The Use of UV Radiation to Control the Architecture of Salvia splendens Plants. I. Effects on Plant Growth, Water Relations and Gas Exchange

Abstract

In experiments with Salvia splendens plants grown in the greenhouse we evaluated the possible use of irradiation with unfiltered UV (UVA + UVB + UVC) lamps for the control of plant growth. The effect of UV irradiation on the growth of S. splendens plants in the greenhouse was closely dependent on the growing season and the level of available photosynthetically active radiation. In summer UV treatments were ineffective, but in the low light conditions of winter UV irradiation inhibited the growth via both photomorphogenic and photosynthetic effects. The reduction of stomata1 conductance and expansion growth, which in turn depressed photosynthesis and dry matter accumulation, were not a consequence of an impairment of plant water status but appeared to be a direct UV effect on stomata and cell wall rheological properties. Our findings suggest that the use of unfiltered UV irradiation could become an effective tool for the regulation of growth in greenhouse crops, particularly during the poor light conditions of the winter season.

Effects of PAR and UV‐B Radiation on Herbal Yield, Bioactive Compounds and Their Antioxidant Capacity of Some Medicinal Plants Under Controlled Environmental Conditions

“…PAR (400-700 nm) was from Philips 400 W high pressure sodium-vapor lamps (Son-T Agro). Young plants received plant-weighted UV-B radiation in duration of 1 week (12)(13)(14)(15)(16)(17)(18)(19) and after that, up to the end of experiment, only additional photosynthetically active radiation (except of control treatment). Plants were placed 50 cm below the UV-B lamps and 60 cm (INT treatment), 53 cm (FGC treatment), 50 cm (PAR treatment) below the PAR lamps, with 0.0693 W m À2 UV-B (UV-B lamps) and 306 lmol m À ² s (INT treatment), 360 lmol m À ² s (FGC treatment), 414 lmol m À ² s (PAR treatment) photosynthetically active radiation (PAR lamps).…”

“…Effects of PAR and UV-B radiation on herbs and other plant species were already reported by some authors (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). UV-B can also essentially influence the growth of herbs (15). Controlled cultivation of herbs in hydroponics systems provides excellent conditions for metabolic plant profiling to produce selected and desired compounds due to the effect of main exogenic factors, promising new industrial opportunities (16)(17)(18)(19).…”

Ultraviolet‐B radiation effects on plants: induction of morphogenic responses

“…Rather, UV‐B induced morphogenic responses may be exploited in agricultural systems to improve the architectural properties of crop species. Giannini et al. (1996) showed that broad band UV can be used to obtain glasshouse‐grown Salvia splendens plants with a more compact habit and a potentially greater ability to withstand handling and transport.…”

Ultraviolet‐B radiation induces complex alterations in stomatal behaviour

“…Unlike mesophyll tissue, the upper epidermal leaf surface is exposed to relatively high fluences of UV‐B radiation ( Ålenius et al 1995). Effects of UV‐B on the epidermal layer include the inhibition of cell expansion, leaf bronzing and curling ( Teramura and Ziska 1996; Greenberg et al 1996), and alterations in stomatal aperture and/or stomatal conductance ( Grammatikopoulos et al 1994; Day and Vogelmann 1995; Giannini et al 1996; Zeuthen et al 1997; Nogués et al 1998).…”