Grain yield of bread wheat germplasm under heat and drought stress during the crop season 2023-2024

Forty two advanced bread wheat lines and cultivars Borlaug 100 F2014 and CIANO M2018 were sown on January 15 and 30, 2024, at the Norman E. Borlaug Experimental Station, in the Yaqui Valley, Sonora, Mexico. Plots consisted of 1 bed 2 m long with two rows and 0.80 m apart with two replications, and a seed density of 100 kg ha-1 with two complementary irrigations. Average daily temperature (°C), maximum, minimum, relative humidity, rainfall, heat and cold units were recorded from January 15 to May 15, 2024. The average days for heading of the group was 61 for the first sowing date and 56 for the second one, while days for physiological maturity were 98 and 91, respectively. The average plant height of the group for the first date was 77 cm and 74 for the second one; three lines showed the highest average height with 83 cm. The average thousand grain weight was 46.3 g; the line REEDLING-GL5A_1/5/ 2*SOKOLL/3/PASTOR//HXL7573/2*BAU/4/MEX94.27.1.20/3/SOKOLL//ATTILA/3*BCN showed the highest average TGW with 53.5 g. The average grain yield per plot was 405 g; the line 68.111/RGB-U//WARD/3/AE.SQUARROSA(501) /7/SERI.1B*2/3/KAUZ*2/BOW//KAUZ/4/FRANCOLIN#1/5/MUNAL/6/KACHU#1/KIRITATI//KACHU/8/BORL14 showed the highest average yield with 480 g which corresponded to 6.0 t ha-1, followed by four lines with 470 g (5.88 t ha-1). The average hourly temperature was 18.6 °C with a maximum of 35.8 °C and a minimum of 2.5 °C, the average relative humidity was 61.0 %, there were 8.0 mm of precipitation, and the number of heat and cold units was 231 and 309, respectively.