Abstract
An in vitro cloning protocol that enables shoot proliferation and rooting of cranberry (Vaccinium macrocarpon Ait.) genotypes in the same medium was developed. Plantlets of four clones (NC197, NC201, NC216, and NC230) from natural stands in Newfoundland and Labrador and one cultivar, Stevens, were obtained in vitro from nodal explants on a nutrient medium containing the plant growth regulators, N6-[2-isopentenyl]adenine (2iP) or zeatin. Zeatin was more effective than 2iP for shoot proliferation and rooting. The genotypes differed in terms of shoot and root number per explant, length and vigor, number of leaves per shoot, and callus formation at the base of explants; this was manifested with various concentrations of 2iP and zeatin over two culture periods. Shoots proliferated and roots developed best when nodal segments were cultured in the medium supplemented with 2 μM to 4 μM zeatin. Subculturing improved the number of shoots and roots per responding explant, shoot height, root length, and root vigor. Changing the positioning of explants on the medium from vertically upright to horizontal increased shoot number and callus size, but decreased the rooting incidence, roots per explant, and root vigor. The protocol proposed from this study is expected to be applicable for propagating a wide range of cranberry germplasm.
