Time of leaf sampling and analysis norms for mangoes (cv. Sensation).
Smith B. L.
Author Affiliation: Institute for Tropical and Subtropical Crops, Private Bag X11208, Nelspruit 1200, South Africa.
Yearbook - South African Mango Growers' Association 12 : 54-56
Abstract : Leaf samples were taken for analysis in Aug., Sep., Oct., Nov. and Dec. (when leaves were 4,- 5-, 6-, 7- and 8 months old, respectively) from N, P and K fertilizer experiments based at Friedenheim (5-year-old trees) and Hoedspruit (12-year-old trees). Polynominal regressions of the concentration of the elements N, P and K in the leaves with yield and fruit size over 5 seasons were carried out for each sampling month. Only N and K fertilizer applications correlated with yield, with the Nov. sample giving the best correlation. It was also found that the norms for young and mature trees differed. The results give optimum leaf N concentrations in the ranges 1.40-1.50% and 1.20-1.40% for mature and young trees, respectively. The norms for K were 0.85-0.90%. In both cases there was a marked tendency for yields to drop for K concentrations in excess of 1.05%.