YIELD AND DROUGHT STRESS TOLERANCE OF BLACK BEAN GENOTYPES IN THE STATE OF VERACRUZ

Abstract

During the 2007 Winter-Spring growing season, a group of bean genotypes from the Mesoamerican race was evaluated under irrigated and drought stress conditions, in order to identify those having high yield efficiency under both moisture conditions. Two experiments were established in Medellín de Bravo, Ver., México, one conducted under irrigation during the whole cycle, and the other by with drawing irrigation at the beginning of the flowering stage. Thirteen lines and three varieties, ‘Negro Tacaná’, ‘Negro INIFAP’ and ‘Negro Jamapa’, were evaluated in a randomized complete block design with three replications. The number of days to maturity, number of seeds per pod, weight of 100 seeds and seed yield were quantified. As efficiency indexes we used the drought susceptibility index (DSI), the geometric mean (GM) and the relative efficiency index (REI). The yield reduction caused by the stress treatment was 68.8%. With DSI values < 0.86 genotypes ELS-15-55, NGO 17-99 and ‘Negro INIFAP’ were the most drought tolerant, whereas NGO 99038, NGO 99054 and NGO 99176 were the most susceptible. NGO 17-99 and ‘Negro INIFAP’ showed the highest values of GM, while DOR-667 the highest REI. With these indexes, high yielding genotypes under both moisture conditions were selected, and with the DSI values we selected the genotypes with minor yield reduction due to drougth stress. Under irrigation (r = 0.83**) as well as under drought stress (r = 0.88**), seed weight was positively correlated with seed yield, and under stress the number of seeds per pod (r = 0.78**) was also correlated to seed yield.