*In Vitro* Seed Germination and Seedling Development of Two Avocado Varieties

*Essoh Aimé Cesaire Elekou, Irene Perea-Arango, Luis María Suarez-Rodriguez and Rodolfo López-Gómez*

### **Abstract**

Avocado (*Persea americana* Mill.) is a tree native to central and eastern Mexico. A basal angiosperm of the Lauraceae family, it produces an oil-rich fruit that is appreciated worldwide for its nutritional value. Mexico is the world's leading avocado producer. Production is based mainly on the use of rootstocks of *Persea americana* var. drymifolia, a "Mexican native". The agronomic characteristics of the rootstock are key to avocado production. This work reports a germination method to obtain seedlings *in vitro* from two avocado varieties, *P. americana* var. drymifolia and West Indian *P. americana* var. americana. With this system, germination success rates of 100% were obtained in a maximum of five days, with homogeneous seedling development. This system could provide rootstock that improves the characteristics of agronomic programs and the selection of genetic material for avocado production.

**Keywords:** seed, *in vitro*, avocado fruit, *persea americana* var. drymifolia, cotyledon, seedling

### **1. Introduction**

The formation, dispersal, and germination of seeds are very important events in the life-cycle of gymnosperm and angiosperm plants [1]. As a member of the basal Angiosperms, the avocado tree, of the Lauraceae family, is considered by numerous botanists to be one of the most primitive dicotyledonous plants [2]. They are species of economic importance that are cultivated in tropical and subtropical areas worldwide [3]. Three botanical varieties (races) have been reported, known as Mexican, Guatemalan, and West Indian [4–6].

Latin America is the area with the highest production in the world, with Mexico being the largest producer [7]. The "Hass" cultivar has the highest consumer acceptance, production, and commercialization indices. This cultivar results from the hybridization of the Mexican and Guatemalan varieties [8], but cultivation requires rootstock from one of the botanical varieties, usually obtained from seeds [9, 10].

However, seedlings grown in nursery systems may require 40–60 days to germinate after sowing [11] and may lack uniformity due to the high genetic variation characteristic of seeds. Thus, various authors have reported the importance of shortening germination times and favoring this process using *in vitro* systems. Previous studies have reported 94−99% success rates in the germination of whole seeds and embryos barely covered by 1.5 cm2 of cotyledons in *in vitro* systems, with germination emerging at 3−10 days [12]. Various culture media compositions have also been evaluated with *Persea americana* var. drymifolia and *Persea americana* cv. Hass, reported average germination emergences of 20−27 days [13]. The advantages of *in vitro* germination may provide a solution to cases of the total inhibition of germination, foster increased germination rates, reduce the time required, and improve the homogenization of seedlings that can serve as rootstocks [14]. In this work, we report data on the germination and development of *in vitro* seedlings obtained from *P. americana var. drymifolia* and *Persea americana* var. americana.
