A model for potassium nitrate-induced flowering in mango.
Protacio C. M.
Author Affiliation: Department of Horticulture, University of the Philippines, Los Banos College, Laguna 4031, Philippines.
: 545-552
Abstract : The possible mode of action of potassium nitrate on flower induction in mango is discussed. The model assumes that a tree sprayed with potassium nitrate is already competent to flower but is inhibited from doing so by gibberellic acid (GA). The inhibitory effect of GA probably arises from its ability to mobilize carbohydrates thereby preventing starch accumulation. Once GA levels fall below a threshold, starch can start to accumulate allowing the tree's competence to flower to be expressed. After sufficient starch has accumulated, floral initiation will ensue but remains quiescent until conditions favourable for flowering are achieved. Depending on the tree's N content and balance of growth regulators, floral development may continue or shift to a vegetative flush if tissues are not committed to floral development. Potassium nitrate probably acts by elevating N levels over an N threshold thereby synchronizing budbreak from apices with existing floral initials. The signalling process is probably mediated by polyamines or ethylene. Evidence from local as well as international studies is presented to support each component of the model.