EFFECT OF TRYPTOPHAN, Fe, Zn AND Mn FOLIAR APPLICATION ON GROWTH, PRODUCTIVITY AND CHEMICAL COMPOSITION OF ROSELLE PLANTS

Two-field trials were conducted at the Experimental Farm of the
Hort. Dept., Faculty of Agric., Moshtohor Benha Univ during 2006
and 2007 seasons. Experiments aimed to study the effect of foliar
spray with tryptophan at 0.0, 50, 100 and 150 ppm. and foliar nutrition
with Fe, Zn and Mn each at rates of 150 ppm. plus the control on
growth, yield and chemical constituents of roselle plants. Plants were
sprayed with tryptophan, Fe, Zn and Mn three times started at 45 days
after planting and at three weeks intervals. Experimental design was
split plot; tryptophan arranged in the main plots and micronutrients
were arranged in sub plots. Results showed that, foliar spray with
tryptophan supplemented with Fe, Zn and Mn treatments enhanced
most growth and productivity parameters, such as plant height,
number of branches, fresh and dry weights of branches/plant, number
of leaves, fresh and dry weights of leaves/plant and also, increased
each of fruits number, fresh weight of fruits /plant, fresh and dry
weights of sepals /plant as compared with control in both seasons.
Moreover, total carbohydrates % and sepals acidity, N%, P%, K%,
anthocyanin and vitamin-C content were increased by spraying roselle
plants with all concentrations of the used treatments.
Generally, tryptophan foliar application at rates 50, 100 and 150
ppm. increased all growth and yield parameters especially the high
rate (150 ppm.) compared with control in both seasons. Furthermore,
Fe, Zn and Mn foliar nutrition at 150 ppm. of each increased the plant
height, number of branches, fresh and dry weights of branches/plant,
number of leaves, fresh and dry weights of leaves/plant and also,
EFFECT OF TRYPTOPHAN, Fe, Zn AND Mn FOLIAR772
increased number of fruits/plant, fresh weight of fruits/plant, fresh and
dry weights of sepals/plant., total carbohydrates% and sepals acidity,
N%. P%, K%, anthocyanin and vitamin-C content as compared with
control plants. The most favorable growth, yield and the highest
chemical content were obtained when plants sprayed with the three
micronutrients (Fe+ Zn+Mn) each at 150 ppm. in both seasons.
Furthermore, the combinations resulted from the interaction
between spraying tryptophan at rates (50, 100 and 150 ppm.) and
foliar nutrition of Fe, Zn and Mn at 150 ppm. for each increased plant
height, number of branches, fresh and dry weights of branches/plant,
number of leaves, fresh and dry weights of leaves/plant and also
increased fruit's number/plant, fresh weight of fruits/plant, fresh and
dry weights of sepals/plant., total carbohydrates% and sepals acidity,
N%. P%, K%, anthocyanin and vitamin-C content compared with
control plants in the first and second seasons.
Consequently, it can be safely spray Hibiscus sabdariffa plants
with tryptophan at 150 ppm. supplemented with foliar nutrition with
(Fe+Zn+Mn) each at 150 ppm. to enhance the most growth, yield and
chemical constituents of roselle (Hibiscus sabdariffa, L.) plants.