Some effects of enhanced UV-B irradiation on the growth and composition of plants

Abstract

Barley (Hordeum vulgare), corn (Zea mays), bean (Phaseolus vulgaris), and radish (Raphanus sativus) seedlings were continuously irradiated under a lighting device for 5-10 d at an increased ultraviolet (UV)-B fluence rate. In their growth parameters, composition, and leaf surface, these four species responded differently to the increased UV-B exposure. Bean seedlings suffered the most serious effects, radish and barley less, and corn was hardly influenced at all. In all plant species, the fresh weight, the leaf area, the amounts of chlorophylls, carotenoids and the galactolipids of the chloroplasts were reduced. The lipid content of the corn and bean seedlings also diminished. But all the irradiated plants showed a rise in their protein content compared to the control plants. The content of flavonoids increased in barley and radish seedlings by about 50%. The effects on growth parameters and composition were more extensive with increasing UV-B fluence rates, at least as shown in the case of barley seedlings. The fresh weights fell proportionally with the chlorophylls and carotenoids. In contrast, the flavonoid content of barley leaves rose parallel to the increasing UV-B fluence rates and reached 180% of the value in the control plants with the highest UV-B fluence rate. Scorching appeared regularly in the form of bronze leaf discoloration at the highest UV-B fluence rates. Scanning electron micrographs of the leaf surface of UV-B irradiated plants showed deformed epidermal structures.

Effects of 24-epibrassinolide Pre-treatment on UV-B-Induced Changes in the Pigment Content of Pea Leaves

“…Chl b is more affected by UV-B radiation than Chl a, which results in an increase of the ratio Chl a/b. These observations are in agreement with previously reported data about the effect of UV-B on pigments [ 7,9 ], indicating a preferential destruction of Chl b biosynthesis and/or degradation of precursors upon UV-B exposure. Comparison between the control and EBR-treated plants, subjected to UV-B irradiation, indicates that exogenous application of EBR has a protective effect against UV-B-induced pigment destruction, Chl b being more protected by EBR than Chl a, thus leading to a decrease of Chl a/b ratio (Table 1).…”

“…The content of chlorophylls, carotenoids and UV-B absorbing compounds is frequently used as indicator of plant sensitivity to UV-B radiation ([ 8 ] and refs therein). It has also been demonstrated that the UV-induced effects on photosynthesis and pigment content depend on the radiation doses and duration of treatment [ 8,9 ].…”

Effects of u.v.‐B radiation on epicuticular wax production and chemical composition of four Picea species

“…General symptoms of increased u.v.-B exposure include reductions in plant height (Sullivan & Teramura, 1988 ;Barnes, Flint & Caldwell, 1990) and biomass production (Tevini, Iwanzik & Thoma, 1981 ;Naidu et al 1993). There is large variation in plant response to u.v.-B between and within species.…”

Impact of enhanced ultraviolet-B irradiance on cotton growth, development, yield, and qualities under field conditions

“…One-third to one-half of all plant species tested are deleteriously affected by UV-B levels "above ambient" (Sullivan, 1992). A substantial number of studies have been conducted that have evaluated the potential consequences of an increase in UV-B radiation on many plants (Tevini et al, 1981;Teramura et al, 1990;Miller et al, 1994;Caldwell et al, 1998;Correia et al, 1998Correia et al, , 1999Li et al, 2000, Searles et al, 2001), but we have a rather limited understanding of the role that UV-B radiation plays in controlling cotton growth, development, yield and quality. Searles et al (2001) searched for "all suitable published studies" with field-based measurements of UV-B influences on vascular plants and found no studies on cotton.…”