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LEAF AND NODULE SENESCENCE IN CHICKPEA (CICER ARIETINUM L.) AND THE ROLE OF PLANT GROWTH REGULATORS

SAHAR ALI AND ASGHARI BANO^*

Abstract: The present investigation was aimed to study the effect of Kinetin and Abscisic acid (ABA) on leaf and nodule senescence in chickpea (Cicer arietinum (L.)) cv. CM88, in relation to the changes in the endogenous level of abscisic acid (ABA) and indole-3-acetic acid (IAA). Studies was carried out for study the 1 involvement of hormonal and non-hormonal signal factors involved in nodule senescence, 2 The critical period in the development stages for the initiation of nodule senescence. 3 The correlation of leaf senescence with nodule senescence. The effects of the hormones were studied at four developmental stages; vegetative stage, flowering stage, early pod filling stage and late pod filling stage. The seeds of chickpea (Cicer arietinum (L.) cv. CM88 were soaked for 6h prior to sowing in aqueous solution of Kinetin and Abscisic acid each at 10^-5 M. Both the hormones (at 10^-6 M) were also applied as foliar spray during the vegetative phase of pant (4 weeks after sowing). The plants were allowed to grow under natural conditions. Increase in protein and sugar content of plant leaves was related with the increase in nodule activity at the flowering and early pod filling stages, thereafter, degradation of chlorophyll and protein content became more pronounced in old leaves as compared to young leaves. Kinetin at 10^-5M was more effective than kinetin at 10^-6M to delay leaf and nodule senescence. ABA (10^-5M) was effective in enhancing leaf and nodule senescence resulting in significant decrease in plant growth and yield as compared to the control. The effect of ABA in enhancement of leaf and nodule senescence is mediated possibly via the increased proline content of leaves and decrease in IAA and kinetin level. The exogenous application of kinetin decreased the endogenous level of ABA in the treated plants but elevated the IAA content of the root significantly at the early pod filling stage. Nodule senescence coincided with leaf senescence and appears to be correlated with the degradation of chlorophyll and protein content as well as the sugar assimilation in the host plant which in turn delay the degeneration of pink bacteroids tissue of nodules and the nitrogenase activity.

Department of Plant Sciences, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan.