Plant Decline Etiology in Poplar Short-Rotation Coppices
| Autor: | Naldo Anselmi1, Piero Paris2, L. Tosi2, M. Tarchi, P. Gothier1, L. Mugnai1, 3 |
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| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: | |
| Zdroj: | FAO, International Poplar Commission, Poplars and Other Fast-Growing Trees-Renewable Resources for Future Green Economies, pp. 77–77, Berlin, germany, 13-16/09/2016 info:cnr-pdr/source/autori:Naldo Anselmi1, Piero Paris2, L. Tosi2, M. Tarchi, P. Gothier1 and L. Mugnai1,3/congresso_nome:FAO, International Poplar Commission, Poplars and Other Fast-Growing Trees-Renewable Resources for Future Green Economies/congresso_luogo:Berlin, germany/congresso_data:13-16%2F09%2F2016/anno:2016/pagina_da:77/pagina_a:77/intervallo_pagine:77–77 |
| Popis: | The fight against Global Changes requires the development of renewable energy sources alternative to fossil fuels. For this purpose, a very important role is represented by biomass from short-rotation coppice (SRC) plantations of various forest plants, especially poplars (Populus spp.). With frequent coppicing cycles (every 3-5 years), one of the most serious problems of SRC is represented by stump mortality, usually attributed to physiological factors. In recent years, in some areas of central Italy, the stump mortality was particularly worrying, usually preceded by a more or less rapid shoots decline that seemed to be attributable to parasitic attacks. Investigations have therefore been conducted in order to determine the etiology of these phenomena, as well as to define the symptoms, the predisposing factors and the eventual clonal differences. The observations were conducted in poplar SRC plantations located in Viterbo-Italy (dry Mediterranean climate), established with three clones and a planting density of 6060 plants/ha. Plantations are managed with a 3 year-coppicing cycle, and observations were carried out on stumps on the first, second, and third year after coppicing. The various symptoms of the phenomenon over time and the degree of shoot decline were evaluated according to a suitable rating scale. We carried out in vitro isolation from altered tissues of diseased plants and pathogens identification were conducted through molecular analysis. The external symptoms began with the yellowing and sometimes necrosis of the leaves, microfilia, reduced shoots growth, followed by withering, usually maintaining attached the dead leaves to the shoot. The phenomenon culminated with the death of the stump. Throughout stump sectioning, we detected browning of internal tissues of roots and shoots base, gradually more and more deepening into the organs. In severe cases, we observed wood decay in central part of the stump, more or less deepening into the root system. The observed symptoms were almost zero on stumps one year after coppicing, very modest in the second year after coppicing, and increased a lot in the third year. In the light of laboratory analysis, it would appear that the phenomenon is due to a complex etiology disease, predisposed and triggered by various factors, leading some endophytic fungi to take pathogenic character, culminating with typical wood decay attacks. Among the already identified fungi, we isolated the genus Acremonium and some colonies of the order Hypocreales, and, among wood decay agents, the genus Pholiota and Collibia. Of the latter, we have also induced basidiocarps on toppled stumps stored in a controlled environment. According to our observations, it would seem that the studied die-off is similar to a complex disease, that seemed to be predisposed by loose soils, triggered by prolonged drought, and finally the die-off is manifested by attacks of various weakness pathogens. Although the phenomenon appears to be mainly concentrated on the central and southern Mediterranean areas of Italy, it is likely that with the Climate Change it can also extend to northern areas. The choice of soil with good water retention, the use of tolerant clones to water stress, the reduction of the coppicing frequency and, where possible, supplemental irrigation could represent appropriate measures to prevent or mitigate the phenomenon. |
| Databáze: | OpenAIRE |
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