Growth and sucrose synthase activity of developing chickpea (Cicer arietinum L.) seeds under field conditions

Seed growth characteristics and sucrose synthase activity in chickpea (Cicer arietinum L.) were examined in a field experiment at Merredin, Western Australia. ‘Sona’, a small-seeded desi cultivar, and ‘Kaniva’, a large-seeded kabuli cultivar, were grown after flowering with irrigation and under a rainout shelter, used to induce terminal drought. Seed and pod wall dry weight followed a similar pattern in the two cultivars with terminal drought significantly reducing the dry weight of the pod wall and seed in both cultivars. The pod wall reached its maximum dry weight 21 days after podding (DAP) in ‘Kaniva’ and 28 and 35 DAP in ‘Sona’ with terminal drought and irrigation, respectively. The dry weight of the pod wall decreased during seed filling, particularly in the plants subjected to terminal drought. The increase in seed dry weight followed a sigmoid curve with a lag phase of 14 DAP and 21 DAP in ‘Kaniva’ and ‘Sona’, respectively, followed by a rapid almost-linear phase until 35 DAP when the dry weight leveled off and even decreased slightly near maturity. Sucrose synthase activity peaked at 32 DAP in ‘Kaniva’ and 35 DAP in ‘Sona’ and then decreased to near zero at maturity. A significant and positive association was observed between seed dry weight at maturity and peak sucrose synthase activity in both cultivars and both treatments. We suggest that sucrose synthase is a good physiological indicator for use in breeding for improved seed size in chickpea.