Magnesium, Manganese and Zinc Sprays on Orange Trees (Citrus Sinensis (L.) Osbeck)

Abstract

Deficiency of magnesium, manganese and zinc is quite common in citrus trees in Chile. In order to correct these deficiencies either simultaneously or individually, a trial was done in two “Valencia” orange groves located at Peumo, 150 kg South West from Santiago. Orchards were 37 and 12 years old and showed moderate deficiency of the three elements. In older trees, sprays of magnesium sulphate, manganese chelate, zinc sulphate, zinc chelate and mixtures of the three elements were done twice, November 1981 and October 1982 (mid spring, after fruit set). Each treatment was replicated five times in a randomized design with one tree per plot. In the young orchard only two treatments were tried.

Manganese deficiency symptoms were corrected with most treatments containing this nutrient, but correction was faster with sprays of the three elements mixed in the solution. Magnesium deficiency symptoms were partially controlled only with magnesium nitrate, while zinc symptoms were not corrected. Leaf levels of manganese and zinc were significantly increased in those trees treated with manganese sulphate or chelate. The level was higher, even in the leaves developed after the sprays the same season but not the following season. Trees sprayed with a mixture of magnesium, manganese and zinc sulphates, showed a lower manganese and zinc content in leaves than trees sprayed with manganese or zinc sulphates alone. This reduction did not occur with chelates. Leaf level of magnesium was moderately increased by magnesium nitrate sprays. In old trees, vegetative growth and fruit quality were not affected by treatments. Sprays in younger trees showed a moderate tendency to increase vegetative growth, and soluble solids in juice.