Peppermint 465
crop in India. Depending upon nature of land and sub-soil water, a combination of
crop rotations and inter-cropping models are practised. The Maize-Lahi-Peppermint,
Maize-Potato-Peppermint, Late paddy-Peppermint, and Early paddy-Lahi-Peppermint
crop rotations have been found feasible and profitable for sub-tropical conditions.
28.3.3 Nutrient and water management
Peppermint, being a leafy crop, responds favourably to both organic and inorganic
fertilizers. Liberal manuring is essential, and the quantity and nature of the manure
has a great effect on the characteristics of the oil. Mineral salts are found to be of
much value. In the U.S.A., peppermint is given 150 kg N per ha at 60 days age
together with 50–80 kg of P 2 O 5 and potash (Guenther, 1961). Depending upon the
status of the soil fertility, a basal dose of 50–90 kg P 2 O 5 and 60–90 kg K 2 O should
be applied per ha at planting. Of the 120 kg N fertilizer, two-thirds is recommended
to be applied in early spring and one-third after the first harvest. Singh et al. (1978)
in Jammu and Bharadwaj et al. (1980) in H.P. found that peppermint crop responds
to high N levels such as 120–160 kg/ha. It was applied in three equal splits – at
planting, at 60 days age and after the first harvest.
Gupta and Gulati (1971) found that 80, 40 and 20 kg/ha of N, P and K produced
maximum herb yield in Tarai tract. Potash is particularly useful against a form of
chlorosis or ‘rust’ (Puccinia menthoe) due, apparently, to too much water in the soil,
as it often appears after moist, heavy weather in August, which causes the foliage to
drop off and leave the stems almost bare, in which circumstances the rust is liable to
attack the plants. In the south of France, sewage is extensively used, together with
Sesame seeds from which the oil has been expressed. The residues from the distillation
of the crop are invariably used as manure. Chemical fertilizers alone are equally
unsatisfactory in soils poor in organic matter, but they give excellent results in
conjunction with organic manures. Growth and terpene production of in vitro generated
M. piperita plants in response to inoculation with a leaf fungal endophyte were
characterized by Mucciarelli et al., 2003. The endophyte induced profound effects on
the growth of peppermint, which responded with taller plants bearing more expanded
leaves. The observed increase of leaf dry matter over leaf area suggested a real
improvement of peppermint metabolic and photosynthetic apparatus. A sustained
lowering of (+)-menthofuran and an increase of (+)-menthol percentage concentrations
were found in plants from both in vitro and pot cultures.
Peppermint requires frequent irrigation. It is important to keep the soil constantly
moist, although well drained. Absorption of water makes the shoots more tender, thus
facilitating cutting, and causes a large quantity of green matter to be produced.
Adequate and timely irrigation is necessary for obtaining high herb yield in drier sub-
tropical climates. The frequency of irrigation depends upon the soil texture and
weather conditions. Gupta and Gulati (1971) estimated through trials in Ta r a i region
that peppermint requires 8–10 irrigations of 2 acre inch of water per irrigation during
dry summer months till rain sets in. Randhawa et al. (1984) reported 5 cm depth of
irrigation at 60 mm of cumulative evaporation in Punjab as optimum for maximum
yield. Water logging should be avoided by ensuring adequate drainage of rain and
irrigation water.
In a study by Clark and Menary (1980), peppermint was harvested twice during
the growing season. The first harvest was conducted on 16 February 1979, and the
subsequent regrowth was harvested on 25 April 1979. High peppermint oil yields