In vitro and ex vitro growth of grapevine rootstock '5BB' as influenced by number of air exchanges and the presence or absence of sucrose in culture media

Abstract

Single node cuttings of grapevine rootstock `5BB' were cultured for 5 weeks under different numbers of air exchange (0, 0.8, 1.5, 2.5 and 4.4 h −1) with or without sucrose in the medium. To determine the effect of number of air exchanges related to presence or absence of sucrose, in vitro growth, net photosynthetic rate, stomata characteristics and ex vitro growth were investigated. Increasing numbers of air exchanges accelerated plantlet growth regardless of the presence or absence of sucrose in the medium; under the same number of air exchanges, plantlet growth and net photosynthesis were greater in sucrose-containing medium compared with sucrose-free medium. However, a high number of air exchanges (4.4 h−1) inhibited the growth and photosynthesis in sucrose-containing medium compared to sucrose-free medium. A higher number of stomata was observed in sucrose-containing medium, and larger size stomata was observed in sucrose-free medium. These results emphasize the importance of ventilation (increased number of air exchanges) during in vitro culture, for ex vitro plantlet survival was greatly affected by with or without air exchanges. Without air exchanges ex vitro plantlet survival was less than 70%, while air exchanges increased ex vitro survival by more than 90% with greater growth.