RESUMEN
Apple production is a dynamic agricultural system in which pesticides are applied recurrently to control pests and diseases in the orchards. Understanding the impact of such agents on non-target organisms is crucial to minimise unintended consequences while maintaining their use in crop protection. The aim was to test how fungicide, herbicide, elicitor, and their combinations affect the physiology of the epiphytic moss Hypnum cupressiforme that naturally occurs in orchards. Our results showed that both dodine and diflufenican applied separately had a strong negative effect on moss physiology reflected in significantly decreased photosynthetic pigment contents, maximum quantum yield of PSII photochemistry, cell membrane integrity and dehydrogenase activity, and increased membrane lipid peroxidation, which indicates a high physiological stress. Furthermore, the combined use of herbicide and fungicide resulted in further deterioration of the physiological condition compared to the effects of both agents used separately. In many cases, the application of chitosan together with a diflufenican or dodine resulted in a reduction of the negative effects triggered by these agents. The compensatory effect was particularly pronounced in maintaining a low level of cell membrane permeability. Consequently, it can be concluded that chitosan could have a protective function against cell membrane damage in non-target mosses.
Asunto(s)
Briófitas , Bryopsida , Quitosano , Fungicidas Industriales , Guanidinas , Herbicidas , Malus , Fungicidas Industriales/toxicidad , Herbicidas/toxicidad , Briófitas/química , Bryopsida/químicaRESUMEN
Biological soil crust (BSC) constitutes a consortium of cyanobacteria, algae, lichen, mosses, and heterotrophic microorganisms, forming a miniature ecosystem within the uppermost soil layer. The biomass of different organisms forming BSC and their activity changes along with succession. Previous studies focused primarily on BSC in hyper-arid/arid regions, whereas the ecophysiology of BSC in temperate climates is still not well recognized. In order to determine changes in overall microbial activity and photosynthetic biomass in BSC at different stages of the succession of inland sandy grasslands, we analyzed dehydrogenase activity and determined the content of photosynthetic pigments. We also compared these parameters between BSC developed on the dune ridges and aeolian blowouts in the initial stage of succession. Our study revealed a significant increase in both photosynthetic biomass and overall microbial activity in BSC as the succession of inland shifting sands progresses. We found that chl a concentration in BSC could be considered a useful quantitative indicator of both the presence of photoautotrophs and the degree of soil crust development in warm-summer humid continental climates. The photosynthetic biomass was closely related to increased microbial activity in BSC, which suggests that photoautotrophs constitute a major BSC component. Dune blowouts constitute environmental niches facilitating the development of BSC, compared to dune ridges. High biomass of microorganisms in the dune blowouts may be associated with a high amount of organic material and more favorable moisture conditions. We conclude that deflation fields are key places for keeping a mosaic of habitats in the area of shifting sands and can be a reservoir of microorganisms supporting further settlement of dune slopes by BSC.
Asunto(s)
Ecosistema , Suelo , Biomasa , Microbiología del Suelo , Clima DesérticoRESUMEN
Lichens are symbiotic organisms that are generally sensitive to air pollution due to their specific biological and physiological features. Physcia adscendens is a nitrophilous lichen well-known for being resistant to air pollution associated with progressive anthropopressure. The aim of this study was to investigate the effect of nitrogen oxides and suspended particulate matter (PM10 and PM2.5) on anatomical structure of the thallus and photobiont's photosynthetic efficiency in P. adscendens inhabiting sites that differ in terms of air pollution level and thereby to determine the relevance of these pollutants for shaping the structure of the thallus and the physiological condition of the photosynthetic partner. We found that P. adscendens from polluted sites had increased thickness of the algal layer and the larger size of the algae cells, but a much lower ratio of the algal layer to the whole thallus. Lichens from highly polluted sites had also higher photosynthetic efficiency, which indicates a relatively good physiological condition of the photobiont. This indicates that the photobiont of P. adscendens is well-adapted to function under air pollution stress which may contribute to its success in colonizing polluted sites. Both changes in the anatomy of the lichen thallus and the efficiency of photosynthesis may be related to the enrichment of the environment with nitrogen. The increased photosynthetic efficiency as well as investment in the size of photobiont cells and growth mycobiont hyphae confirms that P. adscendens is well-adapted to urban conditions; however, the mechanism behind those adaptations needs more focus in the context of global environmental changes.