Natural ventilation and sucrose concentrations in the in vitro culture system affect the acclimatization of "Pérola" pineapple plants under different substrates

Plant tissue cultures represent a powerful set of tools that can be used in the production of pineapple seedlings. However, few studies have assessed the morphophysiological performance during the ex vitro acclimatization stage. Here, we evaluated the effect of different in vitro cultivation systems with sucrose reduction and types of flask sealing (without or with natural ventilation), as well as contrasting substrates on the growth and development of pineapple plants (Ananas comosus cv. Pérola) during ex vitro acclimatization. A randomized design in a 3 × 2 factorial was used with three in vitro cultivation systems [photomixotrophic (PM) + 30 g L-1 sucrose; photomixotrophic with natural ventilation (PNV) + 10 g L-1 sucrose; and PNV + 30 g L-1 sucrose)] and two ex vitro substrates (non-commercial and commercial). Our results showed that the commercial ex vitro substrate increased the height, stem diameter, and dry mass of aerial parts of plants by 25%, 14%, and 40%, respectively. Plants in PNV + 10 g L-1 sucrose and PNV + 30 g L-1 sucrose culture systems displayed reductions of 31% and 44% in respiratory rate, respectively. Notably, plants in a PNV + 10 g L-1 sucrose culture system displayed significant reductions of 36% and 41% for stomatal conductance to water vapor and transpiration rate, respectively. Thus, "Pérola" pineapple plants grown in a PNV + 10 g L-1 sucrose culture system using a commercial substrate exhibited improved gas exchange, with greater plant growth and development during acclimatization