INFLUENCE OF SOIL APPLICATION OF IODINE AND SUCROSE ON MINERAL COMPOSITION OF SPINACH PLANTS

Iodine is not an essential nutrient for plants. Side-effects of its application on mineral nutrition of plants have not yet been thoroughly documented. The aim of the study was to evaluate the influence of soil application of iodine and sucrose on mineral composition of spinach plants. In 2009-2010, a pot experiment with spinach Spinacia oleracea L. 'Olbrzym zimowy' cv. cultivation on mineral soil was carried out in the plastic tunnel. The research included diverse combinations with pre-sowing iodine fertilization (in the form of KI) and soil application of sucrose: 1) - control (without iodine fertilization and sucrose application), 2) - 1 mg I dm(-3) of soil, 3) 2 mg I dm(-3) of soil, 4) 1 mg I + I g sucrose dm-3 of soil and 5) 2 mg I + I g sucrose dm(-3) of soil. In spinach samples as well as soil after cultivation the content of: P, K, Mg, Ca, S, Na, B, Cu, Fe, Mn, Mo, Zn, Al, Ba, Cd, Ce, Co, Cr and La was determined using ICP-OES technique, while Cl using nephelometric method. Iodine synergistically improved the uptake of Mg, Na and Ce as well as Fe (for Fe only in the case of higher iodine doses) while antagonistically affected Cr uptake by spinach plants. After application of iodine in a dose of 2 mg I dm(-3) soil, higher accumulation of Na, Fe, Zn and Al was observed along with reduced concentration of P, S, Cu and Ba in spinach plants when compared to the control. Simultaneous application of iodine and sucrose (in comparison to the control or plants fertilized, only with iodine) contributed to a significant increase in the accumulation of K, S and Mo as well decreased content of Mg, Fe, Ba, Co and La in spinach plants.