Fruit-induced & apical senescence in Pisum sativum L.

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Abstract
Alaska peas, like many other annual plants, normally die as a result of fruit development. Gibberellin treatments delayed senescence by delaying fruit formation. Detachment of the seeds was almost as effective as removing the entire fruit in prolonging vegetative growth. When fruit development was prevented by deflowering or by gibberllin treatments, growth of the main stem continued only for a limited time. Ultimately the stem apex differentiated into a final flower and leaf and the apical meristem disappeared. Stem apices of young plants, grafted to tips of old plants, grew as rapidly and for as long a time as when grafted back to a young plant The old tips ceased growth even when grafted to a young plant. An old or young stem apex side-grafted to another plant did not substantially affect growth of the plant to which it was grafted. When individual lateral branches were allowed to develop, their growth rate was less than that of the old stem but duration of growth was substantially as long. It is concluded that apical senescence is due to some degenerative change taking place within the apex itself and is not translocated within the plant. Apparently, senescence of the apex is not directly related to the physiological onset of flowering. Apical senescence occurred even though no flowering took place.