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The aim of this study was to determine the optimum water use of the dry bean (Phaseolus vulgaris L.). Such information is needed by planners and producers for the design of irrigation schemes to minimise yield reductions under water deficit conditions. Under the present experimental conditions, high grain yields were obtained by meeting the full water needs of the crop (1.94-2.43 Mg ha-1), by meeting 75% of their needs (1.92-2.40 Mg ha-1), or by irrigation throughout the growing season except during ripening (1.93-2.23 Mg ha-1). Grain yields were reduced when irrigation water was not provided during the flowering and yield formation periods, and did not increase significantly in such cases even if water had been supplied during the establishment, vegetative, and ripening periods. The yield response factors for the entire growing season, and for the vegetative, flowering, yield formation and ripening periods, were 1.28, 0.36, 0.84, 0.80, and 0.08 respectively. Thus, to achieve effective vegetative production in semiarid regions such as Isparta, irrigation is absolutely necessary. Under limited water conditions, a water deficit of 25-50% is tolerable throughout the growing season, or during the vegetative and ripening periods. El objetivo de este trabajo fue optimizar el uso de agua para la judía de grano (Phaseolus vulgaris L.), lo que es necesariopara que productores y gestores puedan diseñar esquemas de riego en condiciones deficitarias de agua. En las condiciones experimentales de este trabajo se obtuvo una alta productividad (1,94-2,43 Mg ha-1) cuando las necesidades de agua estaban completamente cubiertas. Cuando las necesidades de agua estaban cubiertas en un 75% y cuando se regaba toda la campaña excepto en la época de maduración, la productividad fue 1,92-2,40 y 1.93-2.23 Mg ha-1, respectivamente. El rendimiento de grano se redujo cuando no se suministró agua de riego durante los periodos de floración y maduración de granos, y este rendimiento no aumentó significativamente en tales casos aunque el agua se suministrara durante los periodos de establecimiento, vegetativo y maduración. Los factores de respuesta del rendimiento para el periodo de crecimientocompleto, y para los periodos vegetativo, de floración, de formación de granos y de maduración fueron de 1,28,0,36, 0,84, 0,80 y 0,08 respectivamente. Por tanto, para conseguir una producción efectiva en regiones semiáridas como Isparta, el riego es absolutamente necesario. En condiciones restringidas de agua, un déficit del 25-50% es tolerable a lo largo de toda la campaña, o durante los periodos vegetativo y de maduración.

In a greenhouse pot experiment conducted in Turkey during 2001, onion seedlings were transplanted on May 31 at the density of five plants per pot. On this date the soil water content of all pots were at field capacity. The pots were weighed daily until harvest (December 2), and the data were used to determine the daily evapotranspiration and quantity of irrigation. Eight irrigation treatments were applied, designated as I-1 full irrigation (non-deficit treatment), and I-2, I-3 and I-4 no irrigation in the vegetative growth periods, yield formation and ripening, respectively, and I-5, I-6, I-7 and I-8 received 0.0, 0.25, 0.50 and 0.75 times the soil water depletion in the treatment I-1 on the same day. For each treatment, the following parameters were analysed and compared: applied irrigation depth, daily and seasonal evapotranspiration, bulb yield, yield response factor (k(y)), irrigation water use efficiency (IWUE) and water use efficiency (WUE). The findings indicated that onion plants were very sensitive to lack of soil water during the total growing season and the yield formation period, but rather insensitive in the vegetative and ripening periods. High water use and water use efficiencies were observed with increasing levels of irrigation, or no irrigation in the vegetative period. (C) 2004 Elsevier B.V. All rights reserved.