It was noted that the oil
content in the fresh herbage decreased with the use of
organic mulching and an increase in rates of N (Fig. 1),
but the magnitude of increase in the herb yield was
higher than the decrease in the oil content, hence the oil
yield was also significantly higher. Higher doses of N are
known to increase the size of the cells and cause succulency
in plants; this might be the reason for the
elongation of oil glands and the dilution of oil concentration
in the leaves observed. Ram and Kumar (1998b)
observed the reduction in oil content of menthol mint
leaves with increased rates of N application.