AGROMORPHOLOGICAL CHARACTERIZATION OF TOMATO SAMPLES FROM OAXACA

Abstract

Tomato breeding programs generally manage a narrow genetic base, and thus it is necessary to explore and identify the natural genetic variation of this specie as a source of genes for improving productivity, improving adaptation, and solving pest and disease problems. To characterize the agromorphological variation of a collection of both wild and semidomesticated tomatoes (Lycopersicon esculentum var. cerasiforme Dunal) from the state of Oaxaca, México, 49 populations were collected and characterized under greenhouse conditions. Significant differences among populations were detected in all evaluated traits except for days to fruiting on the fifth raceme. Principal component analysis showed that days after transplant to blossom initiation, fructification ripening, number of fruits on the fifth raceme, plant height at 30 d after transplant, fruits per raceme, and average fruit weight were the most important traits for describing morphological variability. Cluster analysis revealed the existence of two large groups, one for the wild and another for the semi-domesticated tomatoes. The first group consisted of four subgroups of variants with pear-shaped or rounded-flattened fruits with 3 to 5 locules, 2.5 to 3.7 cm in diameter and 2.6 to 3.1 cm in length. The second group joined populations with smaller fruits, indicating their wild condition, fruits with two locules, fruit diameter and length less than 2 cm, high production of flowers per raceme (5 to 7) and 20 to 30 fruits at the fifth raceme, precocity for fruiting at the fifth raceme (53 to 55 d after transplant) and indeterminate growth (1.3 to 1.7 m at 60 d after transplant). There is important variation in Oaxaca regarding phenological, plant, stem, leaf, flower and fruit traits in both wild and semi-domesticated populations of tomato.