SEED YIELD AND HARVEST INDEX OF PINTO AND FLOR DE MAYO DRY BEANS GERMPLASM UNDER STRESS BY HIGH TEMPERATURE

Abstract

The productivity of irrigated dry beans planted in February at the Bajío region of Guanajuato, Mexico is limited by high temperatures during the reproductive stage. The aim of this study was to determine the effect of high temperature on seed yield and harvest index of improved bean germplasm of the Pinto and Flor de Mayo types and to identify high-yielding materials under irrigation. For that, in 2018 16 Pinto and 15 Flor de Mayo bean genotypes were evaluated. During the growth cycle a pre-sowing and three supplementary irrigations were applied. Each material was planted in two 30-m rows and at harvest the plants of six 1-m sections were randomly taken to determine the number of pods, number of grains, biomass production, grain yield, the weight of 100 seeds, and the harvest index (HI). Data from each set of genotypes were analyzed separately under a completely randomized design and withingroups test of means (Tukey, P ≤ 0.05). During the reproductive stage, maximum day and night temperatures exceeded 30 and 20 ^oC, respectively. In both sets there were significant differences (P ≤ 0.05) in the evaluated traits. The highest yielder in the Pinto type group was the cv. Salinas (3.79 t ha^-1), and in the Flor de Mayo type the line (PS / FM Dolores)-M-9-2-9 (3.27 t ha^-1), both showed a high number of pods per m² and grains per pod. In general, in both groups the HI was low. In the Pinto-type materials, the correlation between HI with seed yield was positive (r = 0.75**), while in the Flor de Mayo group the correlation of HI with biomass was negative (r = -0.74**), which showed the importance of mobilization capacity of photoassimilates towards the seeds under heat stress conditions and the superiority of the Pinto genotypes.