Effects of Micro-Nutrient Deficiencies on Growth and Vitamin Content of the Tomato

Abstract

The effect of Mn, Cu, Zn, Mo, and Fe deficiencies on the ascorbic acid, riboflavin, and provitamin A content of tomato fruits was detd. The criteria of a micro-nutrient deficiency included measurements of growth and fruitfulness, the development of deficiency symptoms, and chemical analyses of both leaflets and fruits. All data were reduced and analyzed by statistical methods. An apparatus made from Pyrex glass is described for use in micro-nutrient studies in the greenhouse when it is desired to grow plants to maturity and test the effects of a number of treatments in replicated cultures. External deficiency symptoms of vegetative parts are described for plants deficient in Mn, Cu, Zn, and Fe. A characteristic Mn deficiency symptom which occurs in tomato fruits is described. A possible deficiency symptom shown by fruits with respect to zinc is also described. Deficiencies of Mn, Cu, Zn, and Fe resulted in considerably less growth and fruitfulness than was measurable in control plants. The growth and fruitfulness of plants grown with a limited supply of Mo are comparable to those of control plants. In general, chem. analyses of leaflets and fruits from plants grown with limited supplies of Mn, Fe, Zn and Mo contained significantly smaller quantities of the respective element than did the control plants. The development of the symptoms associated with a particular deficiency with respect to their position on the plant was closely correlated with the distribution of the element in the plant. The latter was detd. by chem. analyses of leaflets from the top, middle, and lower thirds of the plant. The ascorbic acid content of tomato fruits was not affected by limiting the supply of Mn, Zn, Cu, and Mo although growth and fruitfulness were seriously affected by a lack of Mn, Zn, and Cu. Fruits from Fe-deficient cultures contained 30% more ascorbic acid than did control fruits on a fresh wt. basis. The quantity of fruit produced by Fe-deficient plants, however, was significantly less than that of control plants. Slight variations in riboflavin content of tomato fruits could be correlated with the effect of micro-nutrient deficiencies. The magnitude of these variations was small and of no practical significance. The data show a pronounced effect of variations in climatic environmental conditions such as occur with different positions in the greenhouse and with a different date of fruit maturation on riboflavin content. The provitamin A content of tomato fruits was not significantly affected by a limited supply of the micro-nutrients considered in this expt. No significant effect of environmental factors was obtained with respect to this vitamin.