THE EFFECTS OF SEVERAL VARIABLES ON SHOOT-TIP GRAFTING OF "CLEMENTINE" MANDARIN ONTO "TROYER" CITRANGE

"Clementineʹ mandarin was successfully micrografted onto "Troyer" citrange [Citrus sinensis Osbeck X Poncirus trifotiata (L.) Raf.] rootstock in vitro. Shoot-tip grafted plants were transferred from culture tubes to greenhouse conditions by regrafting onto rough lemon seedlings. The effects of different closures of culture tubes on growth of seedlings were examined. The results showed that ʹTroyerʹ seedlings in culture tubes with rubber caps did not grow after seed germination, while seed germination and seedling growth with other closures took place normally. The effects of several variables on the micrografting success were also evaluated. When different concentrations of sodium hypochforite were examined for shoot-tip sterilization, the best result was obtained with the concentration of 0.1% of this sterilizer. Pre-treatment of scions by different concentrations of 2,4-D and kinetin did not affect the grafting success rate. Similarly, the application of different concentrations of GA3 or kinetin on quiescent scion tips did not induce seedling elongation. The highest rate of success (70%) was obtained when the concentrations of thiamine-HCI, pyridoxin-HCI and nicotinic acid were 14 times that of their recommended concentrations. The presence of light for scion survival was necessary and the lowest rate of lost scions (18%) was observed under 1500 lux illumination by cool white fluorescent lamps.