NUTRITIONAL INADEQUACIES OF GREENHOUSE TOMATOES

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.