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Abstract: Monografija obsega pregled znanja na področju prilagoditve oljk na sušne razmere ter pregled tehnologij namakanja oljk. Res je, da je oljka manj zahtevna vrsta, saj lahko uspeva v izjemno skeletnih tleh in je zelo dobro prilagojena na pomanjkanje vode v njih, a kljub fiziološkim prilagoditvam, lahko sušne razmere negativno vplivajo na rast, razvoj in pridelek oljk. Sušni stres lahko pri oljkah blažimo z deficitnim namakanjem. Deficitni način namakanja je oblika nadgradnje namakanja, saj z nadzorovanim primanjkljajem vode zagotovimo kakovost pridelka, obstoj rastline ter hkrati zmanjšamo porabo vode in energije. Deficitni način namakanja, temelji na načelu, da obrok vode dodamo takrat, ko ga rastlina najbolj gospodarno uporabi. Pri tem je ključnega pomena poznavanje rastlinske vrste, njenih anatomskih in morfoloških značilnosti, fizioloških prilagoditev na sušo, biokemijski odziv na stresne dejavnike in s tem vpliv na kakovost plodov in olja. Poleg tega je potrebno tudi poznavanje dejavnikov, ki vplivajo na pridelovalne sposobnosti oljk, kot so lastnosti tal s svojimi vodno zadrževalnimi sposobnostmi ter dostopna voda v tleh. Ob skrbnem upoštevanju potreb rastline in okoljskih razmer z ustreznim delovanjem namakalnega sistema lahko dosežemo usklajeno razmerje med kakovostjo in količino pridelka o hkratnem varovanju potencialov naravnih virov.
Published in DiRROS: 14.06.2022; Views: 365; Downloads: 273
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Abstract: Karst systems represent an important carbon sink worldwide. However, several phenomena such as the CO2 degassing and the exchange of cave air return a considerable amount of CO2 to the atmosphere. It is therefore of paramount importance to understand the contribution of the ecosystem to the carbon budget of karst areas. In this study conducted in a mid-succession ecosystem developed on abandoned karst grassland, two types of model were assessed, estimating the gross primary production (GPP) or the net ecosystem exchange (NEE) based on seven years of eddy covariance data (2013%2019): (1) a quadratic vegetation index-based empirical model with five alternative vegetation indices as proxies of GPP and NEE, and (2) the vegetation photosynthesis model (VPM) which is a light use efficiency model to estimate only GPP. The Enhanced Vegetation Index (EVI) was the best proxy for NEE whereas SAVI performed very similarly to EVI in the case of GPP in the empirical model setting. The empirical model performed better than the VPM model which tended to underestimate GPP. Therefore, for this ecosystem, we suggest the use of the empirical model provided that the quadratic relationship observed persists. However, the VPM model would be a good alternative under a changing climate, as it is rooted in the understanding of the photosynthesis process, if the scalars it involves could be improved to better estimate GPP.
Keywords: eddy covariance, carbon flux, GPP, NEE, vegetation indices, remote sensing, satellite data, GPP map
Published in DiRROS: 03.01.2022; Views: 434; Downloads: 308
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Keywords: stabilni izotopi, masna spektrometrija, laserska absorpcijska spektroskopija, EA-IRMS, OA-ICOS
Published in DiRROS: 03.11.2021; Views: 511; Downloads: 187
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Published in DiRROS: 03.11.2021; Views: 432; Downloads: 131
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Abstract: Increased frequency and severity of stressful events affects the growth patterns and functioning of trees which adjust their phenology to given conditions. Here, we analysed environmental effects (temperature, precipitation, VPD and SWC) on the timing of leaf phenology, seasonal stem radial growth patterns, and xylem and phloem anatomy of Quercus pubescens in the sub-Mediterranean in the period 2014%2019, when various adverse weather events occurred, i.e. spring drought in 2015, summer fire in 2016 and summer drought in 2017. Results showed that the timings of leaf and cambium phenology do not occur simultaneously in Q. pubescens, reflecting different environmental and internal constraints. Although year-to-year variability in the timings of leaf and cambial phenology exists, their chronological sequence is fairly fixed. Different effects of weather conditions on different stages of leaf development in spring were observed. Common climatic drivers (i.e., negative effect of hot and dry summers and a positive effect of increasing moisture availability in winter and summer) were found to affect the widths of xylem and phloem increments with more pronounced effect on late formed parts. A legacy effect of the timing of leaf and cambial phenology of the previous growing season on the timing of phenology of the following spring was confirmed. Rarely available phloem data permitted a comprehensive insight into the interlinkage of the timing of cambium and leaf phenology and adjustment strategies of vascular tissues in Mediterranean pubescent oak to various environmental constraints, including frequent extreme events (drought, fire). Our results suggest that predicted changes in autumn/winter and spring climatic conditions for this area could affect the timings of leaf and stem cambial phenology of Q. pubescens in the coming years, which would affect stem xylem and phloem structure and hydraulic properties, and ultimately its performance.
Keywords: pubescent oak, leaf development, radial growth, initial earlywood vessel, sieve tube, anatomy, cambial cell production, extreme weather events
Published in DiRROS: 06.09.2021; Views: 657; Downloads: 112
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