GENETIC VARIABILITY IN CULTIVARS OF GUAVA (PSIDIUM GUAJAVA L.)

Abstract

The genetic and morphological variability of 17 guava (Psidium guajava L.) genotypes from the States of Nayarit, Chiapas, Morelos, Zacatecas, Michoacán, Tamaulipas and Veracruz in México, and from Brazil, were evaluated. The genotypes were studied by obtaining RAPD (Randomly Amplified Polymorphic DNA) patterns. Of 226 bands evaluated, 84.07 % were polymorphic. The cluster analysis of RAPD detected a maximum genetic similarity of 91.3 % among the genotypes MOR9 and MOR10 from Morelos, and a minimum similarity of 41 % between the genotypes JROS22 and PAL8 from Michoacán and Brazil, respectively. Of the 40 morphological variables measured, ten of them make a strong contribution to the genotypic variability: longitude of petioles of small and big leaves, angles of the 3rd rib of small and big leaves, angles of the 5th rib of small and big leaves, forms of small and big leaves, bend of traverse section of small and big leaves. The dendrogram generated of 15 guava genotypes by utilizing morphological traits and the Ward method of cluster and euclidian distances, showed that genotypes are grouped according to their geographical origin. This result agrees with the groups formed by utilizing RAPD markers.