| Sažetak (hrvatski) | U rod Paulownia, porodica Paulowniaceae, ubraja se od devet vrsta i nekoliko prirodnih hibrida koji od prirode rastu u Kini. Važne vrste u ovom rodu su: P. albiflora, P. australis, P. catalpifolia, P. elongata, P. fargesii, P. fortunei, P. kawakamii i P. tomentosa. U novije vrijeme hibridizacijom su dobiveni brojni hibridi s ciljem povećanja brzine rasta i prirasta te otpornosti na niske temperature. U Hrvatskoj se najčešće razmnožavaju hibridi paulovnije Shan Tong i 9501 iako postoje i drugi dobiveni vlastitim selekcijama. Cilj ovoga članka je objasniti načine razmnožavanja paulovnije u prirodi i problematiku njezine invazivnosti te razmnožavanje u rasadniku pomoću autovegetativne metode makropropagacije korjenovim reznicama. Postoje tri faze zakorjenjivanja reznica: inicijacija, indukcija i ekspresija. Postoji direktna i indirektna indukcija. Najosjetljiviji trenutak je povezivanje provodnih elemenata korjenčića i dijela stanice. Uspješnost pojave korjenčića na reznici ovisi o: fiziološkom stanju matične biljke, količini šećera, metabolizmu auxina, mineralnoj ishrani, metabolizmu fenola i dr. Postoje četiri faze razmnožavanja paulovnije iz korijenskih reznica: uzimanje i dorada korijenskih reznica s matične biljke u matičnjaku, pikiranje reznica u pvc lončiće ispunjene supstratom za zakorjenjivanje, zakorjenjivanje korjenskih reznica i osnivanje novog matičnjaka. Korijenske reznice paulovnije Shang Tong i 9501 uzimane su s obzirom na polaritet na način da se donji (distalni) dio korijena rezao pod kutom od 45 stupnjeva a gornji (proksimalni) pod kutom od 90 stupnjeva. Reznice su podijeljene su na kratke (8 cm) i dugačke (15 cm). Svaka skupina reznica dodatno je podijeljena na tanke i debele na način da razlika bude na oko vidljiva. Iz svake skupine u istraživanje je uzeto po 15 reznica. Napravljen je pokus na način da jedan dio reznica bude pikiran u grijanom stakleniku 7 dana od vađenja korijena a drugi dio nakon sušenja na sobnoj temperaturi u komori rasta. Prva skupina od 60 reznica uzeta je 14. prosinca i pikirana u perforirane pvc vrećice volumena 5,0 l i u gotovi supstrat za zakorjenjivanje Klasman Steckmedium. U supstrat za zakorijenjivanje dodano je 3g/l gnojiva s produženim djelovanjem treće generacije Osomocote Exact Standard 5-6M formulacije 15-9-12+2MgO+TE. Reznice nisu tretirane fitohormonom niti fungicidima protiv truleži. Pikiranje reznica je obavljeno na način da je gornja površina reza od 90 stupnjeva bila u razini supstrata. Duga skupina od 60 reznica stavljena je na sušenje u komoru rasta Kambič RK-980 CH. Temperatura u komori iznosila je 21 °C i relativna vlaga zraka od 40 % što predstavlja čuvanje reznica u konstantnim sobnim uvjetima. Reznice su čuvane u komori rasta 5 dana. Pikiranje je obavljeno na isti način kao i u slučaju prve skupine reznica 21.12.2017. godine. Prvo registriranje zakorjenjivanja obavljeno je 19.02.2018. godine što znači za prvu skupinu 67 dana od pikiranja a za drugu skupinu 60 dana od pikiranja. Sušenje reznica hibrida paulovnije Shan Tong dovelo do povećanja zakorjenjivanja u svim varijantama, a posebno je izraženo kod debelih reznica duljine 8 cm i debelih reznica duljine 15 cm. Može se preporučiti uzimanje debljih reznica i njihovo sušenje na sobnoj temperaturi u trajanju od 5 dana jer se dobiva značajnije veći postotak zakorjenjivanja. Pretjerana vlaga u supstratu za zakorjenjivanje korijenskim reznicama paulovnije negativno utječe na razvoj korijenskog sustava. Kod hibrida paulovnije 9501 također je utvrđeno kako sušenje reznica dovodi do povećanja zakorjenjivanja u svim varijantama, osim kod tankih reznica duljine 8 cm kod kojih je dobiven isti postotak zakorjenjivanja (33%). Posebno je zanimljiva situacija kod debelih reznica duljine 8 cm kod kojih se bez sušenja nije zakorjenila niti jedna reznica a sa sušenjem čak 80 %. Može se preporučiti uzimanje debljih reznica hibrida paulovnije 9501 i njihovo sušenje na sobnoj temperaturi u trajanju od 5 dana jer se dobiva značajnije veći postotak zakorjenjivanja. Postotak zakorjenjivanja reznica bez sušenja bio bi sigurno veći da su se uzele odmah nakon vađenja korijenskog sustava bagerom što se preporuča u praksi. U ovom slučaju minimalne temperature zraka od -4 °C i -5,6 °C dovele su do smrzavanja korijenskog sustava. Prosječna minimalna temperatura zraka u razdoblju od 8. do 14. prosinca. iznosila je svega 0,8 °C. Kod smrznutog korijena kora se odvaja rukom od drva a takve reznice ili propadaju ili tjeraju iz nižih adventivnih pupova. Korijenske reznice hibrida paulovnije Shan Tong i 9501 trebale bi se uzimati odmah nakon vađenja korijenskog sustava matične biljke a prosječne temperature zraka trebale bi biti iznad 0 °C. U ovim istraživanjima dokazana je štetnost temperatura od -4 °C i -5,6 °C na korijenske reznice jer su one dovele do njihovog smrzavanja. Najbolje kalendarsko vrijeme za vađenje korijenskih reznica, ovisno o godini, bilo bi u mjesecu ožujku. Utvrđena je mogućnost zakorjenjivanja korijenskih reznica hibrida paulovnije 9501 u običnoj vodi u kontroliranim uvjetima (bez svjetla, konstantna temperatura od 20 °C). Reznice su stavljene u „in vitro“ klijalicu Snijders Scientific B.V., ECD01E dana 21.12.2017. a fotografirane 21.02.2018. odnosno 62 dana od stavljanja u vodu. |
| Sažetak (engleski) | The genus Paulownia, family Paulowniaceae, contains about nine species and several natural hybrids which are native to China. Some important species in this genus include P. albiflora, P. australis, P. catalpifolia, P. elongata, P. fargesii, P. fortunei, P. kawakamii and P. tomentosa. More recently, numerous hybrids have been obtained by hybridisation for the purpose of increasing the rate of growth and increment, as well as develop resistance to low temperatures. In Croatia, the most commonly propagated are the Paulownia hybrids Shan Tong and 9501, although there are also other hybrids obtained by selections in some “in vitro” laboratory. The goal of this article is to explore different propagation methods of Paulownia in the nature, the problem of its invasiveness and nursery propagation by means of autovegetative macropropagation method from root cuttings. There are three phases of rooting the cuttings: initiation, induction and expression. There is direct and indirect induction. The most sensitive moment is the connecting of the conductive elements of small roots with parts of a cell. The success of root development on the cutting depends on the physiological status of the parent plant, sugar quantity, auxin metabolism, mineral nutrition, phenol metabolism and others. There are four stages of Paulownia propagation from root cuttings: digging out and finishing of root cuttings from the parent stock, pricking out the cuttings into plastic containers filled with potting media, rooting the cuttings and the establishment of a new parent stocks. The Paulownia root cuttings Shang Tong and 9501 were taken with regard to the polarity in the following way; the bottom (distal) part of the root was cut at an angle of 45 degrees and the upper (proximal) part was cut at an angle of 90 degrees. The cuttings were divided into short (8 cm) and long (15 cm) cuttings. Each group of the cuttings was additionally divided into thin and thick cuttings, making the difference visible to the naked eye. A total of 15 cuttings were taken from each group for the purpose of our research. In the experiment, one part of the cuttings was pricked out in a heated greenhouse 7 days after root excavation and the other part of the cuttings was pricked out after drying at room temperature in the plant growth chamber. The first group of 60 cuttings was taken on December 14th and pricked out in perforated 5.0 l plastic bags filled with ready-made Klasman Steckmedium rooting medium. The rooting medium was enriched with 3g/l of Osmocote Exact Standard 5-6M formulation 15-9-12+2MgO+TE, the 3rd generation of controlled release fertilizers. The cuttings were not treated with a phytohormone or rot prevention fungicides. The cuttings were pricked out in such a way that the upper surface of the cut at 90 degrees was at the level of the potting medium. The second group of 60 cuttings was dried in the Kambić RK-980 CH growth chamber. The chamber temperature was 21 °C and the relative air humidity was 40%, which equalled storage of the cuttings under constant room conditions. The cuttings were kept in the growth chamber for 5 days. Pricking out was performed on December 12th, 2017 in the same way as the first group of cuttings. The first rooting registration was done on February 19th, 2018, which in the case of the first group means 67 days after pricking out and for the second group 60 days after pricking out. Drying the Paulownia Shang Tong hybrid cuttings increased the rooting success in all the variants, and was particularly evident in thick cuttings 8 cm long and thick cuttings 15 cm long. Selecting thicker cuttings and drying them at room temperature for 5 days can be recommended because this procedure yields a significantly higher rooting percentage. Excessive moisture in the potting medium used for the Paulownia root cuttings negatively affects root system development. It was also confirmed that drying the Paulownia hybrid 9501 cuttings increases the rooting success in all the variants, with the exception of thin cuttings 8 cm long, where the rooting percentage was the same (33 %). Thick cuttings 8 cm long present a particularly interesting case, where not one single cutting which was not dried took root, while as many as 80 % of cuttings took root after being dried. Taking thicker cuttings of the Paulownia 9501 hybrid and drying them at room temperature for 5 days can be recommended, because this procedure yields a significantly higher rooting percentage. The rooting percentage of cuttings without drying would certainly be higher if the cuttings had been taken immediately after the root system was dug out with a dredge, as recommended in practice. In this case, the minimal air temperatures of -4 °C and -5.6 °C caused the root system to freeze. The average minimal air temperature in the period from December 8th to December 14th was only 0.8 °C. When the root is frozen, the bark is separated from the wood manually, and such cuttings either decay or sprouting from the lower adventitious buds. The root cuttings of the Paulownia hybrids Shan Tong and 9501 should be taken immediately after the root system of the parent plant is dug out, while the average air temperature should be above 0 °C. Our studies confirmed the harmful effect of temperatures from -4 °C and -5.6 °C on root cuttings, as such temperatures caused the cuttings to freeze. The best calendar period for digging out root cuttings, depending on the year, should be in March. It was confirmed that the root cuttings of Paulownia hybrid 9501 can also be rooted in ordinary water under controlled conditions (no light, constant temperature of 20 °C). The cuttings were placed in “in vitro” Snijders Scientific B.V., ECD01E germination table on December 21st, 2017, and were photographed on February 21st, 2018, or 62 days after being placed in the water. |
