Effects of light intensity and amount of supplemental LED lighting on photosynthesis and fruit growth of tomato plants under artificial conditions

Abstract

We assessed the effects of light intensity (photosynthetic photon flux [PPF in µmol·m -2 ·s -1 ]) and number of irradiated leaves on photosynthesis and the fruit growth of individual tomato plants to develop supplemental LED lighting techniques for greenhouse tomato production. In Experiment (Exp.) 1, three PPF levels (P200, P500, and P1000) were applied to a post-anthesis tomato plant for three weeks, each plant pruned to have one leaf and one truss with three flowers. The fruit set and leaf and fruit dry-weight increased with increasing PPF; however, after P500 and P1000 treatments, the leaves showed signs of stress and accompanying disorders. Thus, to increase the fruit set ratio and growth rate of tomato fruits and plants, the total amount of irradiation received by each plant should be increased by increasing the number of irradiated leaves, rather than raising the PPF per leaf. For prolonged cultivation, P200 was the optimal PPF per leaf under the tested treatments. Exp. 2 used standard tomato plants with no leaves or trusses removed. We used an assimilation chamber to examine the effect of the number of leaves receiving P200 irradiation on the photosynthetic rate (Pn) per plant (above ground part). The Pn per plant in treatments where one and two leaves were irradiated by supplemental LED lighting were, respectively, 12 and 28％ higher than that in the control (only top lighting). Therefore, fruit growth and yields in tomato cultivation may be raised via acceleration of photosynthesis by increasing the number of leaves that receive P200 irradiation rather than by increasing PPF.

Interaction of Supplementary Light and CO2 Enrichment Improves Growth, Photosynthesis, Yield, and Quality of Tomato in Autumn through Spring Greenhouse Production

“…Previous studies in this area are few (Fierro et al, 1994;Hikosaka et al, 2013;Nilsen et al, 1983). Here we investigate the effects of CO 2 enrichment and supplementary light on photosynthesis, growth, yield, and quality of tomatoes.…”

“…Previous research has focused largely on the effects of individual factors of supplementary light or supplementary CO 2 on plant growth, yield, and quality (Hikosaka et al, 2013;Mamatha et al, 2014;Yelle et al, 1990;Zou et al, 2016). Urban et al (2014) reported that the enhancement of photosynthesis under CO 2 enrichment is strongly affected by light intensity.…”

Effect of irradiating the leaf abaxial surface with supplemental light-emitting diode lights on grape photosynthesis

“…Moreover, LED light sources within a narrow band of the spectrum (light quality) can match to preferred wavelengths of the plant photoreceptors to regulate plant development and physiology (Singh et al ). Supplemental red plus green LED light for strawberries increased the leaf dry mass, fruit yield and soluble solids by 2.0, 2.4 and 1.1 times, respectively, compared with that of the control (Hidaka et al , Hikosaka et al ). Red or blue LED light‐supplementation can affect abscisic acid metabolism and anthocyanin synthesis in grape skin by regulating the expression of secondary metabolism‐related genes (Kondo et al ).…”

Effects of Supplemental Lighting on Growth and Medicinal Compounds of Japanese Honeysuckle (<I>Lonicera japonica</I> Thunb.)

“…Generally, plants can be classified as either annual, biennial, or perennial. The Pn in tomato plants, which is an annual plant, ranges from 15 to 20 mol CO2 m 2 s 1 at light saturation point with or without SL (Hikosaka et al, 2013). In contrast, the Pn in perennial woody plants is about 4 to 8 mol CO2 m 2 s 1 at light saturation point (Reich et al, 1998).…”