When natural regeneration of Quercus robur stands is hampered by an insufficient acorn yield, human assisted sowing of acorns collected in non-affected stands and stored for some period of time is performed. To inhibit the development of fungi and acorn deterioration during storage, thermotherapy is usually applied by submerging acorns for 2.5 h in water heated to 41 °C. This research aimed to test the effect of four thermotherapy treatments of different durations and/or applied temperatures as well as short-term storage at −1 °C or 3 °C on acorn internal mycobiota and germination. Fungal presence in cotyledons was analyzed in 450 acorns by isolation of mycelia on artificial media, followed by a DNA-based identification. Germination of 2000 acorns was monitored in an open field trial. Thermotherapy significantly decreased fungal diversity, while storage at 3 °C increased the isolation frequency of several fungi, mainly Penicillium spp. The most frequently isolated fungi did not show a negative impact on acorn germination after short-term storage. The study confirmed the efficiency of thermotherapy in the eradication of a part of acorn internal mycobiota, but also its effect on the proliferation of fast-colonizing fungi during storage. However, the latter showed to be more stimulated by storage conditions, specifically by storage at 3 °C.
The quantity and quality of seedlings in the nursery has an impact on the success of re-establishment and later growth. High germination rates enable a sufficient number of seedlings, and their quality is assessed using a number of parameters, including seedling height and root collar diameter. These parameters are influenced in some species by seed size, but the correlation between them is species-specific. The model species in this research was sweet chestnut (Castanea sativa Mill.), and seeds from 12 populations from two distinct biogeographical regions of Croatia were collected. We examined the influence of seed size on four parameters: germination rate, seedling height, root collar diameter and sturdiness quotient. Seed size has been shown to have a positive influence on both seedling height and root collar diameter, whereas no such correlation was noted for germination rate and sturdiness quotient. Significant differences in nut size and seedling growth parameters were found between the Mediterranean and continental populations, with higher values observed in the coastal Mediterranean populations. We concluded that seed origin and seed size have a significant impact on seedling growth and are important factors to consider when choosing seed material. Further nursery operations should consider seed origin and local environmental conditions when choosing seedlings for reforestation efforts and general forest operations.
Narrow-leaved ash (Fraxinus angustifolia Vahl) is one of the most important tree species of lowland floodplain forests. In the Republic of Croatia, this tree species is found in pure stands, but more commonly mixed with other broadleaves, including pedunculate oak, black alder, lowland elm, spreading elm, poplars and other species. The basic ecological factors that determine the occurrence of this forest tree species are micro-depressions in which water is retained after frequent flooding, and clayey alluvial soil which prevents water drainage. Due to these factors, forests of narrow-leaved
There is a growing trend in the world of planting fast growing species (rotations 5 to 10 years). Their primary purpose is the production of wood fibers and biomass, but they certainly represent the potential in making solid wood products as well. One of the fast-growing species is Paulownia sp., a species of extremely fast growing wood. Plantation breeding of Paulownia sp. in Croatia is increasing, although there is a little knowledge about the technical properties of Paulownia wood and its end use is questionable. This paper presents preliminary results of some physical properties of juvenile wood of two Paulownia hybrids planted in the area near the town of Glina in the Republic of Croatia. One hybrid is 9501 ((Paulownia fortunei × Paulownia elongata) × (Paulownia fortunei × Paulownia tomentosa)) and the other hybrid is Shan Tong (Paulownia fortunei × Paulownia tomentosa). The aim of this study was to investigate physical properties of juvenile wood of two Paulownia hybrids from one site in Croatia, to determine differences in physical properties of wood between two hybrids and to evaluate the correlation between density and shrinkages of each hybrid. Significant differences in oven dry density, basic density and density at maximum MC, between the two hybrids were determined. There is no statistically significant difference in longitudinal, radial, tangential and volumetric shrinkages between the two hybrids.
U ovom stručnom članku detaljno su opisani svi čimbenici koji utječu na uzgoj kvalitetne šumske sadnice poljskog jasena za umjetnu obnovu i pošumljavanje. Do sada se pozornost nije poklanjala kvaliteti sadnica s obzirom na nove i potpuno promijenjene nepovoljne ekološke i biološke čimbenike koji se događaju sa sastojinama poljskog jasena u Hrvatskoj. Kvaliteta sadnica poljskog jasena određivala se isključivo jednim morfološkim čimbenikom, a to je najčešće visina izbojka što nije dobro. U radu su definirani pojmovi morfološke i fiziološke kvalitete sadnica. Opisane su metodologije za mjerenje morfoloških i fizioloških svojstava šumskih sadnica i njihov značaj na preživljenje, rast i prirast nakon sadnje na terenu. Morfološka svojstva su: visina izbojka, promjer stabljike, odnos visine izbojka i promjera stabljike, duljina pupa, volumen korijena i stabljike, težina sadnica, odnos volumena izbojka i korijena te boja, forma i oštećenja. Fiziološka svojstva su: otpornost na hladnoću, potencijal rasta korijena (PRK), dormantnost pupa i koncentracija hranjiva u lišću. Opisana su tri stresna čimbenika koja utječu na smanjenje kvalitete šumskih sadnica, preživljenje, rast i prirast na terenu, a to su: stres zbog vlage u biljci (PMS), stres zbog temperature i fizički stres (padanje, gnječenje, vibracije, površinsko oštećivanje i trganje korijena). Definirani su i svi ostali stresni čimbenici koji utječu na pad kvalitete šumske sadnice koji se događa u razdoblju od vađenja u rasadniku do sadnje na terenu. Razjašnjena je uloga pojedinog stresnog čimbenika na sadnice, kao i kumulativan utjecaj više stresnih čimbenika. U članku se govori o ispravnom rukovanju sadnicama od vađenja u rasadniku do pošumljavanja. Prikazane su novije patentirane mogućnosti zaštite sadnica od trenutka vađenja iz rasadnika ili kamiona-hladnjače do sadnje na terenu.
Maruni su selekcionirane sorte europskog pitomog kestena, uzgajane radi krupnoće i kvalitete plodova. Većina zemalja u kojima raste europski pitomi kesten ima svoje autohtone sorte, koje su dobivene dugotrajnom selekcijom i uzgojem, tijekom više stoljeća. Kultiviranje maruna ima dugu povijest u zapadnoj Hrvatskoj, većinom na području Lovrana i okolice. Nažalost, stabla maruna ugrožena su štetnicima i bolestima, kao i napuštanjem nasada, no dio uzgajivača i dalje njeguje tradicionalan način uzgoja. U ovome se radu daje pregled najčešćih metoda vegetativnog razmnožavanja pitomog kestena i maruna, kao i kraći pregled načina uzgoja, razmnožavanja te značaja nasada maruna u Hrvatskoj. Budući da je prenošenje istovjetnih karakteristika plodova s matične biljke na potomstvo moguće jedino izravnim prenošenjem genotipa roditeljske biljke, maruni se mogu razmnožavati samo vegetativnim metodama. Najčešća metoda vegetativnog razmnožavanja maruna, kao i pitomog kestena, u rasadnicima je cijepljenje. Ostale korištene metode vegetativnog razmnožavanja su razmnožavanje povaljenicama, reznicama i kulturom tkiva.
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