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 str ess on physiological parameters, growth and yield by correlating several ph ysilological and growth parameters for bean plaIlts under drought condition s. 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 a t Durnast, Bavaria, Germany. Water relation measurements (leaf water potent ial and stomatal conductance), photosynthetic rate, plant growth and yield measurements were recorded. Water stress lower than -40 hPa resulted in a d ecline of leaf water potential and stomatal conductance. Water stress also reduced all growth and yield parameters. This effect was significant, espec ially 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 rel ationship between yield and water stress levels. The correlations between l eaf water potential and the other physiological and growth parameters are d iscussed.