Aspects Regarding the In Vitro Culture and Ex Vitro Rooting in Vaccinium macrocarpon Cultivar 'Pilgrim'

Abstract

Our paper presents aspects regarding in vitro culture initiation in cranberry ( Vaccinium macrocarpon ), cultivar `Pilgrim`, in vitro multiplication and ex vitro acclimation. In order to establish the optimal explant for initiation, several types of explants: single node fragments without leaves, single node fragments with leaves, two-node fragments without leaves, two-node fragments with leaves, multiple node fragments (3-4 nodes with leaves) and 1-1.5 cm long shoot tips were tested on media of the same composition (modified Woody Plant Medium). After testing the explant types, three variants of nutritive media were tested: WPM with three concentrations of 2-Isopentenyladenine: 5, 10 and 20 mg/l in order to induce the proliferation of axillary buds in the initiation phase. In the multiplication phase, several types of culture vessels were tested, as well as the optimal number of inocula/vessel and the influence of growth regulators upon multiplication rate. Among the variants of nutritive media that were tested, modified WPM containing either 1 mg/l zeatin or 5 mg/l 2-Ip presented reasonable proliferation rates and relatively well-developed shoots. In the in vitro layering experiment, 2-Ip at 10 mg/l generated tens of thin shoots/explant. As gelling agents, starch and Plant Agar were tested. Ex vitro acclimation was carried out in Jiffy7 pellets in either covered or uncovered plastic trays and various survival rates (17-92 %) were obtained depending on explant types and culture conditions.