Optimal leaf norms for young and old mango trees.
Smith B. L.
Inligtingsbulletin - Instituut vir Tropiese en Subtropiese Gewasse :6
Abstract : In 2 N and K nutrition trials (at the Friedenheim Experimental Farm and at Hoedspruit), mango cv. Sensation leaf samples were analysed in Aug., Sep., Oct., Nov. and Dec. (when leaves were 4, 5, 6, 7 and 8 months old, respectively) for 7 seasons. Polynomial regression analysis showed that the norms for young trees (first 4 seasons of production) were 1.25-1.40% N and 0.90-0.98% K, while for mature trees (?10 years old) the norms were 1.25-1.50% N and 0.90% K. The 7-month-old leaf sample gave the best correlation between leaf N and fruit yield. Increasing rates of N application resulted in an increase in leaf N content associated with a decrease in fruit size.