Water stress-induced injury to reproductive phase in chickpea: Evaluation of stress sensitivity in wild and cultivated species in relation to abscisic acid and polyamines

Chickpea (Cicer arietinum L.) is more sensitive to water stress during its reproductive growth and consequently experiences substantial yield loss. Wild species being relatively tolerant to abiotic stresses offer a potential gene source for incorporation of drought tolerance in cultivated species. In the present study, the differential stress sensitivity of wild (Cicer reticulalum Ladiz.) and cultivated species (C. arietinum) was evaluated by subjecting the plants of both the species to water stress for 14 days during the reproductive phase and examined for stress injury, endogenous status of polyamines (PA) and abscisic acid (ABA). Comparatively, the cultivated species experienced higher stress injury (assessed as electrolyte leakage, 2,3,5-triphenyl tetrazolium chloride reduction ability, chlorophyll loss) as well as decreased leaf water potential (Psi(w) -2.48 MPa) than the wild species (-1.98 MPa). The stressed plants of cultivated species lost more number of flowers (62 %) and pods (65 %) when compared with the unstressed ones while those of wild species showed 30 % and 44 % loss, respectively. The number of infertile pods was significantly more in stressed plants of cultivated species than in those of wild species. The endogenous status of PA revealed that putrescine (PUT), spermidine (SPD) and spermine (SPM) levels accumulated to a higher extent in the cultivated species relative to the wild species until the eighth day of stress, and thereafter, the wild species had significantly higher levels of PA. In contrast, ABA levels increased to a higher extent in the wild species until the eighth day of stress and declined subsequently to a greater degree than the cultivated species. The injury to reproductive growth appeared to accentuate with reduction in leaf Psi(w) that was coupled with depletion of PA in both the species, especially in the cultivated one. Exogenous application of 10 mm PUT partially alleviated the damage to reprodtictive growth by increasing the leaf water status and chlorophyll content while decreasing the ABA content, which resulted in improvement of retention of flowers and pods, particularly in the cultivated species.