This study determined the thresholds (the onset of decline) for leaf expans
ion (C-L) and transpiration (C-T) responses to soil water deficit in chickp
ea (Cicer arietinum L.) and evaluated their importance to crop performance
under rainfed conditions using a chickpea simulation model in two contrasti
ng locations. Two pot experiments were conducted to determine the threshold
s during adrying cycle, when plant responses were monitored as the soil dri
ed progressively. Leaf area expansion and transpiration did not change unti
l the fraction of transpirable soil water (FTSW) reached 0.48 (C-L) and 0.3
4 (C-T), respectively, and then decreased linearly to FTSW of 0.03 for leaf
expansion and 0 for transpiration. Simulation results of sensivity test sh
owed that for long and intensive terminal droughts, high C-L and C-T and fo
r short and intermittent droughts, low C-L and C-T favor grain yield but th
e yield increases with best combinations of C-L and C-T do not exceed 1% (2
0 kg ha(-1)) and 5% (40 kg ha(-1)), respectively. Thus, the contribution of
C-L and C-T differences in crop performance under water deficit conditions
seems limited. (C) 2000 Elsevier Science B.V. All rights reserved.