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Peer-review: Yes - Open Access: Yes|http://science.thomsonreuters.com/cgi-bin/jrnlst/jlresults.cgi?PC=MASTER&ISSN=0022-0957

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 17 dS m21), 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 D13C, d15N, 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 12 dS m21 outperformed other stress treatments in terms of biomass production and physiological performance. Biomass correlated positively with N and d15N, and negatively with Na+ across genotypes and fully irrigated treatments, while relationships across deficit irrigation conditions were weaker or absent. D13C 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 D13C and high K+/Na+ ratio, together with a high potential growth, may underlie this finding. Mechanisms relating d15N and D13C to biomass are discussed.

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Oxford

CIMMYT Staff Publications Collection