The impact of tillage on pinto bean cultivar response to drought induced by deficit irrigation

Drought stress is a major factor limiting yield of dry bean (Phaseolus vulgaris) and drought tolerant cultivars are being developed. Reducing tillage in row crops has advantages of conserving moisture and increasing water infiltration, and may alter the response of dry bean cultivars to drought stress. The goal of this study was to evaluate the response of eight pinto bean cultivars to deficit irrigation when grown under conventional (CT) vs strip tillage (ST). Drought was imposed to one half of the plots approximately 30 days after emergence by reducing irrigation by 48% [deficit irrigation (DI)] compared to full replacement of estimated evapotranspiration (FI = full irrigation). DI reduced bean seed yields 48 and 46% in 2015 and 2016, respectively. Dry bean cultivars varied in their response to drought stress by year. ST improved bean stands both years and moderated the decline in soil water, particularly in the upper 0-15 cm of the soil profile under DI when compared to CT. Mid-season shoot length, top biomass, leaf area index, and canopy cover were generally greater, and light transmittance through the plant canopy lower in ST compared to CT. ST increased bean seed yield 9% in one of two years over CT. ST improvements in crop stand, shoot and canopy development, and seed yield were consistent across irrigation levels and cultivars. Pinto bean growth and yield responses to ST were generally either favorable or neutral when compared to CT suggesting that implementing ST could benefit dry bean performance under both favorable and limited water conditions.