The photothermal response of three Kabuli chickpea (Cicer arietinum L.) cultivars, at different growth stages, to eight irrigation treatments in 1998/99 and four irrigation treatments in 1999/2000 was studied on a Wakanui silt loam soil in Canterbury, New Zealand (43°38S, 172°30E). The rate of development from emergence to flowering (e-f) and sowing to harvest maturity were strongly and positively associated (R2=0·87, P<0·001) with mean temperature during those periods. All phenological stages considered (sowing to emergence, e-f, flowering to podding, podding to physiological maturity and physiological maturity to harvest maturity) depended upon accumulated thermal time (Tt) above a base temperature (Tb) of 1 °C.
An accurate prediction of time of flowering was made based on an accumulated mean Tt requirement of 629 °Cdays from e-f (R2=0·91, P<0·001). Fully irrigated crops had higher maximum dry matter accumulation (maxDM; 1093 g/m2), duration of exponential growth (DUR; 99 days), weighted mean absolute growth rate (WMAGR; 12·2 g/m2 per day) and maximum crop growth rate (MGR; 17·1 g/m2 per day). In 1998/99 the positive response of maxDM and MGR depended on a significant (P<0·01) interaction between irrigation and sowing date. The maxDM during the season was highly correlated with DUR and MGR (R2=0·79 and 0·65). It is concluded that to maximize chickpea biological yield in the dry season of the cool-temperate subhumid climate of Canterbury, irrigation should extend across all phenological stages.
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