The expansion of wheat crops to areas with higher temperatures, like the Central-Brazil, is one of the main actions to decrease the wheat importation. For this reason, heat tolerant genotypes are essentials. The objective of this study was to identify genetic variability for heat tolerance, to identify heat tolerant wheat populations and genitors, and to quantify the high temperature effects on those wheat genotypes. Two experiments were carried out in Viçosa, Minas Gerais State. A 16x16 square lattice design was used with two replications, where 240 families from eight segregating populations (30 families from each population) plus 16 genitors were evaluated. In the first experiment sowed in February 2007 (summer), F2:4 families were evaluated. In the second one sowed in June 2007 (winter), F2:5 families were evaluated. The flowering, plant height, grain yield, and thousand grain weight were evaluated. Different temperature conditions from emergence to flowering were crucial on genotype responses when compared the two environments. There was found genetic variability for heat tolerance between wheat genitors and segregating populations. All the evaluated traits presented reduction under high temperatures, being the grain yield the most affected, followed by plant height, flowering, and thousand grain weight. The genitors BR 24, Aliança, and EP 93541 and the populations BH1146/BR24//Aliança/EP93541, BR24/Aliança//EP93541/CPAC9662 and Aliança/EP93541//CPAC9662/Pioneiro were the most heat resistant.
Triticum aestivum L; high temperatures; wheat breeding
