This study was conducted during two successive seasons of
2003/2004 and 2004/2005 at the Experimental Farm of Ornamental
Horticulture Department, Faculty of Agriculture, Cairo University to study
the effect of zinc at (0, 50 and 100 ppm) and some amino acids, tryptophan
at (0, 50 and 100 ppm) and methionine at (0, 25 and 50 ppm) on growth,
yield, oil production and chemical composition of caraway (Carum carvi,
L.) plants. The results showed that zinc application had no significant effect
on plant height in the first season, number of branches / plant, dry weight /
plant and number of umbels / plant in both seasons. Whereas zinc at 50 ppm
significantly increased plant height and dry weight / plant in the second
season. Zinc at 50 and 100 ppm significantly increased fresh weight / plant
in both two seasons , fruit yield / plant and oil yield/ plant in the second one.
Zinc at 50 and 100 ppm insignificantly increased oil percentage in both two
seasons. Zinc at 50 and 100 ppm decreased limonine percentage in the oil
and increased carvone percentage in the oil in both two seasons, total
carbohydrates contents in both leaves and roots in the first season. Zinc at
50 ppm increased total carbohydrates in fruits in the first season, while 100
ppm increased it in leaves, fruits and roots in the second one.
Tryptophan and methionine had a significant effect on plant fresh
and dry weights in both seasons. The most effective treatment was
methionine application at 50 ppm. Tryptophan and methionine at 50 ppm
gave the highest fruit yield / plant in the first and second seasons,
respectively. Amino acids (tryptophan and methionine) insignificantly
increased volatile oil percentage and oil yield / plant in the first season.
Whereas, methionine at 25 ppm significantly decreased oil percentage in the
second season. Methionine at the highest rate (50 ppm) decreased limonene
and increased carvone percentages in caraway essential oil in both seasons.
Amino acids application increased total carbohydrates percentage in leaves
in the first season, in fruits and roots in both two seasons.
Interaction between zinc and amino acids (tryptophan and
methionine) had a significant effect on most vegetative growth
characteristics, fruit yield / plant, oil percentage and oil yield / plant, and
increased limonine and carvone contents in the oil and total carbohydrates
percentage in different plant organs.