Black Bean Sensitivity to Water Stress at Various Growth Stages

Producers relying on the traditional central Great Plains cropping system of winter wheat (Triticum aestivum L.)-fallow could increase crop yield and resource sustainability by changing to more diverse crop rotations. Crops suited to the variable timing and amount of precipitation characteristic of this region need to be identified so that rotations can be diversified. This study was conducted to determine the effects of water deficit at various growth stages on leaf area index, plant height, yield components, soil water extraction pattern, and seasonal water use of black bean (Phaseolus vulgaris L.). The study was conducted during the 1995 and 1996 growing seasons near Akron, CO, on a Rago silt loam (fine, montrnorillonitic, mesic Pachic Argiustoll). An automated rainout shelter was used to eliminate precipitation. Irrigation treatments consisted of withholding water at vegetative, reproductive, or grain-filling growth stages. All treatments received 18.3 cm of water during the growing season. Water stress during the vegetative growth stage produced the shortest plants with the least leaf area. Soil water extraction and total water use were also least when water was withheld during the vegetative stage. Seed yield was reduced because of reductions in pods per plant and/or seeds per pod when water stress occurred during the reproductive stage. Black bean appears to have potential as a dryland rotation crop in the central Great Plains when soil water profiles are near field capacity at planting and normal to above normal precipitation is expected.