Genetic Diversity among Local and Introduced Avocado Germplasm Based on Morpho-agronomic Traits

摘要

Appreciating the nature and extent of variability among avocado {Persea americana Mill.) genotypes for traits of economic importance are essential to plan effective breeding and germplasm conservation programs. This study was undertaken to estimate the existing genetic diversity within and among some local avocado germplasm collections kept at the University of Ghana Forest and Horticultural Crops Research Centre, Kade based on agro-morphological traits which included leaf shape, colour and leaf margin, tree shape and trunk surface, fruit shape, fruit habit, fruit apex shape, ridges on fruit, pedicel position on fruit, gloss of skin as well as fruit number and fruit weight. A total of one hundred and one (101) local landraces collected from different ecozones of Ghana were studied in Experiment 1 while in Experiment 2, five (5) introduced world leading varieties obtained from South Africa and thirteen (13) selected lines in Experiment 1 were used in the studies. The five introduced and exportable varieties are 'Hass', Tuerte', 'Ryan', 'Ettinger' and 'Nabal'. Morphological characterization of the germplasm using the plant descriptors outlined in the IPGRI publication, Descriptors for Avocado {Persea sp.) have been described. The results indicated genetic diversity among the avocado lines and cultivars in terms of leaf, tree, fruit and yield characteristics. Spearman's rank correlation coefficient revealed significant positive correlations among plant height, canopy width, stem girth and number ofbranches. Future improvement of the crop plant should exploit the genetic variability available in the newly introduced world cultivars as well as the local germplasm collections.