EFFECTS OF PRETREATMENT TEMPERATURE AND CAP CLOSURE ON PHOTOSYNTHESISPOTENTIALITIES OF POTATO CULTIVATED IN-VITRO

Potato tubers, Solanum tuberosum L. cv. Bintje were stored at 4 or 20 degrees C. A segment of parenchyma with a bud was cultivated in vitro, in order to study the growth of plantlets according to the storage te mperature and the atmosphere composition in vessels. The conservation temperature had no effect on the shoot length, the leaf area and the l eaf number. On the other hand, the atmosphere composition in vessels m odified the morphology. The plantlets cultivated in non-sealed vessels were more developed than the plantlets cultivated in hermetically clo sed tubes. The photosynthetic potentials were 4.7 times higher for the plantlets coming from the tubers stored at 20 degrees C than for the plantlets coming from the tubers stored at 4 OC. These potentials were 1.7 times higher when the plantlets were cultivated in non-hermetical ly closed tubes than in hermetically closed ones. So a conservation of tubers at 20 degrees C and a culture in non-enclosed vessels seemed t o be the suitable conditions for the micropropagation of potatoes in v itro. Moreover, this culture type could improve the acclimatization.