REGULATION OF CORRELATIVE SENESCENCE IN ARACHIS-HYPOGAEA L BY SOURCE-SINK ALTERATION THROUGH PHYSICAL AND HORMONAL MEANS

Amongst the plants (Arachis hypogaea) subjected to differential reprod uctive manipulations, the leaf levels of chlorophyll and sugar and the dry weight of the aerial plants increased more (except sugar level in defruited plant) in the deflorated plants than either in the defruite d or control plants, and the order of senescence was: control > defrui ted > deflorated, Seed yield per plant increased in deflorated plants as a result, of increase in the number of pods (sink size) and reducti on in the sink strength (seed wt per pod). While 75 % defoliation caus ed a decrease in all the parameters relating to senescence (chlorophyl l, protein, reduced nitrogen, sugar and dry wt), 25 % defoliation caus ed a slight decrease of chlorophyll level of leaf and aerial plant wei ght. However, the level of protein and reduced nitrogen in the leaf an d sugar in the stem increased by the latter (through 25 % defoliation) . Defoliation up to 25 % reduced seed yield by only 2 %. Whereas the l evel of chlorophyll and aerial plant dry weight were not significantly changed by either kinetin or ABA, the level of protein and reduced ni trogen in the leaf and sugar level in both leaf and stem increased by kinetin. GA(3) increased almost all the parameters studied. All the th ree phytohormones increased the yield, mainly by increasing the sink s ize rather than the sink strength. It is concluded that the aerial flo wers are more lethal than the underground fruits in inducing whole pla nt senescence where the leaf senescence is uncoupled from fruit matura tion in normal condition possibly due to sink limitation.