Light quality (sunlight spectrum) management promises to provide a new technological alternative to sustainable production
in horticultural crops. However, little information exists about physiological and technological aspects on light quality
management in fruit crops. Sunlight composition changes widely in orchard canopies, inducing different plant responses in
fruit trees mediated by phytochrome (PHY) and cryptochrome (CRY) activity. High proportion of far-red (FR) in relation
to red (R) light increases shoot elongation, while blue (B) light induces shoot dwarfing. Red and ultraviolet (UV) light
increases fruit skin anthocyanin synthesis, while FR light shows a negative effect. Red and B light can also alter leaf
morpho-physiological traits in fruit trees, such palisade thickness, stomatal aperture, and chlorophyll content. Besides
improvement of photosynthetically active radiation (PAR) availability, the use of reflective films improves UV and R
light proportion, with positive effects on PHY mediated-responses (fruit color, fruit weight, shoot growth), as reported in
apple (
Malus domestica
Borkh.), peach (
Prunus persica
[L.] Batsch), and sweet cherry (
Prunus avium
[L.] L.). Colored
nets widely alter spectral light composition with effects on plant growth, yield, and quality in apple, kiwifruit (
Actinidia
deliciosa
[A. Chev.] C.F. Liang & A.R. Ferguson), peach, and blueberry (
Vaccinium corymbosum
L.) orchards. Mechanisms
of colored nets seem to be associated to photosynthetic and morphogenetic process regulated by PAR availability, R/B light
proportion, and CRY activity. Alteration of light quality affects significantly fruit tree plant responses and could be a useful
tool for sustainable (e.g. lower use of chemicals and labor-practices) management of yield and quality in modern orchards.
