Agricultural Science Digest

Vol. 9, Sept. - Oct., 1966

TOMATO SEEDLINGS
RESPOND TO PHOSPHORUS

Tomato seedling growth rate for the first
28-35 days after emergence was highest when
phosphorus was placed on the seed, banded
directly beneath the seed or in combinations
of banded plus broadcast applications.

In the experiments, when the band was
placed 11/2 inches to the side and 2 inches
below the seed, very slow growth rates were
obtained.

Trials were conducted with phosphorus
banded on the seed at the rate of 5 pounds per
acre or 2 inches below the seed at the rate
of 20 pounds per acre. Both treatments, tried
with and without extra phosphorus mixed in
the soil, resulted in optimum tomato seed-
ling growth rates.

Adding potash to the band under the seed
did not affect growth rate.

In summary, the research pointed out
that the phosphorus requirement of tomato
seedlings can be satisfied by a relatively
small rate of phosphorus fertilizer if it is
placed so it dissolves in the soil solution
near the seedling root system. A much high-
er broadcast rate would be needed to produce
the same phosphorus concentration in the
soil solution occupied by seedling root sys-
tems.

If phosphorus concentration is the criti-
cal factor in supply, the 5 pounds added on the
seed would be as effective as 500 pounds
broadcast and mixed in the plowlayer for
starting the plant.
Journal Paper 2875, Gerald E. Wilcox,
Horticulture Department.

SUNFLOWER MOVEMENT
STUDIED BY SCIENTISTS

On a fine day a young sunflower plant
always turns toward the east in the morning
and west in the evening with the movement
of the sun. Little or no movement is ob-
served during rainy or cloudy days. Horti-
culturists designed experiments with sun-
flowers in a controlled environmental cham-
ber to determine how the sunflower move-
ment occurs.

In the first experiment, four groups of
plants were chosen for their uniformity of
size of leaves and straight stems. Plants in
the first group were placed in a dark room
and the others were placed in the growth
chamber. The second group was unshaded,
the third group had the leaves on the left
side of each plant covered with aluminum foil,
and the fourth group had the right leaves
covered.

After five hours, the curve of the stems
was recorded by the scientists with these
results. Apparently when one of the leaves
was covered with aluminum foil the plant al-
ways turned away from the shaded side.
However, when both left and right leaves
were exposed either to light or dark no stem
curvature^ was observed. Under natural con-
ditions, in the morning or evening, the leaves
more distant from the sun receive less in-
tensive light just as do those covered with
aluminum foil.

Three other groups of plants were grown
in dark, in light and with one leaf darkened.
Stems were marked with India ink just below
each of the leaves. Growth during 24 hours

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