EFFECTS OF TEMPERATURE AND HYPOXIC ATMOSPHERE ON PRESERVATION AND FURTHER DEVELOPMENT OF IN-VITRO SHOOTS OF PEACH (ARMKING) AND PEACH X ALMOND HYBRID (GF-677)

To improve planning of in vitro plant production and/or to preserve ge rmplasm, micropropagated shoots of peach ('Armking') and peach x almon d ('GF 677') were submitted to low oxygen concentrations (0.25-0.2%, p lus air as control) combined with decreasing temperatures (25-degrees- C, 12-degrees-C, 0-degrees-C). This method is frequently used in post- harvest physiology to slow down the senescence processes of organs. 'A rmking' shoots survived for at least 8 months and 'GF 677' for 10 mont hs at 0-degrees-C. At this temperature, hypoxic conditions had no effe ct on survival but enhanced regrowth of the shoots afterwards, leading to the maintenance of the multiplication rate. At 25-degrees-C and 12 -degrees-C, hypoxic regimes replaced low-temperature storage, but for shorter times: 2 months for 'Armking' and 4 months for 'GF 677' at 25- degrees-C and at least 4-6 months for the two genotypes at 12-degrees- C. This method should thus be used for in vitro preservation of cold-s usceptible plants. In addition, hypoxia increased shoot branching capa city, and could be used to promote in vitro micropropagation of specie s with strong apical dominance.