C.M. Protacio
An explanation of the potassium nitrate effect on mango flowering within the framework of developmental biology concepts is presented. This model redirects our fascination with a flower stimulus to one where an inhibitor controls flowering. 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 enough starch has accumulated, floral initiation will ensue but remains quiescent until conditions favorable for flowering are achieved. Depending on the tree's nitrogen content and balance of growth regulators, floral development may continue or shift to a vegetative flush as the tissues are not yet determined or committed to a floral development program. Potassium nitrate probably acts by elevating nitrogen levels over a nitrogen threshold thereby synchronizing budbreak from apices with existing floral initials. The signalling process is probably mediated by polyamines or ethylene. Corraboratory evidence, from local as well as international studies, are presented to support each component of the model.
Protacio, C.M. (2000). A MODEL FOR POTASSIUM NITRATE-INDUCED FLOWERING IN MANGO. Acta Hortic. 509, 545-552
DOI: 10.17660/ActaHortic.2000.509.62
carbohydrate, gibberellic acid, nitrogen content

Acta Horticulturae