Sampling for mineral content in leaves of guava cultivar ‘Lucknow-49’

A continuous increase in dry matter content in leaves of guava (Psidium guajava L.) was observed when their age increased, and also from the base to the top of the shoot. While the N, P, K, Zn and Cu content decreased, the levels of Ca, Mg, Na and Mn increased when age of leaf increased. With regard to position of leaves on the shoot, the levels of N, Ca and Mg increased from base to top, while the reverse was true for P, K, Na, Zn and Mn. No definite pattern was observed for Cu. Stabilization of all constituents was observed in 5-months old leaves borne on position V from the base of shoot. Thus, while considering the nutrient status of a tree as a whole, leaves of this age and position should be sampled. However, in certain cases the range of period and position for leaf sampling varied with the different elements, e.g. for Ca, 1- to 2-months old leaves should be sampled, while for Mn, leaves should be taken from positions II–IV of the shoot.