Influence of water deficits on the water relations, canopy gas exchange, and yield of chickpea (Cicer arietinum)

Chickpeas (Cicer arietinum L., cv H-355) were subjected to four irrigation treatments after crop establishment: (i) unirrigated (D); (ii) irrigated until flower initiation [85 days from sowing (DAS)] and unirrigated thereafter (WD); (iii) unirrigated until active seed setting (129 DAS) and irrigated thereafter (DW); (iv) irrigated throughout (W). Several plant processes were measured on clear days betweem 85 and 144 DAS. The unirrigated plants had lower leaf water potentials, canopy evapotranspiration rates (ET), canopy photosynthetic rates (PN), plant dry weight and grain yield compared to the irrigated plants, but increased canopy-air temperature differences (T_c-T_a). Cessation of irrigation at flowering induced a rapid decrease in canopy photosynthesis and reduced the grain yield by 33% due to a decrease in the number of pods set. Irrigation from 129 DAS resulted in some recovery of grain yield resulting from the development of a small number of late pods with small seeds. Among yield components, water stress primarily affected the number of pods per plant and had little effect on the grain number per pod. Grain yield was linearly related to pod number, leaf water potential, and mean PN.