TOWARDS THE RELIABLE PREDICTION OF TIME TO FLOWERING IN 6 ANNUAL CROPS .5. CHICKPEA (CICER-ARIETINUM)

Four genotypes of 'desi' and two of 'kabuli' chickpea (Cicer arietinum ) were sown at six locations in Australia on various dates between 198 6 and 1988, giving 22 combinations of site and sowing date with divers e photothermal environments. Times from sowing to first flowering (f) varied from 30 to 162 d, mean pre-flowering temperatures from 10.8-deg rees to 29.3-degrees-C and mean photoperiods from 11.3 to 15.6 h d-1. There was no evidence that any observation had been obtained in photop eriods shorter than the ceiling photoperiod (P(ce)) or longer than the critical photoperiod (P(c)). This suggests that, in typical agricultu ral environments, chickpea crops experience photoperiods (P) which sho uld satisfy the condition P(ce) < P < P(c). In one 'kabuli' and two 'd esi' genotypes, 1/f was influenced by both temperature and photoperiod . The coefficient of determination (R2) for a linear, additive rate of development model ranged from 0.74 to 0.80, with no significant diffe rence in either temperature sensitivity or photoperiod sensitivity amo ng these three genotypes. In the remaining three genotypes, no signifi cant response to temperature was detected between 10.8-degrees and 29. 2-degrees-C, so rate of progress to flowering was influenced solely by photoperiod. There was no significant difference in the sensitivity o f 1/f to P among these three genotypes. The linear, additive rate mode l found here to be so satisfactory as a predictive tool for phenology, is also shown to have much wider general application.