Genetic Improvement of Guava (Psidium guajava): Utilization of the Diversity of Native Germplasm

Abstract

The guava (Psidium guajava L.) belongs to the Myrtaceae family and originated in the tropical and subtropical regions of Mesoamerica and South America. In Mexico, a great phenotypic and genetic diversity of this fruit crop has been reported. Guava is an important fruit crop worldwide. In Mexico, 21,127 hectares are cultivated, with an annual production of 300,000 tons. For the past three decades, INIFAP (National Institute of Forestry, Agriculture and Livestock Research) has conducted studies on the collection, characterization, and ex-situ conservation of P. guajava germplasm to obtain the greatest genetic diversity to be used in the genetic improvement and the development of new varieties with comparative advantages. Currently, INIFAP maintains an ex- situ collection of P. guajava germplasm, comprising approximately 100 accessions from various states across the country. This collection includes information on the morphological characteristics of the fruit, revealing a wide range of diversity. Simultaneously it was carried out an evaluation and characterization of a group of outstanding selections from the Calvillo-Cañones region, from which the first five clonal varieties were derived and registered in the National Catalog of Plant Varieties of the National Seed Inspection and Certification System (SNICS). The registered varieties and their main fruit characteristics are: 1) Calvillo Siglo XXI: ovoid fruit, cream pulp, with a mesocarp thickness of 6 to 8 mm and a °Brix content of 12 - 14; 2) Huejucar: ovoid fruit with pale pink-cream pulp, mesocarp of 7 to 8 mm and °Brix of 12 - 14; 3) Hidrozac: truncated fruit, pink pulp, mesocarp of 10 to 12 mm and °Brix of 11 - 13; 4) Caxcana: round fruit, white-cream pulp, mesocarp of 8 to 9 mm and °Brix of 11 – 13; 5) Merita: ovoid fruit, cream pulp, mesocarp of 7 to 8 mm and °Brix of 12 – 14. These varieties have shown fruit yield greater than 15.0 tons ha^-1, which is the average obtained at the national level.