The effect of growth regulators on micropropagatin of GF677 rootstock under liquid mediumconditions

GF667 is a hybrid of Prunus Amygdalus × Prunus persica and is the most commonly used rootstock for peach, nectarines and almonds. Due to low efficiency of propagation trough cutting, tissue culture is a good and fast method for propagation of GF667. In the liquid medium, contact between the plant tissue and the medium is better, propagation is accelerated, and cost of production is reduced. Therefore, the aim of this study was to optimize micropropagation methods for GF677 rootstock by using liquid culture system.

In this study, sterile nodal explants were cultured on different media include Murashige and SKoog (MS), Woody plant medium (WPM) and Gamborg (B5) supplemented with various concentrations of BA (benzyl adenine) at concentrations of 0.25, 0.5, 1, 2 and 4 mg/L and IBA (indole-3-butyric acid) at concentrations of 0, 0.1, 0.25 and 0.5 mg/L. Elongated shoots of GF677 were cultured on MS medium supplemented with 0.25, 0.5, 1.0 and 2.0 mg/l IBA and 0.0, 0.1, 0.2 and 0.5 mg/l BA for rooting. Factorial analysis of variance was carried out and differences between means were scored with LSD tests.

Effect of different culture media (MS, B5 and WPM) and growth regulators (BA and IBA) on number of shoots per proliferated explant of GF-677 showed that the maximum number of shoots (2.44 shoots) was obtained in WPM medium at a concentration of 1 mg / l BA and the highest shoot length was obtained with 1 mg / l BA and 0.25 mg / l IBA in medium B5. As concentration of BA increased to 1 mg/l, the number of shoot also increased. It sounds that there is a positive correlation between concentration of BA and number of shoot to a certain concentration of BA, so that number of shoot reaches its peak at concentration of 1 mg/l BA. At concentrations higher than 1 mg/l BA decrease in number of shoots can be seen. It shows that when concentration of BA was in excessive amount, it resulted in decrease of shoot number. One of the possible reason can be reductive effect of higher concentrations of BA. Apparently a certain amount of BA is required to obtain the best effect. Higher concentrations of BA brought about formation of high amount of callus which is not appropriate in tissue culture. On MS medium containing 1.0 mg/L IBA and 0.5 mg/l BA, a maximum rooting efficiency was obtained. Rooted plants were transferred in terrestrial environments combination of perlite, sand and soil in the ratio of 1: 2: 1 respectively. Rooted plantlets were successfully acclimatized and transferred to potting mix with 90% survival and grow naturally after strengthening and transferred to soil.

The shoot multiplication of GF677 was influenced by the media (MS, B5 and WPM) and growth regulators. The WPM medium at a concentration of 1 mg/l BA gave the best results (2.44 shoots) for the proliferation of cultures from explant among the tested media.