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

Abstract

Canopy temperature (CT) is used as a selection tool to improve crop adaptation to drought. The aim of this work was to investigate as sociation of some photosynthetic characters with CT during grain filling in three cereal species. For this objective, a two- year study (2009-2011) was carried out in Kurdistan Province in western Iran. Four genotypes of triticale, three cultivars of bread wh eat, and a new variety of barley were compared under well watered (WW, Ψ soil water = -3 bar) and deficit water (DW , Ψ soil water = - 12 bar) conditions in a randomized complete block d esign (RCBD) with a split-plot arrangement. Compared with well-watered plants, wat er stressed plants displayed 1.44°C higher canopy temperature irrespective of plant spe cies. Under water stress condition, the high yielding genotypes had lower canopy temperatur e than low yielding ones by 1.23°C. Results showed that under water deficit condition t riticale relative to commercial cultivar of wheat and barley had a higher adaptability to dr ought 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 tempera ture under DW treatment were stomatal conductance (g s ) (r= -0.73*), photosynthetic rate (P n ) (r= -0.76*), the maximal quantum yield of primary photochemistry (F v /F m ) (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 physiologica l basis of grain yield in different cereal species, and can be used as a selection tool in bre eding programs under water deficit condition in Iran. Keywords: Barley, Chlorophyll fluorescence, Drought stress, Net photosynthetic rate, Triticale.