Screening and agronomic benefits of the stay-green trait in common bean genotypes
Selecting a trait linked to metabolic pathways that enhance resistance and tolerance to biotic and abiotic stresses may be an excellent alternative. A practical approach to increase the productivity of annual crops is to maximize the photosynthetic efficiency in plant breeding. The purpose of this study was to discriminate common bean genotypes during physiological senescence with regard to the stay-green trait and analyze its effects on other traits of agronomic interest. Ten common bean genotypes were analyzed in a randomized complete block design with three replications. The stay-green trait was assessed by visual scores at harvest. The chlorophyll a content, chlorophyll b and green pod color were also evaluated during senescence (75, 80, 85, 90, and 95 days after sowing). Pod maturation of all evaluated genotypes was standard when they reached 95 days after sowing. The stay - green feature was detected only in the genotypes BRS Expedito, FT - Tarumã and BAF071. Genetic variability in the mechanisms related to late senescence is indicated by: i) a high initial chlorophyll a content; and ii) reduced chlorophyll degradation throughout senescence. Plants with stay-green properties were significantly correlated with a lower incidence and severity of plant pathology, greater stem diameter, and higher grain yield.