Efecto del riego suplementario en la producción de biomasa y grano de frijol de temporal en Zacatecas, México

in the semiarid highlands of north-central mexico, the lack of water for agricultural production is an important problem, particularly since annually a depletion of two m in the water mirror of local wells is taking place and the water storage capacity in dams is limited. because of the above situation, the optimization of water resources through supplemental irrigation in critical stages of bean sown under rainfed conditions is important. the aim of the present research was to determine the effect of supplemental irrigation on shoot biomass accumulation and seed yield in two sets of improved cultivars with different seed type. two experiments were established at cezac experiment station in zacatecas, mexico in 2001; nine black-seeded cultivars were evaluated in one trial, and 14 seed colored cultivars in a second one. all cultivars are of the type iii indeterminate growth habit. two soil moisture levels were utilized: 1) rainfall plus supplemental irrigation and 2) natural rainfall conditions. the rainfall plus supplemental irrigation treatment consisted of maintaining the available soil moisture above 50% throughout the crop-growing season, which was achieved by rainfall plus two irrigations, one at pre- and the second at the flowering stages. the natural rainfall treatment depended only on the rainfall occurred during the growing season. in both experiments, average shoot biomass accumulation and seed yield of the rainfall plus supplemental irrigation were significantly higher (p<0.01) than those in the rainfall treatment. in general, black seeded cultivars, that were significantly later to mature (p<0.05), showed higher shoot dry weight and seed yield in response to the treatment rainfed+supplemental irrigation than the colored cultivars. there was a differential response of the cultivars to the moisture treatments; outstanding black seeded cultivars were negro zacatecas, negro ontiveros and negro z524 from the mesoamerican race, while among seed colored cultiva