Fruit yield and quality of twelve outstanding selections of guava (Psidium guajava']java) from the Calvillo-Canones region, Mexico

Guava is one of the main fruit crops cultivated in Mexico. There are 25,000 hectares planted with guava trees, with an annual production of 250,000 t of fruit. Most guava orchards are located in the states of Michoacan, Aguascalientes and Zacatecas at an altitude of 1200 to 1700 masl. The guava germplasm cultivated in the region is known as "media china" or "china"; however, there is great genetic and morphological variability within and among orchards. This variability of guava trees affects the uniformity and the quality of harvested fruits. Nevertheless, diversity of guava germplasm can be useful through selection and evaluation of outstanding material having comparative advantages to improve the productivity of this fruit crop. The objective of this study was to evaluate the agronomic characteristics of a group of selections from the guava ex situ collection of INIFAP. The experimental site is located at the Huanusco county in the state of Zacatecas, Mexico (21 degrees 44.7' N; 102 degrees 58.0' W and 1508 masl). The fruit yield and quality of twelve guava selections were determined during six years (1999-2005). Statistical analysis included ANOVA for total fruit yield, number of fruits per tree and fruit weight average. Simple regression analyses were also conducted between fruit number vs fruit yield and fruit number vs fruit weight average. Average of the six years for fruit yield and number of the twelve guava selections ranged from 33 to 62 kg/plant and from 636 to 1252 fruits/plant, respectively. Fruit weight average ranged from 37 to 76 g/fruit. Regression analysis showed a strong positive relationship (r = 0.91 **) between fruit number vs fruit yield. In contrast, the relationship between fruit number vs fruit weight average (r = 0.56 **) showed a tendency to decrease fruit weight as fruit number increased, suggesting that fruit thinning may contribute to improve fruit size. Alternance index for fruit yield varied from 32 to 83.5%. Outstanding guava selections showed a fruit yield from 2 to 4 times more than that obtained in the region of study. The availability of guava germplasm adapted to the main producing areas of Mexico showing high fruit yield potential and good fruit quality was determined.