Agriculture Reference
In-Depth Information
Optimum
range
“Luxury
“Hidden hunger,”
symptoms may
not be obvious
consumption”
Severe
deficiency,
marked visual
symptoms
Critical
value
Tissue N concentration (%)
Relationship between yield and nutrient concentration in plant tissue.
Figure 5.2
a deficiency or toxicity suggested by visual symptoms. Midsummer sampling (at
veraison) is also used to check on any doubtful results from an earlier sampling.
Leaves must not be sampled soon after any foliar spray has been applied.
Plant Part
. Because remobilization of elements is possible within the plant,
the part to be sampled must be specified. A leaf consists of a blade, or lamina,
and a petiole. Leaves are plucked from opposite flower bunches near the base of
a shoot, about the fourth or fifth leaf from the base (referred to as “basal leaves”),
Box 5.1
Morphological and Physiological Stages of Shoot Growth and Grape Ripening
Bud burst:
Bud dormancy is broken and young leaves begin to emerge and expand
in spring (early October or early April in cool climate regions of the Southern
and Northern Hemispheres, respectively).
Flowering (or bloom in North America):
50% or more of the grape bunches or
clusters are in flower; can extend over several weeks in cool climates; cell
division begins in the fertilized flower.
Fruit set:
50% or more of the bunches have berries that are 3-5 mm in diameter;
all unfertilized berries should have been shed. From fruit set to veraison, berry
growth is mainly by cell division.
Veraison:
The berries begin to soften and change color—a sign of ripening.
Midveraison is when 50% of the bunches are coloring (for red grapes). After
veraison (postveraison), berry growth is mainly by cell expansion (through
water and solute accumulation).
Maturity:
Full ripeness attained; bunches are harvested.
Post-harvest:
Vines continue to grow, especially through root growth, provided
temperature and soil water are adequate.
