Morphological and Phenological Evaluation of Ten Avocado Cultivars (original) (raw)

The Journal of Agriculture of the University of Puerto Rico

Avocado (Persea americana) belongs to the family Lauraceae. It is native to the tropical and subtropical regions of North and South America and has spread to all tropical countries in the world (Schaffer et al., 2013; Ayala-Silva and Ledesma, 2014). The avocado originated in Central America and southern Mexico. Based on archaeological evidence found in Tehuacan, Puebla (Mexico), it is believed to have appeared approximately 12,000 years ago (Yahia, 2011). The avocado tree is an evergreen that attains heights of 20 m, has many branches and produces edible fruits. Avocado cultivars are classified in three groups or races, known as the West Indian, Guatemalan and Mexican "races". Cultivars fall into one of two pollination types, referred to as type A and type B, the difference being the time of day (morning vs. afternoon) that the male and female flowers are capable of reproduction. Flowers of type A cultivars open in the morning as receptive females, then close in the afternoon until the following afternoon when they reopen for pollen shed. Type B avocado flowers open in the afternoon as receptive females, close overnight and reopen the following morning to shed pollen (Schaffer et al., 2013). West Indian avocados originated in the tropical lowland areas of southern Mexico and Central America whereas Guatemalan and Mexican avocados originated in mid-altitude highlands in Guatemala and Mexico (Figure 1) (Ayala-Silva and Ledesma, 2014). The fruit of avocado is referred to as a berry, consisting of a single carpel and a single seed (Schaffer et al., 2013). The fruit may be round, pear shaped or oblong, and the skin of the fruit may vary in texture and color. The skin of the fruit may be flexible to woody, smooth to rough, and green-yellow, reddish-purple, purple, or black in color. The flesh of the fruit is greenish yellow to bright yellow and buttery when ripe in good varieties, but in poorer cultivars may be fibrous. The avocado fruit has one large seed that makes up to 10 to 25 percent of the fruit weight. Avocado fruits range from 150 g to more than 1.50 kg in weight. Choice of cultivars must include many factors to determine the best available for commercial or home use. Soil type and location are quite variable and depend on the characteristics of rootstocks and disease resistance. Cultivars should be selected based on production and resistance to ailments (Knight, 1999) and climatic conditions; rootstocks (Ben-Ya'acov et al., 1992); and consumer requirements, such as minimum or maximum oil content and vitamins according to amended dry weight procedures (OECD, 2004). Further characteristics are size, color, peel roughness and shape, depending on