TheImprovement ofTropical and Subtropical Rangelands

176 IMPROVEMDIT OF TROPIOAL AND SUBTROPICAL RANGELANDS
shutting oft' the supplemental lights and by leaching excess nutrients
out of the potting media. Night temperatures are lowered, and
the seedlings are fertilized with a low nitrogen, high phosphorus and
potusium fertilizer. Drought stressing should be carefully monitored
becaWle overly dry potting soil may be difficult to rewet, and streBBed
plants may not cold-harden normally. In the final hardening stages,
temperatures are gradually lowered to the ambient levelj tolerant
plant species may even be taken slightly below DOC.
Hardening can be achieved in either a cold frame or a shadehouse.
Shadehouses are generally used to harden crops that are taken out of
the greenhoWle in summer or early fall when freezing temperatures
are not expected.
Planting Bare-Rooted Plants
Under ordinary circumstances, bare-rooted plants are used in
transplanting. Although such plants suffer greater 1088 and experience
a greater interruption in growth than do plants grown in containers,
the lower cost resulting from easier handling and transportation
may compensate for losses and interruption of growth under most
site and species conditions.
When planting stock has been properly wrapped, packed, and
stored at the nursery, some plant death may still be caused by operational
and natural hazards. Operational hazards include hauling
plants from the nursery to the field, storage at the planting project
area, and handling and planting practices in the field. Natural hazards
that must be considered are weather, animal damage, vegetative
competition, and insects and disease. Although natural hazards are
often beyond control, the operational hazards can be largely minimized
by careful planning, organization, training, and supervision.
Each of these hazards may be crucial in determining whether the
planting is a successj each must be carefully considered (Levin et al.,
1953).
Hauling plants from the nursery to the field would seem of little
dangerj yet speed in getting them to the planting site is essential to
achieving a high rate of survival. Wherever possible, stock should
be picked up at the nursery at frequent intervals to eliminate storing
plants for long periods in heeling-in beds in the field (Levin et al.,
1953). When packaged stock is hauled in an open truck, the shipment
should be covered with a canvas to protect against sun and wind.