Effect of water stress and plant density on canopy temperature, yield components and protein concentration of red bean (Phaseolus vulgaris L. cv. Akhtar)

In order to study the effects of different irrigation regimes and plant density on yield
component and protein concentration and crop water stress index (CWSI), under research field
conditions a split plot arrangement was conducted in completely randomized block design
during two years. The first factor of variables was the effects of 4 irrigation levels 120% (I1),
100% (I2), 80% (I3) and 60% (I4) of Standard evapotranspiration and the second factor was the
spacing of 5 cm (D1), 10 cm (D2) and 15 cm (D3) between plants within a row. Results indicate
that the number of pods in each plant and the grains in each pod decreased when density
increased, but the hundred-grains-weight and the height of bean plants increased. When
irrigation increased, various increases were observed in the yield, the number of pods in each
plant, the grains in each pod, the hundred-grains-weight and the height of bean plants, but the
grain protein decreased. Protein concentration increased with more severe water deficit in the
soil. The protein concentration directly correlated with total irrigation water during the growing
season (TI) and the exponential equation P=33* e -4E-04TI can be used for protein concentration
prediction. The effect of the irrigation water was significant and CWSI increased with increased
soil water deficit. The effect of the density for CWSI was not significant. Grain yield (GY)
directly correlated with CWSI and the exponential equation, GY=696.2(CWSI)-0.51 can be used
for the prediction of grain yield. The CWSI value is useful for evaluating crop water stress in
beans and thus it could be useful in timing the irrigation. Results of this research indicate that
yield components such as height of bean plant, the number of pods in each plant and the number
of grains in each pod were significantly different by applying the different irrigation strategies at
the three different lengths of plant spacing within a row.