Different types of explants and natural ventilation systems influence the accumulation of dry weight and of total phenolic compounds in Aloysia gratissima (Verbenaceae)

The objective of this study was to evaluate the effect of the use of different natural ventilation systems on the growth and accumulation of total phenolic compounds in Aloysia gratissima. Nodal and apical segments with 1 pair of leaves were inoculated in flasks containing ½ MS culture medium without sucrose and supplemented with 0.1 mg L-1 indole-butyric acid. The cultivation systems included a conventional system (NMS) and alternative membrane systems with 1 (AMS1), 2 (AMS2) and 4 (AMS4) low-cost membranes. After 30 days, the in vitro growth, leaf area, dry weight and accumulation of phenolic compounds were evaluated. Plantlets from apical segments showed superior results in all variables analyzed. The use of the NMS compromised plantlet growth. However, improved results were obtained with the use of porous membranes, with the best growth observed in AMS4. The leaf area of plantlets originating from apical segments was 3.03 times greater than that of plantlets from nodal segments. Plantlets in the NMS had the lowest values of leaf area, root length, number of leaves and dry weight. However, the use of membranes allowed higher growth. The AMS4 treatment increased the leaf dry weight accumulation by 6.13-fold compared to that obtained with the NMS treatment. The accumulation of total phenolic compounds increased with the use of greater numbers of porous membranes. The use of apical segments and lids with 4 porous membranes is recommended for micropropagation of the species. The use of an alternative membrane system positively influences the accumulation of total phenolic compounds.