Sulfur deficiency in tomato plants

This leaf shows a general overall chlorosis while still retaining some green color. The veins and petioles exhibit a very distinct reddish color. The visual symptoms of sulfur deficiency are very similar to the chlorosis found in nitrogen deficiency. However, in sulfur deficiency the yellowing is much more uniform over the entire plant including young leaves. The reddish color often found on the underside of the leaves and the petioles has a more pinkish tone and is much less vivid than that found in nitrogen deficiency. With advanced sulfur deficiency brown lesions and/or necrotic spots often develop along the petiole, and the leaves tend to become more erect and often twisted and brittle.

Whenever the S status of growing plants drops below the critical level required, visual symptoms of S deficiency start appearing on the plant. The appearance of such symptoms indicates a serious condition because crop yields can decrease even without the appearance of such symptoms.

Role of sulphur in tomato plants

Sulfur is important for tomato yield. Uptake of sulfur is around 1.2lb/t of fruit. It is required throughout the season, and should be timed similar to nitrogen supplies. It maintains plant's vigorous growth..

Sulfur is a key component in the formation of several organic compounds that help give vegetables, like tomatoes, their flavor. Sulfur is essential for protein synthesis and is a component of the amino acids methionine, cysteine and cystine. Sulfur deficiency symptoms are slow to develop in the plant and often resemble symptoms of nitrogen defi- ciency. Evidence of a sulfur deficiency could include: hard and woody stems, elongated stems, and yellowish green lower leaves. Plants grown in sulfur deficient soils tend to be high in carbohydrates and nitrogen.

Symptoms of sulphur deficiency

Deficiencies are very rare in greenhouses, though can be found in crops grown in peat substrates where no sulfur fertilizer is used. Tomato plants lacking sulfur are shorter in height. The leaves are stiff and curled downward. They develop an interveinal chlorosis turning a yellowish green to yellow. Stems, veins and petioles turn purple. Necrotic spots can appear at the margins and tips of older leaves, and on the stems. Sulfur deficiency is similar in appearance to nitrogen deficiency, however it begins in the younger leaves because sulfur is not as mobile as nitrogen within the plant.

Sulphur deficiency symptoms in many ways resemble those of N - that is, the leaves become pale-yellow or light-green. Unlike N, S-deficiency symptoms appear first on the younger leaves, and persist even after N application. In cotton, tobacco and citrus, some of the older leaves are affected first.

Plants deficient in S are small and spindly with short and slender stalks, their growth is retarded, maturity in cereals is delayed, nodulation in legumes may be poor and N-fixation reduced, fruits often do not mature fully and remain light-green in color, forages contain undesirably wide N:S ratio and thus have lower nutritive value.

Treatment

It is important to soil test for sulfur and adjust levels and pH before planting a tomato crop or any crop. When S deficiency symptoms have been confirmed, soil application through a material containing readily available S such as one in the sulphate form should be applied.

Compost and gypsum are both reliable sources of sulfur. Super-phos- phate, potassium sulfate, and potassium magnesium sulfate are also options, but would require a soil test analysis to determine the major nutrients needed in addition to sulfur. In general, about 20 lbs of sulfur per acre is enough to ensure that the appropriate amount of sulfur for vegetable production. Vari- ous forms of sulfur are also used to reduce soil pH in alkaline soils.