Explant browing of in vitro cultured olives (Olea europaea L.)

Mikropropagacija predstavlja vrlo efikasan alat za masnovno širenju gospodarsko važnih vrsta voćaka u koje se ubraja i maslina. Ovo istraživanje provedeno je s ciljem ispitivanja mogućnosti mikropropagacije (sterilizacije, sprječavanja fenolnog posmeđenja i proliferacije) eksplantata masline (Olea europaea L.) u laboratoriju za kulturu biljnog tkiva (labaratorij za voćarstvo) na Poljoprivredniom fakultetu u Osijeku. Nodijalni eksplantati inicirani su na WPM hranjivu podlogu koja je uključivala tretmane s dva različita citokininska hormona (COCO = kokosova voda + BAP 6-Benzylaminopurin; i GA3 = giberelinska kiselina + BAP 6-Benzylaminopurin) u indukciji proliferacije eksplantata masline s kombinacijom stavljanja eksplantata u mrak i bez mraka kao jedna od metoda u sprječavanju oksidacije fenola. Ostali predtretmani korišteni u cilju smanjenja fenolne oksidacije uključivali su aplikaciju PVP i antioksidativnog miksa. Kultivar Oblica rezultirao je vrlo visokom stopom mortaliteta nakon 30 dana od 68%, kultivar Drobnica 53% i Rosulja 30%. Proliferacija je bila uspješna na samo 3 od ukupno 120 eksplantata (uspješnost proliferacije 2.5%) i to kod kultivara Rosulja (1 eksplantat) i Drobnica (2 eksplantata). Eksplantati kultivara Drobnice koji su inducirali proliferaciju bili su pod djelovanjem citokininskog tretmana koji je sadržavao kokosovu vodu te su eksplantati proveli prva 3 dana u mraku. Također kod kultivara Rosulja eksplantat koji je inicirao proliferaciju bio je 3 dana u mraku. Kokosova voda u kombinaciji s BAP-om (50ml/l + 0.5ml/l) rezultirala je učinkovito u proliferaciji i daljnjem rastu eksplantata masline. Otpuštanje fenolnih komponenti koje su vidljive u mediju, ali i nekih drugih štetnih tvari koje nisu vidljive golim okom dovode do smrti eksplantata ne samo masline nego i drugih strateški važnih voćnih vrsta u in vitro modelu proizvodnje. Daljnja istraživanja potrebno je usmjeriti na preciznije određivanje različitih kombinacija koncentracija hormona na bazi kokosove vode, odnosno adsorbanata i metoda u supresiji nakupljanja toksično štetnih fenolnih tvari.Micropropagation is a very effective tool for the mass propagtion of economically important types of fruit seedling, including olives. This study was conducted to investigate the possibility of micropropagation (sterilization, prevention of phenol degradation and proliferation) olive (Olea europaea L.) by nodal explants. The research was set up in the laboratory for in vitro production at Faculty of Agriculture in Osijek (Chair of Horticulture – Fruit growing). Nodal explants were initiated on a WPM nutrient medium that included treatments of two different cytokine hormones (COCO = Coconut Water + BAP 6Benzylaminopurine; and GA3 = Giberelic Acid + BAP 6-Benzylaminopurine) with placing the explants into the dark and without darkness as one of the methods to prevent phenol oxidation. Other pre-treatments used to reduce phenolic oxidation include PVP and antioxidant mix applications. Cultivar Oblica resulted with a high mortality rate after 30 days with 68%, cultivar Drobnica 53% and Rosulja 30%. Proliferation was successful at only 3 of total 120 explants (proliferation efficiency 2.5% = Rosulja cultivars 1 explants and Drobnica 2 explants). Explants of Drobnica cultivars, which induced proliferation, were under the influence of cytokine treatment containing coconut water and first 3 days in the dark. Also on Rosulja cultivar, the proliferation-induced explants was spent 3 days in the dark. Coconut water in combination with BAP (50 ml/l + 0.5 ml/ l) has resulted in effective proliferation and further growth of explants. The release of phenolic components that are visible in the media, as well as some other harmful substances that are not visible to eye, lead to the death not only olive explants but also other strategically important fruit species on in vitro production. Further research needs to be focused to more precisely determine the various combinations of coconut water-based hormone concentrations, or adsorbents and methods in suppressing the accumulation of toxic harmful phenol substances