Apot experiment was conducted to study the effect of soil-N
fertilization rates (2 and 4 g of ammonium nitrate/plant) and foliar
spray with Zn and Mn at 2 concentrations (100 and 150 ppm for each)
on the vegetative growth, flowering and chemical composition of
amaryllus (Hippeastrum vittatum, herb) plants. The obtained data
showed that, fertilizing amaryllus plants with 4 g ammonium
nitrate/plant significantly increased the vegetative growth characters
i.e., plant height, number of leaves/plant, leaves area, fresh and dry
weights of leaves, bulbs and the whole plant. Moreover, increased
number of bulbs and bulblets/plant, bulb size and bulb dry weight.
Flowering traits such as length of floral stalk, number of flowers on
floral stalk, average dry weight of floral stalk and vase life of flowers
were increased as well. The same rate (4 g) of N-fertilization also led
to the increase in the concentration of chlorophylls (a and b),
carotenoids, total carbohydrates, anthocyanin in flowers at picking
time and five days later, and leaves content of N and P. The 2 g
ammonium nitrate application/plant significantly increased both K and
Zn contents in plant leaves. On the other side, leaf content of Mn and
Fe was not affected with the 2 or 4 g ammonium nitrate rate. Foliar
spray with the mixture of Zn and Mn at the rate 150 ppm of each
significantly increased all the above mentioned vegetative growth
characters and flowering traits. The tested treatments also caused
insignificant increase in the leaves content of chlorophylls (a and b),
carotenoids, total carbohydrates, flowers content of anthocyanin at
picking time and 5 days later, and accumulation of N and K. The
greatest accumulation of P occured when plants were sprayed with Mn
at 150 ppm. On the contrary, the highest value of Fe was observed in
plants sprayed with Zn and Mn at the concentrations of 150 and 100
ppm, respectively. Regarding the combined effect of soil N application
and foliar spray with (Zn+Mn), the results revealed that, fertilizing the
amaryllus plants with 4 g ammonium nitrate and foliar application with
mixture of Zn and Mn at 150 ppm concentration for each significantly
increased all vegetative growth characters, floral parameters, leaves
content of chlorophylls (a and b), carotenoids, total carbohydrates, N, P
and flowers content of anthocyanin at the time of picking or five days
later. The greatest plant content of K was found when a plant recivied
2 g of N and sprayed with Zn and Mn at 150 ppm for each. Providing
amaryllus plants with 2 g of ammonium nitrate and foliar spraying with
only Zn at 150 ppm resulted in the greatest leaf content of Zn and Fe.