FACTORS AFFECTING IN VITRO PROPAGATION OF THE PEACH-ALMOND HYBRIDS "HANSEN 2168 ®" AND "HANSEN 536 ® "

Cultures were established from actively growing shoot tips on Murashige and Skoog (MS) medium supplemented with 0.1 mg 1^-1 indolebutyrric acid (IBA) and benzylaminopurine (BAP) at different concentrations. A concentration of 1 mg 1^-1 BAP gave the best establishment. BAP at 0.6 – 1 mg 1^-1 promoted shoot proliferation whereas 2iP and kinetin promoted only growth of single shoots.

A temperature of 20°C and soft gelled medium (4.5 g l^-1 Riedel agar) were critical in order to avoid vitrification and ageing of the cultures.

A prerooting phase of 10 days in a stationary liquid double strength MS medium supplemented with 1 g 1^-1 Ca(NO₃)₂. 4H₂O proved to be very important to obtain good shoots for the rooting phase.

Rooting of over 90% of the shoots was achieved with half strength Lepoivre salts and 1 mg 1^-1 IBA. Some yellowing of the tips during rooting was overcome by adding 0.003 mg 1^-1 kinetin and 1 mg 1^-1 Ca (NO₃)₂.4H₂O to the medium.

Acclimatization in a glasshouse was satisfactory using a 4:1 peat: perlite mixture. Hundreds of thousands of plantlets were produced this way during spring and summer 1984.