PHYSIOLOGICAL AND BIOCHEMICAL-CHANGES IN YOUNG MAIZE PLANTS UNDER IRON-DEFICIENCY .1. GROWTH AND PHOTOSYNTHESIS

Young maize plants, grown hydroponically, were supplied with different amounts (7.5, 0.75, 0.15, 0.075, and 0 mg Fe/L) of iron (Fe). At 14, 21, and 28 days, parameters characterizing growth and photosynthesis w ere determined. Iron-deficiency resulted in significant changes in bio mass accumulation and distribution between vegetative organs as well a s changes in the content of chlorophyll a, chlorophyll b, and the caro tenoids. The photosynthetic rate per leaf area was decreased. Part of C-14 incorporated in low molecular compounds was increased and the sha re of amino acids and organic acids in them was increased. Plants supp lied with 1/10th of the optimum Fe required partially adapted to the F e deficiency. Plants with visual symptoms of Fe deficiency showed some peculiarities as compared to those plants severely Fe-deficient.