Glossary - Afforestation, Reforestation and Forest Restoration in Arid and Semi-arid Tropics - page 270

Planting pits Pits dug in field for planting. Pits benefit plants in many ways, chiefly
by providing loose porous soil for easy root penetration and increased water holding.

Plantlet A very small plant, especially one that stands in a seedbed. ⇒ Prickling.

Plus trees Trees identified as of superior phenotype and possibly of superior geno-
type. Such trees are used as a source of plant material, such as seeds and cuttings,
for propagation purposes.

point-to-point watering ⇒ Spot irrigation.

Pollarding The practice of cuttings back a tree to the trunk to promote growth of a
dense head of foliage.

polybed ⇒ Bed

Polyethylene One of the various partially crystalline lightweight thermoplastics
with the generic chemical composition of (CH 2 CH 2 ) 2 , that are resistant to chemicals
and moisture and are used in packaging and insulation.

Polypots Tubes made of polyethylene, usually LDPE, and sealed at one end to be
used as pots in nursery. In nurseries with large-scale production of containerised
plants, the polypots have proved to be the most economic, versatile, and convenient
containers.
Polythene

⇒ Polyethylene

Polyvinyl chloride A polymer of vinyl chloride used in manufacture of pipes and
other articles. More familiarly known in its abbreviated form PVC.

Pot-bound The state of a potted plant when roots have become so densely matted
that there is no further scope for growth.

Potting Putting a plant into a container.

Potting mix Mixture of earth and manure with a good level of fertility and drainage
to be used as a medium of growth for plants to be grown in pots.

PRA ⇒ Participatory rural appraisal.

Precedence relationship The relationship among different activities in a project,
describing the temporal order in which the activities must be executed.

Pricking out The process of removal of the young seedlings from one seedbed to
another, or from a seedbed to containers, for further growth.

Prickling A seedling in a seedbed fit to be pricked out.

Production forestry The practice of growing trees with the specific aim of produc-
ing economic worth rather than as land conservation or amenity.

⇒

Conservation

forestry.
Production ratio In a nursery plant production plan, the ratio of the number of
pieces of plant materials to the number of plants produced finally. This ratio is always