Adventitious root and shoot regeneration in cultured explants of mature black spruce

Abstract

Embyronic shoots with crown excised from vegetative buds of 15–35-year-old black spruce [ Picea mariana (Mill.) B.S.P. were induced to form adventitious roots from either the cortex at the shoot base or the axillary region of leaf primordia. The roots were initiated in one-half-strength Gresshoff and Doy (Planta, 107 (1972) 161) medium after the embryoic shoots had been cultured on the medium supplemented with 2,4-dichlorophenoxyacetic acid and naphthaleneacetic acid for 4 weeks or less. Prolonged incubation on the medium with growth regulators resulted in differentiation of adventitious roots on leaf primordia. Formation of adventitious shoots occured when embryonic shoots were cultured on one half or full strength Gresshoff and Doy medium supplemented with benzylaminopurine and naphthaleneacetic acid for 4 weeks or less before being transferred onto the respective medium without any growth regulators. Adventitious shoots often differentiated from the axillary region of leaf primordia on the embryonic shoots. Some leaf primordia differentiated directly into adventitious shoots and others produced calli before differentiation of the shoots. Culture on the medium with growth regulators for more than 4 weeks increased callus formation and decreased adventitious shoot regeneration on embryonic-shoots.