Selection of alternative agents to agar for the propagation of <i>Cattleya loddigesii</i> (Orchidaceae) plantlet

Abstract

The aim of this study was to evaluate the in vitro growth of Cattleya loddigesii in alternative agents to agar with starch and physical matrix with  acclimatization of regenerated plants. Protocorms with 90 days after sowing (0.5 cm of length) were subcultured in ½ MS culture medium among the  treatments consisting of: agar 7 g L^-1 (T1, which corresponds the control), agar 3,5 g L^-1 with cassava starch 30 g L^-1 (T2), cassava starch 60 g L^-1 (T3), cotton fiber (T4) and chopped polyurethane foam (T5). Plantlets were retained in these treatments for over 150 days, and at the end of in vitro culture, were analyzed by their biometric data and acclimatized in a greenhouse during 120 days and evaluated the survival and relative growth rate (RGR). The substrate  comprising of chopped polyurethane foam (T5) showed greater efficiency for growth in vitro and also increased survival rate, while substrate cassava starch (T3) provided delay for plantlet growth. Therefore, chopped polyurethane foam is recommended because of low cost and suitable characteristics for the propagation of Cattleya loddigesii.