https://spar.msstate.edu/class/EPP-2008/Chapter%201/Reading%20material/Ozone,%20UV-B%20and%20Others/UV-B%20Review-AFM-03.pdf

Field crop responses to ultraviolet-B radiation: a review

An attempt has been made to assess the UV-B-protective capacity of phenolic compounds accumulated In superficial structures of plants using apple fruit as a model. Two apple (Malus domestica Borkh.) cultivars (Braeburn and Granny Smith) differing in response to high fluxes of solar radiation were selected and exposed to increasing doses of UV-B radiation. The extent of UV-B-induced damage to photosystem II of apple skin correlated with its quercetin glycoside (but not anthocyanin) content. Granny Smith apples did not demonstrate a pronounced response to high sunlight In terms of the accumulation of phenolic substances in the skin and exhibited similar patterns of F o , F m , and F v /F m changes in the course of UV-B irradiation both on sun-exposed and shaded surfaces of a fruit. Unlike Granny Smith, Braeburn fruits were characterized by a significant accumulation of quercetin glycosides in sun-exposed skin, however, shaded skin contained these compounds In similar amounts to those in Granny Smith. Accordingly, photosystem II in sun-exposed skin of Braeburn apples was resistant to high doses of UV-B radiation (up to 97 kJ m -2 ), whereas the susceptibility of the photosynthetic apparatus in shaded skin of Braeburn to UV-B-induced damage was much higher and similar to that of both sun-exposed and shaded skin of Granny Smith fruits. Anthocyanins, at least in the amounts found in Braeburn, did not show an additional effect in UV-B protection.

Significance of skin flavonoids for UV‐B‐protection in apple fruits

Nucleocytoplasmic plant lectins.

In the experiment conducted in the greenhouse, the different doses of UV-B radiation applied to the two species Avena fatua and Setaria viridis induced changes in leaf and plant morphology. It was a decrease of plant height, fresh mass of leaves, shoots and roots as well as leaf area. Besides, it caused the leaf curling in both of the species. The significant differences between Avena fatua and Setaria viridis in the studied traits were mainly due to the tillering ability of the species. The content of chlorophyll varied considerably. The average values of leaf greenness (SPAD units) for oats were about 43 while for green foxtail 32, respectively. U-VB did not reduce leaf weight ratio, shoot dry matter, shoot to root ratio and leaf area ratio.

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The effect of UV-B radiation on plant growth and development

The depletion of the stratospheric ozone layer leads to an increase in the level of ultraviolet-B radiations reaching the Earth's surface. UV-B radiations are known to have damaging effects on all forms of life. In plants, the UV-B exposure leads to the generation of reactive oxygen species (ROS), eventually resulting in oxidative stress. ROS induce lipid peroxidation of biological membranes, destroy the natural lipid-soluble antioxidants, and alter the expression of several genes through nonspecific signaling pathways. The integration of the thylakoid membrane appears to be much more sensitive than the activities of the photosynthetic components bound within. However, the decrease of mRNA transcripts in the photosynthetic complexes and other chloroplast proteins are among the early events of UV-B damage. Other genes, encoding defense-related proteins are rapidly upregulated under UV-B irradiation. UV-B radiation induced production of ROS, increased the antioxidant capacity and thus, minimized the magnitude of negative impact of UV-B on plants. Specific signaling pathway includes the UVR8 component that regulates the expression of a set of genes essential for the protection of plant against UV-B. This chapter comprises information regarding the UV-B perception, signal transduction, regulation of gene expression, ROS formation, and its metabolism from various studies performed under growth chamber, green house, and field conditions.

Chapter 3 Ultraviolet-B Induced Changes in Gene Expression and Antioxidants in Plants

Ultraviolet-B radiation (biologically effective dose 2.6 kJ m−2 d−1) had negative influence on morphology and physiology of the young triticale plants. Plants exposed to UV-B were of lower height than control plants, their leaves were narrow, and the rate of net photosynthesis was decreased. The line RAH 336, which wax cover is lesser than that of traditional cultivar Magnat, was more susceptible to UV-B radiation, considering primary photosynthesis reactions, recorded by chlorophyll a fluorescence. An activation of protective mechanisms was observed: plants responded to UV-B by an increase of the content of UV-B absorbing compounds, and changes of antioxidant enzyme activities.

Influence of UV-B radiation on young triticale plants with different wax cover

Pea plants were more susceptible to long-wave UV-B irradiation (305 – 320 nm, 7.7 kJ m−2 d−1, 4 weeks) in comparison with the triticale. This difference was more apparent from the changes in total area of leaves and dry mass of shoots, rather than from the parameters of chlorophyll fluorescence and net photosynthetic rate.

Responses of pea and triticale photosynthesis and growth to long-wave UV-B radiation.

Adjuvants used as a component of pesticide formulations or spray adjuvants can change agronomic effects (effectiveness, phytotoxicity) of the product. An adjuvant may also affect the environmental impact, as dispersion patters may be altered, the functional activity period of the active ingredient may be lengthened, or its degradation delayed (Swarcewicz, 2002). The pesticides atrazine and coumaphos were degraded at a lower rate and to a lower extent in the presence of a nonionic surfactant (Mata-Sandoval et al., 2001). Addition of nonionic surfactants to soil decreases the mobility of the pesticides, which are probably adsorbed to the surfactants previously adsorbed to the soil. The mobility in soil of the pesticides diazinon, atrazine and acephate decreased in the presence of nonionic surfactants (Sanchez-Camazano et al., 1995; Iglesias-Jimenez et al., 1996). Soil organic matter is the primary soil constituent responsible for sorption of nonionic pesticides and surfactants in pesticides (Krogh et al., 2003). Atrazine is potentially toxic both to humans and to the ecosystem. It is a hydrophobic pesticide frequently found during monitoring of pesticides in aquifers in various countries (Carter, 2000). The aim of this study was to (i) determine contact times required for attainment of sorption equilibrium and (ii) explore the effect of Atpolan on the amount of atrazine sorbed by soil of varying organic carbon content. Materials and Method

Adsorption of Atrazine by Soils Varying in Organic Carbon Content in the Presence of the Adjuvant Atpolan

This paper presents a quick chlorophyll fluorescence method for the estimation of the influence of some adjuvants applied with Azoprim 50WP (a.s. atrazine) or Buramet 70WG (a.s. metamitron) on oat plants. These herbicides inhibit photosynthetic electron transport in photosystem II, which was measured by means of a pulse PAM-210 chlorophyll fluorometer. Results of the ETR measurements show differences between the efficacies of the studied adjuvants. Olemix 84EC, Atpolan 80EC, Adpros 85 SL and Break-Thru S-240 were the most effective in the mixture with Azoprim, and the last two--also in the mixture with Buramet. Olejan 85 EC did not change the biological action of Azoprim nor Buramet. Moreover, the most effective adjuvants showed relatively good stability.

E. Skorska

Papers

Influence of UV-B radiation on young triticale plants with different wax cover

Responses of pea and triticale photosynthesis and growth to long-wave UV-B radiation.

Adsorption of Atrazine by Soils Varying in Organic Carbon Content in the Presence of the Adjuvant Atpolan

Confocal microscopy confirms the presumed cytoplasmic/nuclear location of plant, fish and fungal orthologs of the Galanthus nivalis agglutinin.

Influence of buthidazole, diuron, and atrazine on some light reactions of photosynthesis.