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Factors Affecting Calcium Nutrition of Celery, Tomato, and Pepper¹

ABSTRACT

All of the factors most frequently associated with the prevalence and severity of blackheart of celery and blossom-end rot of tomatoes and peppers can be placed into two categories according to the mechanisms by which they affect calcium nutrition.

Mechanism A.—Excessive soluble ammonium, potassium, magnesium, or sodium or a deficiency of soluble calcium (low calcium ratio) cause a decreased calcium uptake and increased incidence of the physiological disorders. On an equivalent basis, ammonium decreases calcium uptake of tomatoes to the greatest degree; sodium the least.

Mechanism B.—Excess total salts can cause a calcium deficiency and has frequently been associated with the prevalence of these disorders even when the measurable calcium ratio is considered high or adequate.

A deficiency of boron was of minor importance in affecting the calcium nutrition, but high calcium ratios severely accentuated a boron deficiency.

A favorable calcium ratio should be maintained to the best degree possible by (1) supplying larger amounts of soluble calcium salts, and (2) avoiding, as much as possible, excesses of soluble ammonium, potassium, magnesium, or sodium salts as well as excess total soluble salts.

Periodic calcium sprays are recommended as a source of calcium supplementary to that supplied by the soil as a means of maintaining an adequate supply of calcium to meet the plant requirement at all times.

¹ Florida Agr. Exp. Sta. Journal Series, No. 572. Presented before Div. IV, Soil Science Society of America, Nov. 1956 at Cincinnati, Ohio.

² Assoc. Soils Chemist, Gulf Coast Exp. Sta., Bradenton, Florida.

Received for publication December 6, 1956. Accepted for publication May 14, 1957.