LEAF AND NODULE SENESCENCE AND THE ROLE OF GROWTH REGULATORS IN CHICKPEA

Abstract

The present investigatIon was alrl1cd at deletlt'lillulg lhe eReCI of kinetin and Abscisic acid (AIlA) 011 leaf und nod ule senescence JO chickpea (Cin!r ammlllllll (L» cV CM88. Tht! changes in the endogenolls level of ABA and indole-3-acetic acid ( IAA) have also been determined The seeds were soaked in aqueous solution of ki net in and J\bscisic acid each al 1 0'~M ror 6h prior to sowing. Bolh the ho rmones were also applied du rillg the vegetat ive phase between 1000 h- 1200 h as foliar spray at 1O.('M. The plants were allowed to grow under natural conditions and the experiments were repenled for three consecutive years. The effects of the hormones were studied (,.111 young expanded leaves and rlilly expanded mature leaves at four developll1cll lHI stages. vegetative stage. flowering stage, early pod filling stage and lale pod tilling stage Increase in protein content in plant leaves coincided with tile intl'ease in nodlll~ activity at both the nowering and early pod IWing stages, after which senescence of the leaves became more evident. Degradation of chlorophyll and protein contcnt becomc more pronounced in old leaves as compared to young leaves Killctin fi t 1O'~ M was more clTcc tivc treatment than kin etin at IO·6M in delaying leur und nodule senescence by its stimulatory cObc! on chlorophyll. protein and sugar C()llleni or young leaves and hy increasing diameter of pink bacteroid tissue, nodule weigh I ilnd nitrogenase act ivi ty per mill pink bacteroid tissue oC the noodles at both the Ilowcring and early pod lilling stages. Both of the concentrations of ABA ( IO.JM uml IO'!>M) were cn'cclive in enhancing leaf and nodule senescence by degradation of chlorophyll. P'-Oleil1 and sligar content of young leaves, and by decreasing diameter of pink bacleroid lis~ue, nodule v.eight and nit rogenase act ivity or ihe nodules at both the !luwering aml eadv pod fi lling stages. BOlh Ihe treatments of ADA caused earl>' malUnly resul ting in signilicalll decrease in pi am growth and yield as compared to Iht.: control fhe endogellous lcvd uf ABA was higher til late pod fil lLng stage than that of t he vegetative stage. whereas e xogen() lI ~ applica tion of kinetin decreased tile endogenolls level of' AIlA in the treated plant s. The IAA co ntent orllle 1'001. increa sed sig ninc8nt ly to llowing kinctin treatmcnts at the ea rly pod filling stage. The effect or ARA ill enhancement or leaf and nodule senescence is possibly mediated by the increased proline content of leaves as well as the antagonistic eOe cl or ABA on the content of growth promoting hormones as IAA and kinetin. Nodule senescence nppcarcd to be associated with leaf senescence and the fonner is appears to be correlated with the diameter of pink bacteroides tissue