02414nam a2200253 a 450000100080000000500110000800800410001910000170006024500660007726000460014330000090018952018000019865000140199865000110201265000200202365000130204365000100205665000200206665000140208665000120210065000230211265300110213565300140214615600062000-06-19       1979    bl uuuu  m   00u1 u    #d1 aPAVAN, M. A.  aManganese and nickel toxicity in coffee (Coffea arabica, L.).  aRiverside: University of Californiac1979  a55p.  aSand cultures with different amounts of Mn and Ni alone and in combination were used to characterize toxicities of Mn and Ni with coffee plants. The third pair of leaves was found to reflect closest the mineral nutrition status of the plant. Manganese and Ni uptake were proportional to the supply and plant injury was proportional to Mn and Ni uptake. Nickel toxicity: growth decrease upon adding Ni to the solution culture at rates of 0.0, 0.5 and 1.0 mg/g. The reduced growth was associated with leaf Ni values of 30 to 75 ug/g. Excess Ni in solution also increased the the concentration of Mn and Fe in the leaf while leaf chlorophyll decreased.  Symptoms of Ni toxicity were chlorosis and necrotic spots on younger leaves. Manganese toxicity: plant growth and dry weight were at a maximum for solution culture levels of 2.5 and 5.0 mg Mn/1 which were associated with leaf Mn over a range of 600 to 1,200 ug/g. Leaf Mn values for coffee seedlings growing in nutrient solution containing 20 mg Mn/1 ranged from 2,500 to 2,800 ug Mn/g and were associated with a 30% reduction in growth. Yields were at a maximum when the Mn/Fe ratio in leaf tissue was 7.64 and decreased to 30% of the maximum as this ratio was increased to 18. Excess of Mn in solution decreased the concentration of Fe and Ca in leaf tissue. Total leaf chlorophyll increased at a maximum when the leaf Mn was at 600 ug/g and decreased as leaf a Mn increased. Leaf Mn concentrations of 1,200 and 2,600 ug/g were associated with medium and very severe leaf toxicity. Symptoms of Mn toxicity were marginal chlorosis and few necrotic spots on younger leaves. The combination of Mn and Ni produced in addition to the symptoms described, small internodes, streak necrosis of the leaf, petiole, and branch, defoliation, and dieback.  amanganese  anickel  aplant nutrition  atoxicity  aCafé  aCoffea Arábica  aManganês  aNíquel  aNutrição Vegetal  aCoffee  aToxicidez