Response of 19 cultivars of soybeans to ultraviolet‐B irradiance

Abstract

Nineteen soybean cultivars were grown for four weeks in controlled environmental chambers with artificial daylight supplemented by five UV-B irradiance regimes to determine the range of growth and development responses of seedlings. Data from nine plant characteristics were assessed: leaf area, dry weight of leaves, stems and roots, tota! piant dry weight, height, ratio of roots to shoots and ieaf area to weight and rating of leaves for damage. Significant differences were observed in the responses noted. Stunting, leaf chlorosis and loss of apical dominance were three general symptoms apparent on all cultivars which received UV-B irradiance. Varying degrees of reduced leaf area and dry weight of the plants and altered ratios of weights of leaves per unit area and weight of roots to shoots were also found. It was concluded that different soybean cultivars demonstrate a marked difference in sensitivity to UV-B radiation under the artificial conditions of controlled environmental growth chambers and this may indicate a genetic basis for variability in sensitivity of soybean cultivars to this waveband. However, the sensitivity to UV-B radiation was inereased by the lower than normal photon fluence of photosynthetically active radiation (225 [J.E m~^s"^).

The combined effects of CO2 concentration and solar UV‐B radiation on faba bean grown in open‐top chambers

“…The increase of 77% for the C3 species Vicia faba at the final harvest as found in this experiment is consistent with other studies on similar crop species (Morison & Gifford 1984;Dijkstra, Schapendonk & Groenwold 1993). In general, UV-B radiation decreases biomass production (Teramura 1983;Caldwell & Flint 1994), although large differences in response between species and cultivars exist (Biggs, Kossuth & Teramura 1981). An explanation for the small effect of UV-B reduction on biomass production in the present experiment might be the relative low dose of UVBBE the plants received, as outlined in 'Materials and methods'.…”

Ambient levels of UV-B in Hawaii combined with nutrient deficiency decrease photosynthesis in near-isogenic maize lines varying in leaf flavonoids: Flavonoids decrease photoinhibition in plants exposed to UV-B

“…The decreased lightharvesting capacity would limit Chl a fluorescence and carbon assimilation through reductions in resonance transfer, electron transport, and ATP and NADPH production. Carbon allocation to the synthesis of Chl may be reduced, Chl photodegraded (Biggs et al 1981, Vu et al 1984, Tevini et al 1991, He et al 1994, Day and Vogelmann 1995, antenna size (Melis 1999), and the abundance of mRNAs that encode enzymes for Chl biosynthesis decreased (Strid et al 1990, Jordan et al 1991. Three of the elements that were deficient in the maize leaves (N, Fe, and Mn) play major roles in the photosynthetic complexes and their deficiencies decrease the contents of these complexes (Stocking 1975, Lawlor 1993.…”

“…In addition, the UV-B : PAR ratios are critical. PAR in growth chambers, combined with narrow-spectrum artificial sources of UV-B, increase the sensitivity of photosynthesis to UV-B (Biggs et al 1981, Deckmyn et al 1994, Teramura and Ziska 1996). However, many photoprotective processes require high ambient levels of PAR.…”

Steady state levels of D1 protein and psbA transcript during UV‐B inactivation of photosystem II in wheat

“…A comparison of results obtained from a series of earlier studies on UV-B effects on plants carried out in growth chamber, greenhouse and field conditions revealed that lower visible irradiance during growth as well as in the course of UV-B exposure increased the susceptibility of plants to UV-B (13,16,19,24,(25)(26)(27). High PAR on the other hand induced efficient adaptive and photorepair mechanisms, thereby protecting the plants from deleterious UV-B effects (23,(28)(29)(30).…”