GENETIC ADVANCEMENT IN BREAD WHEAT VARIETIES RELEASED FOR THE BAJÍO REGION (MEXICO) UNDER NORMAL AND RESTRICTED IRRIGATION

Wheat (Triticum aestivum L.) provides approximately 20 % of the proteins and calories consumed globally. Genetic advancement in yield is crucial to satisfy the demand of the growing world population. The aim of this study was to estimate genetic progress in agronomic traits of varieties released in El Bajío (Mexico) between 1975 and 2016 under normal and restricted irrigation. The hypothesis was: with the breeding of wheat varieties for over 40 years for the region of El Bajío, advances have been made in grain yield. The genotypes planted were Salamanca S75, Cortazar S94, Bárcenas S2002, Urbina S2007, Alondra F2014 and Cisne F2016 during the 2016-17 and 2020-21 agricultural cycles in three irrigation schedules, two at 0 and 55 days after planting, three at 0-45 and 75 and four at 0-45-75 and 100 days after planting. Phenology, yield and its components were measured, and the treatment design followed a randomized complete block design with arrangements in subdivided plots and three replications. Using the weighted phenotypic model and its graphical representation through the SREG biplot, it was determined that recently released varieties outperformed the grain yield of older varieties in all three irrigation schedules. The varieties released between 1975 and 2016 displayed no changes in days to heading and maturity, since only early genotypes were advanced in the selection process. For grain yield, a genetic progress was obtained of 26.3, 41.6 and 37.6 kg ha-1 year-1 for the two, three and four irrigation schedules, respectively, which was related to an increase (p ≤ 0.01) in aerial biomass and a higher number of spikes and grains per unit area.