How to Propagate Acerola Cherry? Detailed Guide to Propagation Techniques
Acerola cherry (Malpighia emarginata) is an evergreen shrub, or can be trained by pruning to develop a main trunk and become a small tree. A 10-12 year old plant can reach 4.5 m in height. The leaves are opposite, leathery and smooth, obovate to oblong, with entire margins, 3--10 cm long, and very short petioles. Their shape and size vary among cultivars. The inflorescences are cymose, with small 5-petaled flowers, usually pink or red, though there are also white-flowered lines. The fruit is a berry, resembling a cherry, but with three shallow grooves that make it slightly three-lobed. When ripe it is orange-red to purplish-red, with thin skin that is easily damaged, and contains three stones, each holding one seed.
Propagation methods:
1. Seed method
After harvesting acerola cherries, cut through the skin and flesh to remove the stones, wash off the flesh attached to the stones with clean water, then place them in a shady spot to dry for 1--2 days before sowing. When sowing, place the stones directly into a shallow pot, and they will germinate about 10--30 days after sowing. Once the seedlings reach 5--10 cm, transplant them into soft plastic pots. Acerola cherry seeds germinate easily, but germination is uneven, and the seeds produced by some plants often lack viable embryos, so the germination rate is often below 30%.
2. Cutting method
During the spring and summer growing season, select semi-mature, vigorous branches with a diameter of 0.7--1.2 cm, each segment 15--20 cm long, bearing 4--6 leaves. Insert them into river sand, vermiculite, peat soil, or a mixture of several of these, all of which are suitable as a seedbed medium. The cuttings especially need to be kept moist and shaded. To promote rooting, rooting hormone (IBA) treatment can be used. About 1.5--2 months after cutting, roots develop, and transplanting can be done after the root mass grows vigorously. If the cutting method is managed properly, the survival rate will be 60--90%.
3. Layering method
In horticultural practice, layering is a method for quickly forming a tree, but its effectiveness varies greatly among acerola cherry cultivars. Last spring, the author conducted an experiment on the two cultivars currently in the orchard, the sour type and the sweet type, using the ring-barking method, then wrapping with sphagnum moss and covering with plastic film, tied tightly above and below. The results showed that after layering treatment, the sour type had an 80% rooting rate within 1 month, while the sweet type, after a 3-month trial period, produced only callus tissue and no roots at all.
The above are the main propagation methods for acerola cherry. Although air layering roots relatively easily, its effectiveness varies greatly among cultivars and it is rather troublesome when propagating in large quantities, so it is rarely used in ordinary practice. The seed method reaches fruiting age relatively late, and quality variation among seedlings is great, so cuttings are generally used, as they are the simplest and easiest to succeed with.