COLLECTION AND CHARACTERIZATION OF MEXICAN GUAVA (PSIDIUM GUAJAVA L.) GERMPLASM

The origin of guava (Psidium guajava L.) is believed to be in the tropical areas of America. From here, it was spread to Europe and Asia where it currently plays an important role among other tropical fruits. Mexico is considered a primary center of diversity of this species, and it can be found as a native crop in almost all parts of the country. In Mexico, guava is commercially cultivated on more than 23,000 hectares, and the principal guava cultivar Media China is very similar in the main producing areas. For this reason, it is important to collect, characterize and use outstanding materials having comparative advantages such as fruit size and form, external/ internal color, seed number, pulp thickness, vitamin C content, and others. Thus, a germplasm collection was established to increase the genetic base of guava by an ex situ conservation strategy. This collection was conducted in 11 Mexican states covering regions from 0 to 2000 m.a.s.l. and including native, backyard and cultivated germplasm. Most of the material was collected as fruits, from which seedlings were developed and established in August 2005 and March and July 2006 under field conditions. During the growth season of 2008, several guava trees started their reproductive stage and produced some fruits. A sample of those fruits was characterized according to UPOV descriptors. The collected material showed a great fruit variability with respect to form, size, pulp and skin color, pulp thickness, seed number, etc. These first findings underline the important richness of P. guajava germplasm in Mexico and provide prospects for the development of new cultivars.