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| Greenhouse tomatoes |
As we know that greenhouse tomatoes depend on the
farmer to get all the nutrients needed for efficient growth and development.
Therefore, it is very important for farmers to provide all these nutrients in
the required amount to the crop to get optimal yields. Moreover, the farmer should
also be aware of signs and symptoms the plants show to nutrient imbalance or
inadequacy in the greenhouse for efficient management. Below are some common
nutritional inadequacies of greenhouse tomatoes;
High
Nitrogen: common to soilless greenhouse tomatoes,
it is possible for the nitrogen supplied to the tomatoes to be more than what
is required by the plant for proper growth. However, this excessive nitrogen
causes the tomatoes to grow vegetatively which may reduce the production of
fruits. Some of the symptoms showed by the tomatoes include:
curling of the leaves terminal, fruits per cluster will be reduced.
Nitrogen
deficiency/inadequacy: this result in
stunted growth of the tomatoes and yellowing of the leaves which later
defoliate.
Phosphorus
deficiency: this is evident in tomatoes when the
leaf turns purple.
Potassium
deficiency: Mature, lower leaves first show marginal yellowing, followed by
desiccation (burning) of the tissue along the margins.
The
symptoms progress both inward on the leaf and upward on the plant as the
deficiency becomes more severe. The fruit will often ripen unevenly or will show
blotchy green to yellow patches.
Calcium
deficiency: this results in chlorosis of the plant
and dieback of the growing points. It also prevents the growth of lateral shoots
and shortening of the internodes.
Magnesium
deficiency: it causes interveinal chlorosis (yellowing between the veins), which
starts in the older leaves and proceeds toward the younger leaves as the
deficiency becomes more severe.
Sulphur
deficiency: similar to nitrogen deficiency in that older leaves become yellowish-green
and stems become thin, hard and woody. Some plants may show a colorful orange
and red tint rather than yellowing. The stems, though hard and woody, increase
in length but not in diameter.
Iron
(Fe) deficiency: it starts as a yellowing of the immature leaves and growing
points. As it progresses, this tissue may turn almost white.
Manganese
(Mn) deficiency: it starts with interveinal
chlorotic mottling of the immature leaves. Sometimes, it is indistinguishable
from iron deficiency in some plants. As the deficiency becomes more noticeable,
necrotic spots usually appear in the interveinal tissue. Sometimes bloom buds
on the flowering clusters show incomplete growth and do not develop.
Zinc
(Zn) deficiency: In some plants, interveinal chlorotic mottling first
appears on the older leaves, and in others, it appears on the immature leaves. It
is very similar to the symptoms showed by manganese deficiency.
Boron
deficiency: Symptoms include slight chlorosis to brown or black die-back of
the growing points similar to calcium deficiency. The die-back tissue is usually
very dry, brittle and easily crumbled.
Copper
deficiency: it causes the leaves
at the top of the plant to wilt easily. This is usually followed by
chlorotic and necrotic areas in the leaves. Leaves on top of the plant
show unusual puckering with veinal chlorosis. Splitting of ripe fruit,
especially under warm temperatures, is an indication of low copper.
Molybdenum
deficiency: The older leaves show interveinal chlorotic blotches, and become
cupped and thickened. This deficiency is very seldom seen in greenhouse
tomatoes.
In addition
to the above deficiency symptoms, a deficiency of one micronutrient can result
from an excess of another thereby causing nutrient imbalance. Also, temperature
and pH can affect nutrient solubility and concentration. Recycling nutrient
solutions can create an imbalance in the stock nutrient solution.
REFERENCES
Alvin D. Rutledge. Pub. 1609. Commercial Greenhouse Tomato Production. Agricultural Extension Service. The University of Tennessee
Snyder, Richard.
Pub. 1828. Greenhouse Tomatoes. Cooperative Extension Service. Mississippi
State University.
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