EFFECT OF ZINC SUPPLEMETATION ON GROWTH, BIOCHEMICAL PROCESS AND YIELD IN ZEA MAYS

This paper aims the effect of zinc at different concentrations on development of Zea mays and the characteristic reactions generated or inhibited by the zinc. The plants were raised in well-established conditions, and Zn was administered at variable levels ranging from acute deficiency (sample 0, witness) to excess (100 mg/kg, 300 mg/kg and 700 mg/kg). Zinc is an essential micronutrient required by plants for normal growth and development. This metal was determined by Flame Atomic Absorption Spectrometry (FAAS). At lower amount or even absence of zinc, symptoms of Zn deficiency were depression in growth, chlorosis and necrosis of mature leaves, along with development of purple pigmentation at leaf margins. Zinc at less and more than 100 mg/kg reduced vegetative yield, seed weight, concentration of chlorophyll (a and b), sugars, and protein and elevated the concentration of phenols and activity of different enzymes in metabolism processes. In addition to various changes in metabolism of Zea mays, Zn at higher levels induced symptoms of toxicity on leaves as necrosis, and reduction in growth and leaf size. Phosphorus content in leaves decreased concomitantly with an increase in Zn supply from 100 mg/kg to 700 mg/kg. The toxicity of higher amount of zinc added of plant is expected to be in the last samples Zn3 as well when the yield of growth is less according with the data from literature.