The evapotranspiration rate of unstressed 'Maruguar' clusterbean (Cyamposis
tetragonoloba (L.) Taubert) in an arid region at Jodhpur was 2.4-3.9 mm/da
y during early growth, 6.3-9.3 mm/day at peak vegetative stage, 5.3-5.8 mm/
day at flowering/pod formation stage and 1.2-4.2 mm/day at maturity stage.
The crop coefficient (ratio of actual to potential evapotranspiration) was
0.42-0.58 at early growth stage, 0.62-1.17 at peak vegetative stage, 0.70-1
.05 flowering and pod formation stages and declined to 0.43-0.60 at maturit
y. Irrigation enhanced seed yield of clusterbean by 123% at 50% rate and 18
0% at 100% rate of water application from that of rainfed crop. Ther water-
use efficiency of the crop varied from 1.47 to 4.10 kg/ha/mm and the radiat
ion-use efficiency for unit dry matter production of intercepted photosynth
etically active radiation was 0.57-1.21 g/MJ under rainfed to 1.42-2.31 g/M
J under irrigated condition. Advection enhanced evapotranspiration of clust
erbean by 50-78%.