The modulation of light is of importance during cultivation
of medicinal plants to obtain desirable morphological
and physiological changes associated with the maximum
production of active principles. This study aimed to evaluate
the effect of the light spectrum transmitted by colored shade
nets on growth, essential oil production and photosynthetic
behavior in plants of lemon balm (
Melissa officinalis
L.)
Plants were cultivated in pots for 4-mo under black, red,
and blue nets with 50% shading, and full sunlight exposure.
Biometric and anatomical variables, essential oil yield,
global solar radiation, photon flux density, chlorophyll
content, and gas exchange parameters were measured
in
M. officinalis leaves. The results showed that despite
being considered a partial shade plant, this species is able
to adapt to full sunlight conditions without increasing
biomass production. The spectral changes provided by
colored shade nets did not caused any noticeable change
in leaf anatomy of
M. officinalis. However, the use of blue
net resulted in increments of 116% in plant height, 168% in
leaf area, 42% in chlorophyll content and 30% in yield of
essential oil in lemon balm plants. These plant’s qualities
make the use of blue net a cultivation practice suitable for
commercial use.
