Micropropagation of Difficult-to-Propagate Almond (Prunus Amygdalus, Batsch) Cultivar

Abstract

Summary An in vitro culture scheme has been developed which allows rapid clonal multiplication of shoots starting with excised shoot apexes (0.4-0.7 mm) from flushing buds of a “difficult-to-root” almond cultivar, “Ferragnes”. Up to 55% of these shoots could then be rooted in vitro for establishment in the soil. After an initial 3–4 subcultures on media allowing slow-growth, shoots were placed on Murashige and Skoog (MS) medium with 0.9% agar, 0.7 mg/l 6-benzylaminopurine (BAP) and 0.01 mg/l α-naphthaleneacetic acid (NAA). Shoot multiplication rates of six could be obtained with 20-day periods of subculture continued for at least 24 months. At any points these shoots could be elongated by placing them on identical medium, lowering the BAP (0.2 mg/l) and omitting NAA. Each shoot was then reduced to 2-3 leaf microcuttings for rooting tests. Rooting was induced quickly in the dark in about 55% of the microcuttings using the medium of Bourgin and Nitsch (BN) with only the macronutrients reduced to half, but containing 0.9% agar and 1 mg/l NAA or 1 mg/l γ-(indole-3)-butyric acid (IBA). Further proliferation of roots was successfully achieved in the liquid medium in the absence of any added auxin; sterile vermiculite served as the support. Some plants have been established in the soil.