EFFECT OF POLYETHYLENE GLYCOL-INDUCED WATER-STRESS ON GERMINATION AND RESERVE CARBOHYDRATE-METABOLISM IN CHICKPEA CULTIVARS DIFFERING IN TOLERANCE TO WATER-DEFICIT

Chickpea (Cicer arietinum) cvs C-214 and GL-769 are relatively tolerant to water deficit than cvs PBG-1 and G-130. The seeds of cvs C-214 and PGB-1 were germinated in dark for six days under reduced water potential induced by polyethylene glycol. Under these conditions, the observed decrease in seed germination and in length and biomass of epicotyls and hypocotyls was more in PBG-1 as compared to C-214. Water stress caused an increase in total soluble sugars and bound fructose in cotyledons, hypocotyls and epicotyls of both the chickpea cultivars irrespective of their sensitivity to water stress. The alpha-amylase (EC 3.2.1.1) activity in cotyledons of stressed and normal seedlings of PBG-I was significantly less as compared to its activity in C-214. A decrease in starch content of embryonic axis (hypocotyl and epicotyl) and an increase in cotyledons under water stress in C-214 and PBG-1 cultivars was related to the activity of a-amylase in these tissues. The depletion of raffinose series oligosaccharides was delayed in the cotyledons of stressed seedlings of both the cultivars. This observation along with decrease in the alpha-amylase activity and slow depletion of starch in cotyledons suggested a decreased formation of sucrose in cotyledons of stressed seedlings. As compared to chickpea cvs PBG-1 and G-130, in chickpea cvs C-214- and GL-769, the specific activity of alpha-amylase and total amylase was high in cotyledons of dry seeds and seeds germinating in absence of water stress.