Glossary - Afforestation, Reforestation and Forest Restoration in Arid and Semi-arid Tropics - page 272

high cation-exchange capacity. It is expressed in mEq per litre. RSC should not be
higher than 1 and should preferably be less than 0.5 for considering the water use
for irrigation.

Reverse slope In bench terraces or gradoni, slight slope kept inward to the hillside
so that soil and water are retained for longer on the terrace.

Rhizome An elongate, horizontal, subterranean plant stem that is often thickened
by deposits of reserve food material, produces shoots above and roots below, and is
distinguished from true root in possessing buds, nodes, and perhaps scale-like leaves.

Rhizosphere Soil that surrounds and is influenced by the roots of plants.

Ring trench A trench in shape of a ring dug at head of a gully to prevent water from
eroding it further, or around a plant in field to collect water and supply it to the plant.

Riprap A layer of stones or chunks of concrete thrown without order in a layer on
embankment slope to prevent erosion.

Rodents Animals of order Rodentia, small mammals characterised by gnawing
habits, such as mouse, squirrels, or beavers, that have in both jaws a single pair of
incisors with a chisel shaped edge. Sometimes, a small mammal like rabbit or shrew
is also referred to as a rodent.
Root pruning Pruning of roots, especially of the overgrown roots emerging out of
the pot, in order to encourage development of a compact fibrous root system.

Root suckers Shoot rising from the root of a woody plant. Also called sucker.

Rooting hormones Chemical substances that stimulate growth of root from the
vegetative part of a plant.

Root-shoot cuttings Cuttings prepared for plant production in nursery, or for plant-
ing out in field, consisting of part root and part shoot portion of a plant. Such cuttings
result in a superior plant with a strong stem that is likely to grow straight and produce
good timber. Also known as stumps, or stump cuttings.

Root-shoot ratio The ratio of the total mass of a plant contained in the roots to that
in the shoot. The concept is useful in defining balanced development of a healthy
plant in nursery. If growth of roots is constrained and the root mass is small compared
to the shoot, the plant roots may not be able to meet the larger shoot's demand of
nutrients when it is planted out in field.

Rootstock The remnant vegetation in a degraded tract of land, chiefly consisting of
roots of native plants with most of the shoot portion having been grazed or destroyed.

Rose can A can fitted with a spout ending in a circular piece of perforated sheet so
that water can be evenly sprayed over plants in nursery to avoid dislodgement of soil
particles while watering.