Introductory Agroforestry

REGENERATION

Natural regeneration

• Acacia catechu reproduces naturally through coppice as well as from seed.
• The coppicing power of the trees depends upon their age, vigour, season of cutting and site conditions.
• In its stands of normal growth and stocking, coppicing can be relied upon to regenerate this species. Such stands are worked under coppice system.
• The stocking of the coppice crop, which depends upon the stocking of the natural crop coppiced and the coppicing power of the trees, is generally irregular.
• Coppice regeneration has therefore to be supplemented by artificial regeneration.
• Coppicing cannot be relied upon in selection stands where Acacia catechu grows mixed with other species as the light sufficient for the development of coppice shoots dose not reach the ground in such forests.
• Under heavy shade the stools normally do not coppice.
• The stand having over mature trees also cannot be regenerated through coppice because of the weak coppicing power of such tree.
• It has, however, been observed in some areas that the size of the stump does not affect the coppicing power and the stumps up to 60 cm diameter not only coppice well but also produce healthy coppice shoots.
• The growth of crop is faster than that of the seedlings crop; an average girth of about 20 cm and an average height of about 3.4 m can be expected for nine years old coppice.
• Coppice crop, however, requires thinning of stool to reduce the competition which may otherwise very adversely affect the growth rate of coppice shoots.
• Natural regeneration through seed can be expected under favourable conditions only.
• Seeds, are disseminated by wind. Germination takes place with the onset of monsoon rains and the seedlings get established where conditions are favourable for their growth.
• Soil type, drainage, weed competition, shade and grazing are important factors determining the success of natural regeneration through seed.
• Poor drainage coupled with shade results in heavy mortality of the seedlings because such conditions encourage damping-off. Tall and gregarious weeds compete out the seedlings.
• Grazing does not permit any natural regeneration to establish as the seedlings are browsed and killed. Profuse natural regeneration may be expected in areas kept free of grazing.
• It may be totally absent in grazed areas.
• The growth of seedlings in naturally regenerated crops is slow and they often die-back in winter

Artificial regeneration

Acacia catechu can be propagated by one of the three methods, namely (1) direct sowing, (2) planting out nursery raised seedlings and (3) stump planting. Direct sowing is better than stump planting, which is preferred to planting out of entire plants without containers.

i. Line/strip sowing in lines 60 to 90 cm apart, strips 2.5 to 3 cm apart.
ii. Broadcast sowing in weed free area.
iii. Patch sowing by dibbling 2.5 to 3 cm apart.
iv. Potted plants or with ball of earth.

Seed collection and storage

• The seed ripens in November-December or early January
• Seeds are very susceptible to insect attack even when on the trees and the pods should, therefore be collected shortly before the seeds are fully ripe as otherwise most of seed crop may be destroyed by insects.
• The pods are dried in the sun and then thrashed to separate the seed which is properly cleaned, dried in the sun and stored in airtight tin containers. The seed should preferably not be stored for more than 6 to 8 months under ordinary conditions;
• The seed should preferably be sown during the year of its collection. As Acacia catechu is a good seeder, there should be no problem in the collection of sufficient fresh seeds every year.
• About 30 to 40 seeds weigh one gram.
• Seed yield per tree is about 0.5 to 2.0 Kg.