Association of Some Photosynthetic Characteristics with Canopy Temperature in Three Cereal Species under Soil Water Deficit Condition.

Canopy temperature (CT) is used as a selection tool to improve crop adaptation to drought. The aim of this work was to investigate association of some photosynthetic characters with CT during grain filling in three cereal species. For this objective, a twoyear study (2009-2011) was carried out in Kurdistan Province in western Iran. Four genotypes of triticale, three cultivars of bread wheat, and a new variety of barley were compared under well watered (WW, Ψsoil water= -3 bar) and deficit water (DW, Ψsoil water= - 12 bar) conditions in a randomized complete block design (RCBD) with a split-plot arrangement. Compared with well-watered plants, water stressed plants displayed 1.44°C higher canopy temperature irrespective of plant species. Under water stress condition, the high yielding genotypes had lower canopy temperature than low yielding ones by 1.23°C. Results showed that under water deficit condition triticale relative to commercial cultivar of wheat and barley had a higher adaptability to drought as indicated by its higher yield (59.5 g m-2 more than average) and lower CT (0.28°C lower than average). The main physiological traits correlated with canopy temperature under DW treatment were stomatal conductance (gs) (r= -0.73*), photosynthetic rate (Pn) (r= -0.76*), the maximal quantum yield of primary photochemistry (Fv/Fm) (r= - 0.71*), chlorophyll content at grain filling (r= -0.72*) and leaf temperature (LT) (r= 0.82**). Thus, canopy temperature seems to play an important role in the physiological basis of grain yield in different cereal species, and can be used as a selection tool in breeding programs under water deficit condition in Iran. [ABSTRACT FROM AUTHOR]