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Arbuscular mycorrhiza - partner in communication

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Arbuscular mycorrhiza is one of the most common type of mycorrhiza in plant kingdom. Process of plant root colonization by arbuscular mycorrhizal fungi is consisted of four phases: presymbiotic phase, phase of contact and hyphae penetration to the roots, growth phase of hyphae inside the roots and phase of mycorrhizal intracellular structure development. The formation of symbiosis between fungi and host plant requires the exchange of molecular signals between these organisms. Plant signal molecules are described as strigolactones and cutin monomers whereas fungal signal molecules are lipo-chito-oligo-saccharides and short chito-oligosaccharides. During the contact with plant roots fungal hyphae form appresorium on the surface of epidermis. After appresorium creation, the pre-penetration apparatus (PPA) is formed in plant cell, which is a structure defining a route of the hyphae overgrowing across the plant cell. Afterwards the fungus penetrates the epidermal cell and the cell of root cortex, where hyphae leave the cell and enter into appoplast, growing and branching along the root axis.
The potential of mycorrhization of lettuce in hydroponic conditions was tested in a two-year experiment carried out in the autumn of 2011 and 2012 in an unheated foil tunnel. The experimental factors were as follows: inoculation of plants with arbuscular mycorrhizal fungi (AMF+ or AMF-), concentration of phosphorus in a nutrient solution (10 or 40 mg dm-3) and the type of substrate (rockwool or coconut coir). The inoculation of plants with arbuscular mycorrhizal fungi of the genus Glomus was performed twice, i.e. while sowing seeds and when planting lettuce plants into mats. The impact of the experimental factors on the degree of colonization of lettuce roots by AMF as well as the yield and nutritional status of plants, expressed as the content of macro- and micronutrients, was studied. The mycorrhizal frequency in roots inoculated with AMF reached 51.36%. The nutrient solution concentration of phosphorus and the type of substrate did not have any significant effect on the mycorrhizal frequency. There were no differences in the yield and content of macronutrients in lettuce leaves between plants inoculated and not inoculated with AMF (AMF+, AMF-). Likewise, there were no differences in the yield caused by different phosphorus levels in the nutrient solution or the types of substrate. Plants growing on rockwool accumulated significantly less P, Ca and Mg in comparison to plants growing on coconut coir. Regarding Ca, this effect was especially pronounced in plants receiving the nutrient solution with a higher concentration of P, i.e. 40 mg dm-3. Mycorrhiza had a significant effect on the content of Cu, Mn and Zn in lettuce leaves. Inoculated plants were characterized by a lower content of these micronutries compared to plants grown without AMF. With respect to Mn, this effect was particularly evident in plants grown on rockwool.
Many attempts have been made to develop a strategy for regulating forest use consistent with the multifunctional forest model. In this paper we present two proprietary methodologies of regulation of the allowable cutting size in a multifunctional forest in the 60−year time perspective. We assumed that all restrictions of nature protection and non−productive functions of the forest would still be in force. We based the first method on age class tables (TKW), which is faster but less exact in terms of spatial order of felling. The tree stand method (D−STAN) is based on stands spatial order and the cutting direction basis. In both cases, we based the temporal felling order on species rotation age. Comparing the results, we noticed that they present similar trends in the age structure of tree stands in younger age classes. The main discrepancies of the forecast concerns the share of forest stands in a complex structure: the TKW method gave approximately 12,4%, while the D−STAN one produced 5,1%. The latter approach shows that much smaller areas of stands are used for reconstruction. That marker is influenced by the spatial order of cutting used in the D−STAN model. In conclusion, we suggest to return to the big−area clear−cutting system on fresh coniferous habitats. Medium−area clear−cuttings should be brought back on the least fertile fresh mixed coniferous forests and possibly even fresh mixed deciduous forests.
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