Changes of Nutrient Contents in Tomato Fruits Under The Influence of Increasing Intensity of Manganese Nutrition

The aim of conducted in years 2008-2012 studies was to assess the efficiency of application of increasing manganese levels on the nutritive value of tomato fruits (Lycopersicon esculentum Mill. cvs. ‘Alboney F1’ and ‘Emotion F₁’), expressed in the contents of macro- and micronutrients. Plants were grown in rockwool with application of nutrient solution characterized the following chemical composition (in [mg dm–³]): N-NH₄ 2.2, N-NO₃ - 230, P - 50, K - 430, Ca - 145, Mg - 65, Cl - 35, S-SO₄ - 120, Fe - 2.48, Zn - 0.50, Cu - 0.07, pH -5.50, EC - 3.00 mS cm–¹. The following manganese plant nutrition levels were examined (in mg Mn · dm–³): 0.06 (control), 0.3, 0.6, 1.2 (Experiment I), 2.4, 4.8, 9.6 and 19.2 (Experiment II); (denoted as Mn-0, Mn-0.3, Mn-0.6, Mn-1.2, Mn-2.4, Mn-4.8, Mn-9.6; Mn-19.2). The source of manganese was manganese sulfate (MnSO₄ · H₂O, 32.3% Mn). The nutritive value of tomato fruits changed significantly under the influence of the application of wide range of manganese concentrations. It was found a significant reduction of the content of phosphorus (Exp. I, II), potassium (Exp. II), calcium (Exp. I, II) and magnesium (Exp. I, II). Manganese influence on the decreasing content of other metallic micronutrients (Fe, Zn, Cu) in fruits. Cultivar had a significantly influence on the content of: nitrogen (except Mn-2.4, Mn-4.8, Mn-9.6), potassium (in Exp. II, except Mn-4.8), calcium (except for Mn-0.6, Mn-2.4), magnesium (except Mn-0.3 and Mn-2.4), iron (except Mn-1.2), manganese and zinc (except control combination) and copper (except Mn-0.6 and Mn-1.2). The highest contents of N, Ca and Mg in fruits were recorded for the application of Mn-0, while for P and K - at 0.3 mg Mn dm–³, whereas it was lowest for all these nutrients (except N) in the case of Mn-19.2 (Exp. II). The reduction of nutrient contents amounted to (% changes: from the lowest content to the highest content): N (11.3), P (48.1), K (24.8), Ca (75.4), Mg (57.5), Fe (59.2), Zn (65.4) and Cu (43.7).