This work was conducted on 6-month-old potted mango seedlings Hindi Bi-Sinera (cv.) to investigate effect of nitrogen and /or manganase soil applied rates on plant growth, nutritional and physiological status of mango plants. In this experiment, four rates of N ( 0.0 , 50 , 100 and 200 ppm N ) in the form of ( NH4)2 So4 and four rates of Mn ( 0.0 , 5 , 10 and 20 ppm Mn ) in the form of MnSo4 and their combinations were soil applied.
Soil application of N and / or Mn to mango seedlings considerably and significantly stimulated plant growth causing a great increase in plant height, stem thickness, leaves number / plant, leaf area, assimilation area and dry matter accumulation. These growth parameters were positively related to the rate of N or Mn fertilizers. Moreover, combination treatments, particularly 200 ppm N × 20 ppm Mn, were more effective than single treatments in this concern.
Leaf content of chlorophyll (a & b) was markedly increased by supplying mango seedlings with N and / or Mn and this increase was related to the rate of both nutrients, but the beneficial effect of N was more than that of Mn. In addition, combinations of them seemed to be more effective than single treatments of N or Mn. Total carbohydrates in mango stem as affected by N and / or Mn followed the same trend of leaf chlorophyll content which was closely related to these pigments.
Supplying mango seedlings with N and / or Mn fertilizers, in particular at 200 ppm N or 20 ppm Mn, markedly and significantly encouraged N, P and Mn uptake which increased its levels in different plant organs. Potassium content in leaves, stem and roots of mango seedlings was gradually decreased by increasing application rate of N up to 200 ppm. The reverse trend could be observed with Mn supplying where K levels in plant organs were gradually increased as the rate of Mn raised up to 20 ppm.