Effects of some plant growth regulators on leaves content of macronutrients in mango 'Haden'

The effect of some plant growth regulators on the macronutrients content in leaves of nine years old 'Haden mango trees on the different phenological stages were studied. The study was conducted at the College of Agriculture Experimental Station located at Maracay, Aragua state, Venezuela (10 degrees 16'N and 67 degrees 36'W, and 450 masl); in an area located in the Premountain Dry Forest, characterized by a mean temperature of 25 degrees C; an anual precipitation of 900 mm with a six month dry period, from November to April. The plant regulators used were Paclobutrazol (PBZ), Ammonium thiosulphate (ATS) and Potassium thiosulphate (PTS), in a complete randomized block design, with five replications, and using different concentrations as the treatments at different months periods. The treatmeants were PBZ at 10 mi of active ingredient (a.i) per tree to all experimental trees but the check. ATS at 0.5, 1.0 and 2.0 %; and PTS at 1.0, 2.0 and 4.0%. The ATS and PTS concentrations were applied 60 and 90 days after PBZ treatment. During the experiment, leaves for nutrient analyses were sampled every two months from the trees canopies. Orchard regular fertilization was done twice before flowering at 1.35 kg of Urea and 1.4 kg of KCI per tree. Results showed that there were statistically differences in the macronutrient content in leaves, depending on the phenological stage of the trees.