Optimum range in leaves of potato grown under plastic mulches. V. Physiological indices and ionic balance

An experiment, conducted for three years with Solanum tuberosum L. var. Spu nta, consisted of covering the soil surface with different plastic polyethy lene [PE] sheets: transparent PE(25 mu thick, T1), white PE (25 mu, T2); co extruded black and white PE (50 mu, T3); black PE (25 mu, T4); no plastic c over (control, T0). In this research we determined optimum ranges of: (1) i onic balance and related parameters and ratios; (2) quality indices (pH, as corbic and citric acids); (3) physiological indices (alkaline index, Fe Ind ex and vegetative index) and (4) physiological ternary groups of soluble an d total macro and micronutrients.