BORON IN CITRUS TREES

Open Access
Publisher Website
Google Scholar
Abstract
Gum was sometimes found in the peel of lemon and orange and also about the core in orange fruits produced by trees grown in soln. cultures lacking boron. The vessels of the woody tissues in such trees were often filled with gum; exudations occurred at cut surfaces and in some cases the gum protruded through the bark. Gum was exuded from the exposed surface of the pedicel when flowers or fruits were detached. It also occurred between the cells in leaves and was involved in leaf distortion. Translucent spots frequently preceded the corky splitting of leaf veins and often the terminal meristematic tissue or growing points in twigs were destroyed. No single symptom can be considered as characteristic or specific for B deficiency or excess. The turmeric method was found accurate and rapid for determining small amts. of B in citrus. It permits the fractionation of the B into soluble and insoluble portions in small samples and thereby avoids the interference of large amts. of gelatinous pectin. The B content of grapefruit juice is low in comparison with orange juice. The B content of Valencia orange fruits increased with age. The application of various amts. of B to the soil increased the water-soluble B content of the leaves of navel orange trees and of the fruit pulp. In dried citrus tissues, a large amt. of the B insoluble in distilled water was found to be soluble in weak acid. Decreasing the pH of the soil or increasing the deficiency of other elements such as N and K increased the accumulation of B in citrus leaves.