Seed growth of desi and kabuli chickpea (Cicer arietinum L.) in a short-season Mediterranean-type environment

The influence of terminal drought on the seed growth of 3 chickpea (Cicer arietinum L.) genotypes was examined in a field experiment at Merredin, Western Australia. Tyson, a small-seeded desi cultivar, ICCV88201, a desi breeding line (sister line to the recently released Sona cultivar) with medium-sized seed, and Kaniva, a kabuli cultivar with large seed, were grown under rainfed and irrigated conditions. In the rainfed plots, leaf water potential had decreased from above -1.2 MPa to about -2.5 MPa and net photosynthesis from 21 to 29 mu mol CO(2)/m(2).s to below 10 mu mol CO(2)/m(2).s, by the time seed filling commenced. Rainfed plants had significantly fewer pods than irrigated plants, regardless of genotype. In rainfed plants average seed weight was reduced by 19, 23 and 34% and yield by 74, 52 and 72% in Tyson, ICCV88201, and Kaniva respectively. Individual pods were tagged at pod set on previously-selected representative plants and were weighed separately from the rest of the plant over 6 subsequent harvests so that the rate and duration of seed fill could be measured. Genotypic differences in the maximum rate of seed fill were found to exist in chickpea. In both irrigated and rainfed conditions, Kaniva had the highest maximum rate of seed fill followed by ICCV88201 and Tyson. Both the rate and duration of seed growth were reduced in the rainfed plants, regardless of genotype. Reductions in the dry weight of the pod shell suggest that the remobilisation of dry matter from the pod may contribute 9-15% of the seed weight in rainfed chickpea.