measured prior to harvest; afterwards shoot biomass and height were recorded, and Δ13C, δ15N, and the concentration of nitrogen (N), phosphorus, and several ions (K+, Na+, Ca2+, Mg2+) were analysed in shoot material. Compared with control conditions (full irrigation with Hoagland normal) all other treatments inhibited photosynthesis through stomatal closure, accelerated senescence, and decreased biomass. Full irrigation with 12dS m -1 outperformed other stress treatments in terms of biomass production and physiological performance. Biomass correlated positively with N and δ15N, and negatively with Na+ across genotypes and fully irrigated treatments, while relationships across deficit irrigation conditions were weaker or absent. Δ13C did not correlate with biomass across treatments, but it was the best trait correlating with phenotypic differences in biomass within treatments. Tritordeum produced more biomass than durum wheat in all treatments. Its low Δ13C and high K +/Na+ ratio, together with a high potential growth, may underlie this finding. Mechanisms relating δ15N and Δ13C to biomass are discussed. © 2010 The Author.