Jh. Loughrin et Mj. Kasperbauer, Light reflected from colored mulches affects aroma and phenol content of sweet basil (Ocimum basilicum L.) leaves, J AGR FOOD, 49(3), 2001, pp. 1331-1335
Basil (Ocimum basilicum L.) is an herb the leaves of which are used to add
a distinct aroma and flavor to food. It was hypothesized that the size and
chemical composition of sun-grown basil leaves could be influenced by the c
olor of light reflected from the soil surface and by the action of the refl
ected light through the natural growth regulatory system within the growing
plants. Leaf morphology, aroma compounds, and soluble phenolics were compa
red in basil that had been grown over six colors of polyethylene row covers
. Altering the ratios of blue, red, and far-red light reflected to growing
plants influenced both leaf morphology and chemistry. Leaves developing ove
r red surfaces had greater area, moisture percentage (succulence), and fres
h weight than those developing over black surfaces. Basil grown over yellow
and green surfaces produced significantly higher concentrations of aroma c
ompounds than did basil grown over white and blue covers. Leaves grown over
yellow and green mulches also contained significantly higher concentration
s of phenolics than those grown over the other colors. Clearly, the wavelen
gths (color) of light reflected to growing basil plants affected leaf size,
aroma, and concentrations of soluble phenolics, some of which are antioxid
ants.