Effect of long-term drought stress on growth and yield of bean plants (Phaseolus vulgaris L.)

The aim of this work was to study the effect of long-term drought stress on bean growth and yield and to estimate the quantitative effect of water stress on physiological parameters, growth and yield by correlating several physilological and growth parameters for bean plaIlts under drought conditions. Bean plants were grown under difierent levels of water stress (-40, -100, -150, and -200 hPa). The experiments were conducted in a well controlled greenhouse at the research station of the Institute for Vegetable Science at Durnast, Bavaria, Germany. Water relation measurements (leaf water potential and stomatal conductance), photosynthetic rate, plant growth and yield measurements were recorded. Water stress lower than -40 hPa resulted in a decline of leaf water potential and stomatal conductance. Water stress also reduced all growth and yield parameters. This effect was significant, especially at -150 and -200 hPa. Plants at -40 hPa grew normally while plants at -100 hPa showed some drought acclimation. Plants at -150 and -200 hPa were extremely affected by water stress. The results indicate a high linear relationship between yield and water stress levels. The correlations between leaf water potential and the other physiological and growth parameters are discussed.