Simplified Method for Rooting Apple Cultivars in Vitro

Abstract

Abstract Apple cultivar cuttings, prepared from shoots proliferated in vitro, initiated roots readily when placed for 3–7 days in the dark in a liquid medium containing only 43.8 m m sucrose and 1.5 μM indolebutyric acid (IBA). Raising the temperature during dark treatment from 25° to 30°C improved rooting for several cultivars. The addition of half-strength Murashige and Skoog (MS) salts or of phloroglucinol (PG) to the rooting medium did not improve rooting. IBA was the most effective auxin tried and indoleacetic acid (IAA) the least effective. Maintaining the cultures in the dark for more than 6 days improved rooting of only 1 cultivar and after 9 days rooting percentages sometimes decreased. More than 80% rooting was obtained with ‘McIntosh’ and ‘Mutsu’ after only 4 subcultures (4–5 months in culture), whereas some other cultivars in culture for a much longer time rooted no better or not as well. Roots that were initiated in liquid medium elongated after cuttings were inserted into preformed peat plugs. The resulting plantlets acclimated easily for transfer to greenhouse conditions.