Standardization of leaf nutrient norms for 'Bombai' litchi (Litchi chinensis Sonn.)

Plants grow and absorb nutrients from the soil continuously and the best growth is usually associated with a particular nutrient concentration. A vast array of research has been conducted on litchi nutrition, although the results of much of it are of limited use to commercial producers. Leaf nutrient standards have been developed from Australia, Israel, India and South Africa, but they are based on different times of sampling. These standards form the basis of nutrition management. Several factors, namely, leaf age, position, climate, cultivar, season, etc., influenced the nutrient concentration in the leaves. We investigated the different factors to standardize the leaf sampling technique for litchi cultivar 'Bombai'. The concentrations of N, P, K, Ca, Mg, S, B, Cu, and Fe, in leaf varied significantly in different months whereas the variation of Mn and Zn was not significant. The N, P, K, Ca, Mg and S contents in leaf were higher between August and October while B, Cu, Fe, Mn and Zn contents were high in January-February. Leaves from vertical shoots contained higher amount of N, P, K, S, B, Cu, Fe, Mn and Zn while leaves from horizontal shoots showed more Ca and Mg contents. The N, P and K concentrations in leaf decreased as the leaf aged while Ca, Mg, S, B, Cu, Fe, Mn and Zn were found to accumulate on mature leaf. The concentrations of N. P, K, B, Cu and Zn were maximum in the leaf that was collected from the shoots projected towards the east side of the tree, whereas S, Fe and Mn were maximum in the leaf from shoots that were on the south side of the tree. The first and second pairs of fully expanded leaves for N, P and K and fifth and sixth pairs of leaves for estimation of Ca, Mg, S, B, Cu, Fe, Mn and Zn may be considered for understanding the nutrient status of the tree. The leaves should be collected from vertical shoots representing all four directions of the tree, in the month(s) of August and/or September for N, P, K, Ca, Mg and S and in the month of February for B, Cu, Fe, Mn and Zn for better monitoring of the tree nutrient status.