MORPHOANATOMICAL LEAF ANALYSIS IN HORTICULTURAL GROUPS OF AVOCADO (Persea americana) PLACED AT INIA-CENIAP’S COLLECTION, VENEZUELA

Abstract

The avocado (Persea americana Mill.) is the most important species of Lauraceae in America due to its exploitation as food for pre-Columbian and modern cultures. It is a very important seasonal crop in Venezuela based on a perennial fruit tree management. From a selection of 76 accessions (45 cultivars) of avocados cultivated at the Germplasm Bank of INIA-CENIAP, a morphoanatomical analysis was performed to identify attributes of taxonomic resolution (diagnostic characters) which allow to characterize sets and / or culta. Morphological study was carried out from each accession herborized sample. Information was obtained by freehand transverse leaf sections (epidermis, mesophyll and midvein) as well as paradermic preparations, and observed data was recorded in DELTA System. New morphoanatomical characters and discriminating attributes between cultivars were identified and described, especially to discriminate the Mexican group, and a close relationship within West Indian and Guatemalan cultivars was observed due to the variability identified from the latter group. Indument- related attributes were highly informative to discriminate among cultivars, along with the outline, apical angle and projections at the base of the leaf blades, stem cross section and presence of anise odor, progress and joining of the secondary nerve branches, tertiary venation pattern, abaxial contour and thickness of the sclerenchymatous sheath and compaction of the phloem in the vascular bundle, adaxial contour of the median nerve, and thickness, outline and uniformity of the anticlinal walls of adaxial and abaxial epidermal cells.