Effects of ultraviolet‐B irradiation on plants during mild water stress.

Abstract

Cucumber (Cucumis sativus L. cv. Delikatess) and radish (Raphanus sativus L. cv. Saxa Treib) were grown in a factorial design under two ultraviolet‐B (UV–B) irradiances and three levels of water stress. On a weighted, daily dose basis the UV–B radiation treatments were equivalent to ambient levels during the beginning of the growing season (controls) and those predicted for an 11.6% ozone depletion during the summer solstice at 49°N latitude. Water stress was achieved by varying the frequency of watering. The combination of UV–B radiation and water stress resulted in large species differences in the pattern of stomatal resistances. This study indicated that Cucumis is one of the most sensitive crop species to UV–B radiation yet identified and that the primary effect of UV–B radiation in this species is a decrease in the leaf diffusive resistance to water vapor. This, therefore, may result in reductions in growth via increased water stress.

Polyphenol Increases in Safflower and Cucumber Seedlings Exposed to Strong Visible Light with Limited Water

“…Tevini et al 20,21) reported that the water stress caused decreases in the fresh weights and leaf areas in cucumber seedlings. Similar observations were also reported by Yang et al 22) In our results, the fresh weights of leaves in the cucumber seedlings greatly decreased due to the water stress that was added to the stress of the strong light radiation (Table 1), which is consistent with the results from these previous reports.…”

Effects of Ultraviolet-B Irradiance on Soybean

“…Only a few studies have employed UV-B doses equivalent to less than a 20% reduction in the ozone layer. Nevertheless, these studies have also demonstrated the deleterious effects of UV-B irradiation upon plants (24)(25)(26)(27).…”

“…Only a few studies have employed UV-B doses equivalent to less than a 20% reduction in the ozone layer. Nevertheless, these studies have also demonstrated the deleterious effects of UV-B irradiation upon plants (24)(25)(26)(27).In addition to unrealistically high UV-B irradiances, another criticism of many previous UV-B studies has been the low PPFD under which the plants were grown and irradiated. Only a few studies have examined the effects of UV-B radiation on plants grown under relatively high PPFDs, which more approximate natural conditions (24, 25).…”

“…An increase in UV-B irradiance is of particular concern since energy in this waveband is readily absorbed by proteins and it has been demonstrated that plant processes such as photosynthesis (25), transpiration (7,25), leaf expansion (10,23,26,27), dark respiration (22,25), and biomass allocation (24) are affected. In the majority of UV-B studies, the UV-B dose utilized was 3-to 5-fold greater than the National Academy of Science's most recent estimates.…”

Changes in photosynthesis and carbohydrate synthesis in response to elevated UV-B environment

“…A modulated fluorimeter (PAM-2000, Walz, Germany) was used to estimate ∮PSII simultaneously with Asa t, and Fv/Fm was measured after 30 min dark-adaptation (Damian et al, 1998). 일부 연구결과에 따르면 UV-B 조사에 의해 기공전도도가 감소하는 것이 밝혀졌다 (Teramura et al, 1983;Negash, 1987;Dai et al, 1992;Middleton and Teramura, 1993). (Murali and Teramua, 1986;Sullivan and Teramura, 1989;Teramura et al, 1991;Ziska and Teramura, 1992;Middleton and Teramura, 1993;Damian et al, 1998).…”