Behavior of leaf nutritional status in ‘on’ and ‘off’ year bearing trees of ‘Bengal’ litchi (Litchi chinensis)

Abstract

The major problems reported in litchi in several countries include irregular flowering, poor fruit retention, small fruit size and alternate bearing. This study assessed the time course (all-year-round, on a monthly basis) of the leaf macro- and micronutrient concentrations, in ‘on’ and ‘off’ year bearing ‘Bengal’ litchi trees. In December 2012, fifty uniform trees, half of them with a heavy fruit load (‘on’ year) and the other half with a very light crop load (‘off’ year) were tagged to trace their nutritional status. The trees were twelve years old, with an approximately 5 m canopy diameter and 4 m in height, and have received the same cultural practices and fertilization since the orchard establishment. Leaves were sampled monthly from December 2012 to November 2013 and analyzed for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn) and boron (B). Data were submitted to analysis of variance and means compared by multiple range test at 5% probability. Leaf analysis showed differences between ‘on’ and ‘off’ year bearing trees for N, K, Mn and Cu. Leaf macronutrients were higher in the 4th month and lower around the 10th month, whereas leaf micronutrients were higher around the10th month and lower in the 4th month. These results open the possibility to use leaf analysis as a tool to predict potential yield and manage fertilization accordingly to minimize alternate bearing in litchi.