Grain Yield and Some Physiological Traits Associated with Heat Tolerance in Bread Wheat (Triticum aestivum L.) Genotypes

This research was carried out in the experimental fields of Department of Field Crops, Faculty of Agriculture, the  University of Namik Kemal in 2014-2015. In the study, totally 30 bread wheat (Triticum aestivum L.) genotypes  (15 cultivars; early, medium-early and late-maturing; 10 lines are tolerant to the heat-temperature stress which were  provided by CIMMYT-International Maize and Wheat Improvement Center), 5 lines (were taken from the same  university’s wheat breeding program which was collaborated by the CIMMYT) were used as an experimental material.  The experiment was adjusted in a split-plot design with 3 replicates. Sowing dates (Normal (NS ≈ November 09, 2014)  and Late sowing (LS ≈ January 09, 2015)) were constituted the main plots, and the genotypes constituted the sub-plots.  These physiological traits ((membrane thermostability (MT), canopy temperature (CT), leaf chlorophyll content (LCC)  and stomatal conductance (SC)) were measured at the LS stage due to giving much more correct, logical and meaningful  results, but grain yield (GY) was fixed for all the sowing dates. Obtained findings are: The GY was varied between (4.35- 6.34 t ha-1) for genotypes; the MT was changed between (10.58-66.25%); the CT was realized between (17.67-22.00 oC);  the LCC was varied between (38.30-53.30 SPAD) and the SC was changed between (25.20-166.80 mmol m-2 s-1). It was  observed that most of the CIMMYT originated genotypes are tolerant to high-temperature stress and most of the wheats  that are grown in Thrace Region are negatively affected by the high-temperature stress.