PHENOTYPIC DIVERSITY OF APPLE IN ZACATLAN, PUEBLA, MEXICO IS BROAD AND IS GIVEN MAINLY BY FRUIT TRAITS

The apple (Malus spp.) is a fruit tree distributed worldwide, with more than 30 species and almost 1000 cultivars. The municipality of Zacatlan, at the Sierra Norte of Puebla, Mexico is the main producer in the state and is recognized by its tradition in the cultivation and use of this fruit, as well as by the abundance and variability of cultivars, among which 'local' or 'traditional' varieties stand out. Nevertheless, this regional diversity has not been characterized; therefore, this study aimed to identify the phenotypical variation present on a sample of apple trees from the municipality of Zacatlan, employing in situ characterization. For this purpose, during the years 2015 and 2016, in eight orchards, located at five localities, 103 trees from 36 cultivars (24 'traditional' and 12 'recently introduced') were characterized using 49 traits, including morphological traits from fruit, flower and leaf, fruit biochemical traits and tree attributes. The data were subjected to one-way analysis of variance, as well as to multivariate analysis (principal component, cluster, and analysis of variance). There were significant differences among trees in 100 % of the analyzed traits, among which, 16 variables from fruit, flower, leaf and tree (which included 12 morphological, two biochemical and two phenological traits) were the most important in explaining the observed variation. Five groups, representing the diversity in the municipality, were defined, and they were statistically different from each other in nine out of the 16 traits: luminosity value of the skin and flesh, lenticel number, fruit firmness, sepal width, flower color at bloom stage, petiole length, days to the start of harvest and Brix degrees. It is concluded that in a small area, such as that of the municipality of Zacatlan, Puebla, there is a wide diversity in apple trees.