Persea americana

Why are the seeds of this species difficult? This species has recalcitrant seeds, which have a high critical moisture content and will rapidly lose viability if they are dried. The seeds may have physiological dormancy, which can be overcome by mimicking the seasonal patterns of the species' native habitat.

Persea americana (Image: S. Wood, RBG Kew)

Seed Storage

This species has Recalcitrant seeds which cannot be dried without causing a decline in viability. Do not place the seeds under sub-zero temperatures as they will suffer from freezing damage due to their high moisture content.

The initial seed moisture status on collection is above 95% equilibrium relative humidity (65% moisture content). The seeds will remain viable for 2-3 weeks under ambient conditions, after removal from fruits. Provided they are not allowed to dry out, the seeds can be stored for up to 8 months in peat or damp sawdust at 4-5°C

The seeds can be safely dried to 57% moisture content without a loss in viability. Drying to below 49% moisture content causes a rapid drop in viability. Total viability loss occurs when dried below 34% moisture content.

Germination Requirements

Remove the seed coats to encourage quicker germination. Germinate on sand under an alternating temperature regime of 30/25ºC (with an 8/16hr photoperiod) or at ambient room temperature.

The seeds of this species may be Physiologically Dormant (based on other species in the same genus). If germination is low, overcome dormancy by mimicking the seasonal patterns of the species' native habitat. Use a moist pre-chill or pre-heat treatment (depending on local climatic conditions), before germinating the seeds on agar, germination paper or sand at their optimum temperature. If this does not work, you can perform delicate surgery to enable the embryo to grow. Excise the tissue near the root tip.

Seed Morphology

Persea americana seed
(Image: S. Wood, RBG Kew)

The fruit (7-20 cm) is a large, fleshy, single-seeded berry, pear-shaped or spherical in shape. The exocarp is variable in thickness and texture. The mesocarp has a butter-like consistency and is edible. The seeds are large and spherical with two large fleshy cotyledons, whitish or pink in colour, enclosing a small embryo.

See more images of this species at VIRBOGA (The Virtual Botanic Garden) and the Digital Atlas of Economic Plants.

Taxonomy

Family: LAURACEAE

Accepted name: Persea americana Mill.

Synonyms: Persea gratissima Gaertn.

Common name: avocado

References and Links

Baskin, C.C. and Baskin J.M. (1998). Seeds: ecology, biogeography, and evolution of dormancy and germination. Academic Press, USA.
Chirco E. and Turner T. (1986). Species without AOSA Testing Procedures. The Newsletter of the Association of Official Seed Analysts. Vol 60 (2) pp. 2-66.
Purseglove, J.W. (1968). Tropical Crops: dicotyledons. Longman Group Ltd., UK.

AFPD (African Flowering Plants Database) - Conservatoire et Jardin Botaniques de la Ville de Genève, Switzerland, and South African National Biodiversity Institute, Pretoria, RSA: Persea americana.
PROTAbase (Plant Resources of Tropical Africa) - Wageningen, Netherlands: Persea americana.
SID (Seed Information Database) - Royal Botanic Gardens, Kew, UK: Persea americana.
Tropicos - Missouri Botanical Garden, USA: Persea americana.