Nursery Techniques - Afforestation, Reforestation and Forest Restoration in Arid and Semi-arid Tropics - page 32

latter, which can consist of a large number of species and varieties, can be purchased
from the market.
While collecting seeds locally, great care should be taken to select the right prove-
nance and the plus trees. Choice of the provenance is determined by the site conditions
of the area to be afforested. In the stands of the selected provenance, the plus trees
should be carefully identified, marked, and recorded in the nursery journal. Sufficient
number of plus trees should be identified for each species to meet the annual seed
requirement of the nursery. If such trees are in privately owned fields, contractual
arrangements can be made with the owner for annual harvest of the seeds, although
the actual work of seed collection should not be given out on contract.
To purchase or to collect seeds, it is necessary to compute the required quantities.
Factors like germination percentage, number of plants to be raised, and amount of
losses involved, all will affect the quantity of seeds. Number of seeds per kilogram
is what determines the quantity in kilograms. It is convenient to have a seed weight
chart handy while computing this.
Different species have different seeding time, and therefore, it will be necessary
to have a timetable for collection or purchase of seeds. Many seeds have a short
viability and therefore cannot be used once the sowing time has been missed. Seeds
with long viability can be purchased at one go and an appropriate multi-season or
multi-year stock may be maintained.
Quality of seeds should be doubly ascertained from the source of collection and
also by inspecting their physical condition. Fresh and mature seeds will be of bigger
size than the average, have a clean and shining surface, and will be free from trash.
Many varieties will sell in market only in pod form and not in clean seeds form. Such
pods should be broken and clean seeds should be isolated and checked carefully.
Finally, seeds may be put to an in-house germination test or sent for a laboratory
germination test.
Storage of seeds has to be carefully considered. It is useful to think of seeds as
drugs in a drugstore: each should have a date of collection or procurement and a
date of expiry. For this, it is a good practice to package seeds in polypots or other
transparent bags and to label these with species name, weight, and dates as above.
The bags should be punctured at a number of places to allow aeration. Expired seeds
or unnecessary seeds should be discarded periodically, as these can create confusion,
and many a time can lead to a wrong batch going into the nursery. Often it is desirable
to keep index samples of all the varieties of seeds to make it easier to recognise seeds
of various species. Expired seeds can be put to this use, provided their appearance
has not changed significantly.

2.5 Procurement of Manure, Clay, and Sand

Quality of the potting mix (soil medium) to be filled in containers affects the growth
of plants. Sometimes the soil in or near the nursery site is fertile enough to be used
for filling in polypots, but such occasions could be rare in arid and semiarid tropics.
Often potting mix will have to be designed and prepared if quality of plants is to be