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

Seed growth characteristics and sucrose synthase activity in chickpea (Cicer arietinum L.) were examined in afield experiment at Merredin, Western Australia. ‘Sona’, a small-seeded desi cultivar, and ‘Kaniva’, alarge-seeded kabuli cultivar, were grown after flowering with irrigation and under a rainout shelter, used to induceterminal drought. Seed and pod wall dry weight followed a similar pattern in the two cultivars with terminaldrought significantly reducing the dry weight of the pod wall and seed in both cultivars. The pod wall reached itsmaximum dry weight 21 days after podding (DAP) in ‘Kaniva’ and 28 and 35 DAP in ‘Sona’ with terminaldrought and irrigation, respectively. The dry weight of the pod wall decreased during seed filling, particularly inthe plants subjected to terminal drought. The increase in seed dry weight followed a sigmoid curve with a lagphase of 14 DAP and 21 DAP in ‘Kaniva’ and ‘Sona’, respectively, followed by a rapid almost-linear phase until35 DAP when the dry weight leveled off and even decreased slightly near maturity. Sucrose synthase activitypeaked at 32 DAP in ‘Kaniva’ and 35 DAP in ‘Sona’ and then decreased to near zero at maturity. A significant andpositive association was observed between seed dry weight at maturity and peak sucrose synthase activity in bothcultivars and both treatments. We suggest that sucrose synthase is a good physiological indicator for use inbreeding for improved seed size in chickpea.