Aspects of medium-term in vitro storage of raspberry varieties (Rubus idaeus L.)

Abstract

The study aims to optimize the procedure for storing 12 varieties of Rubus idaeus L. of different fruiting types. The experiment used 1/2 Murashige and Skoog (MS) medium supplemented with agar (6.8 g/L), sucrose (20 g/L), and 6-benzylaminopurine (0.3 mg/L). The effects of temperature (+23 ℃ and +15 ℃) were examined, as well as that of a retardant, chlorocholine chloride at 0.2 g/L (CCC), used as part of the nutrient medium. A high percentage of viable explants (48.7- 73.0 %) was found to survive up to nine months under different cold storage conditions. From month 9 to month 12, the percentage of viable explants decreased (by 1.3-2.1 times depending on storage conditions). It was found optimal to store the studied varieties of R. idaeus in vitro at a lower temperature (+15℃) on 1/2 MS medium supplemented with 0.3 mg/L of 6-benzylaminopurine without the addition of a growth inhibitor. After 12 months of storage, the percentage of viable explants amounted to 56.9. The growth percentage of viable explants after in vitro storage at +15 ℃ on media without CCC amounted to 98.6, with an average propagation factor of 5.6, number of microshoots of 2.7 pcs./explant, and microshoot length of 1.3 cm. The presence of CCC in the medium was noted to reduce the growth rate of explants, while adversely affecting the percentage of viable explants. Thus, after 12 months of in vitro storage at +15 ℃ on media with the addition of CCC, the percentage of viable explants amounted to 39.2 %. It was noted that from month 3 to month 12 of storage at +15 ℃ on nutrient media with the addition of CCC, the number of microshoots and their length changed insignificantly (by 1.2 and 2.6 times), as compared to the indicators of microshoots cultivated in a grow room (by 1.8 and 3.3 times). The development of explants of the studied R. idaeus genotypes after in vitro storage was found to be affected by the type of fruiting and varietal features of the crop.