Green light induces shade avoidance to alter plant morphology and increases biomass production in Ocimum basilicum L.

Abstract

The consequence of adding green light (505 nm) to a white light spectrum (350–700 nm) and the partial replacement of blue and red light by green light within a white light spectrum were evaluated for Ocimum basilicum L. cv. Marian regarding plant growth and development. Plants were grown in absence of far-red light consequently making green light the only light passing through the leaves. Green light (15 μmol∙m−2∙s−1) was added to a white light spectrum (108 μmol ∙m−2∙s−1) without changing the absolute intensity of the blue and red wavelengths. Adding green light to the spectrum did not affect the chlorophyll content in the leaves, nor the ratio of leaf length over leaf width. An increased biomass production, number of leaves per pot, number of leaves per stem, stem length, and individual leaf area were observed. These features are important quality attributes determining the marketable value of young basil. The partial replacement of blue and red light by green light resulted in a significant increase in biomass production compared to plants produced under a control spectrum at equal light intensity. A relative increase in green light also significantly increased stem length, leaf length and projected single leaf area. This study highlights the growth benefits of green wavelengths that are easily transmitted to the underlying leaves. We evaluated the effects of green light on basil morphology and its potential to induce shade avoidance symptoms. By observing increases in stem and leaf elongation, we have shown that green light could be used to alter the appearance and commercial value of basil.