FENOLOGY AND NUTRIMENT AL DYNAMIC OF MEXICAN PLUM LEAVES

Abstract

Phenology and nutrient status of a rainfed coriunercial orchard of Mexican plum Spondias purpurea L.) (Gorda amarilla type) were studied through an annual cycle. During the tree vegetative stage (May to October), leaf growth and foliar content of N, P, K, Ca, and Mg were analyzed at monthly intervals. Mexican plum underwent defoliation in the fall, and dormancy, during most of the winter season, in contrast to most tropical and subtropical fruit trees. Flowering and fruiting processes occurred when the trees were in the
defoliated stage. Vegetative growth was detected after the beginning of the harvest season and it finished in October, with the first symptoms of defoliation, which preceded dormancy. Leaf growth expressed as dry matter and length, showed a double sigmoid curve. Leaf N, P, K, and Mg concentrations decreased with leaf age through September, when leaf growth had finished, while calcium increased. Based on these results, September is the the most suitable time for leaf sampling for diagnostic purposes. Comparison of the results obtained for the September leaf sample from the Mexican plum orchard to nutritional standards considered optimal for stone fruit trees, revealed that levels for N, Ca and Mg were adequate, but P and K were below the optimal range.