Difference between Nighttime and Daytime UV-B Irradiation with Respect to the Extent of Damage to Perilla Leaves

Abstract

Although ultraviolet-B (UV-B) light (280-315 nm) irradiation effectively controls spider mites in horticultural crop production, it also causes plant damage, leading to growth suppression, changes in morphology, and leaf scorching. However, sensitivity to UV-B varies among plant species. Here, we assessed the effect of UV-B on growing perilla (Perilla frutescens var. crispa) plants. Three experiments were conducted. In the first experiment, plants of the variety 'Akachirimenshiso' were grown in a plastic house with natural light conditions and subjected to three treatments: natural UV (control), −UV, and natural UV plus artificial UV-B treatment (50 mW·m

Effects of Nocturnal UV-B Irradiation on Growth, Flowering, and Phytochemical Concentration in Leaves of Greenhouse-Grown Red Perilla

“…As UV-B light sources are being used as artificial lighting to improve phytochemical concentration and to control flowering, it is desirable to provide illumination to an extent that does not impair growth rate and phenotype quality. Using the same light source as that used in the present study, Ota et al [ 21 ] did not report any effect on plant growth under conditions of exposure to 3 h of illumination at 0.05 W m −2 (0.54 kJ m −2 day −1 ). In the present study, no growth inhibition via subjection to UV-B irradiation was observed under the same conditions.…”

“…It has been reported that UV-B irradiation decreases the concentration of anthocyanins in red perilla leaves and causes a change in their color to green [ 10 , 21 , 24 ]. In this study, we observed leaf greening due to UV-B irradiation.…”

“…Recently, research has been conducted to control spider mites in greenhouse perilla cultivation using UV-B fluorescent lamps [ 21 , 22 ]. Furthermore, the technique of pest control using UV-B fluorescent lamps has been developed to control the occurrence of powdery mildew in strawberries [ 23 ]; moreover, a UV-B fluorescent lamp for pest control has been introduced which is now commercialized as an integrated pest management (IPM) technology for strawberry cultivation in Japan.…”

“…However, the use of UV-B fluorescent lamps to improve the phytochemical concentration in greenhouse cultivated perilla has not been studied, and its effect on flowering remains unknown. Furthermore, UV-B radiation reportedly exerts negative effects, such as changes in leaf color [ 21 ] and reduced growth [ 10 ]; therefore, it is necessary to establish irradiation conditions that do not cause a reduction in phenotypic quality and productivity.…”

The sensitivity of sunflower (Helianthus annuus L.) plants to UV-B radiation is altered by nitrogen status

“…The inconsistent findings may be explained by the fact that plant species have different sensitivity to UV-B radiation in addition to the adverse growth conditions among the different studies such as the ratio of PAR to UV-B radiation during the growth period. The UV-B radiation damage to plants can be reduced by combining UV-B irradiation with visible light (OTA et al, 2017). In Table 1 -Interactive effects of nitrogen and UV-B radiation on shoot, stem and leaves dry matter (g), stomatal conductance (gs, mol m -2 s -1 ), photosynthesis (A, μmol m -2 s -1 ), transpiration (E, mmol m -2 s -1 ), intercellular CO2 concentration (Ci, μmol mol -1 ), total chlorophyll and carotenoid content (mg g -1 FW) activity of peroxidase (PG-POD, μmol min -1 mg -1 protein) and malondialdeyde content (MDA, nmol g -1 fresh weight) of sunflower plants.…”