The Promotive Effect of Selenium on Plant Growth as Triggered by Ultraviolet Irradiation

Abstract

Selenium is known to be important in antioxidation in human and animals, but little attention has been paid to its role in higher plants. Chemically it is a photovoltaic element, and in order to study its effects on plants, ryegrass (Lolium perenne L.) and lettuce (Lactuca sativa L.) were cultivated in a pot experiment without or with H2SeO4 (0.1 and 1.0 mg Se kg−1) under normal light or subjected to UV(B)‐irradiation episodes. Without Se addition, UV(B) diminished markedly the yield of lettuce (by 8%) but not that of ryegrass. The lower Se dosage had no effect on yields under normal light conditions, but in combination with UV(B) it enhanced plant growth. This indicates that UV light acted as a trigger for the growth‐promoting effect of Se. The higher Se dosage was toxic to plants, but the toxicity was alleviated under UV(B). The positive interaction between the high‐energy light and Se was manifested also as increased concentrations of nucleic acids and soluble proteins. The synergistic effect was partly attributable to the antioxidative function of Se, shown as inhibition of lipid peroxidation and promotion of glutathione peroxidase (GSH‐Px) activity. Some other possible mechanisms of the positive action of Se are discussed.

The ameliorative effect of selenium on Azolla caroliniana grown under UV-B stress

“…With Se, UV-treated Azolla plants' biomass and protein content were 1.8 to 1.6-fold those of UV-treated plants without Se, respectively (Table 1). Similarly, some studies have demonstrated the benefits of adding a small amount of Se, including increased tuber yield and starch concentration in young potato leaves (Turakaine et al 2004), and increased growth in ryegrass and lettuce exposed to UV-B radiation (Hartikainen and Xue 1999;Pennanen et al 2002).…”

“…The addition of Se at low concentrations alleviated the oxidative stress caused by UV irradiation in lettuce (Lactuca sativa L.) and ryegrass (Lolium perenne L.) (Hartikainen and Xue 1999;Hartikainen et al 2000), and in strawberry (Fragaria x ananassa Duch.) (Valkama et al 2003).…”

Does antioxidant capacity of leaves play a role in growth response to selenium at different sulfur nutritional status?

“…In number of previous works, an amelioration of stresses such as UV radiation Xue 1999, Xue and, cold injury (Seppänenn et al 2003) and aging (Xue et al 2001) by Se was attributed to the activation of antioxidant defense system of plants. However, in our experiment the positive effect of Se was observed in non-stressed plants and in the early growth period.…”

Impact of selenium enrichment on seed potato tubers

“…In this regard, potato is classified as a Se non-accumulator plant. Even though higher plants are thought not to require Se, there are increasing indications that at low concentrations, Se acts as an antioxidant and can promote plants growth and strengthen the capacity of plants to resist the oxidative stress caused by reactive oxygen species produced by internal biochemical reactions and external factors (Hartikainen and Xue 1999, Xue et al 2001, Pennanen et al 2002, Seppänen et al 2003, Djanaguiraman et al 2005, Kong et al 2005), whereas at higher concentrations it acts as a pro-oxidant inducing oxidative stress and reducing the yields , Cartes et al 2005. Previous studies have shown that added Se will be efficiently absorbed by leaves of potato plants and transported to the tubers (Turakainen et al 2004a(Turakainen et al , b, 2006, and it is transferred from seed tubers to the tubers of next progeny (Turakainen et al 2006).…”