Mineral salts and growth regulators for micropropagation of Laelia halbingeriana Salazar & Soto Arenas

Abstract

Laelia halbingeriana Salazar & Soto Arenas is a wild epiphytic orchid endemic to Oaxaca, Mexico, that is collected with no plans for its management or conservation. The objective of this study was to propagate and evaluate the in vitro development of this species in the culture media with a variety of mineral salts and growth regulators. Groups of three plants, 1.2 to 1.4 cm tall, were established in receptacles with culture medium containing 30 g L -1 sucrose, 1 mg L -1 thiamine, 100 mg L -1 inositol and 0.5 mg L -1 benzyl aminopurine (BAP). Proportions of Murashige and Skoog (1962) or Knudson (1946) mineral salts were varied (100, 66 and 33%). The growth regulators indoleacetic acid (IAA) and kinetin (Kin) were used at various concentrations (0.5 + 0.5 mg L -1 , 1 + 1 mg L -1 and 2 + 2 mg L -1 ). pH was adjusted to 5.8, and 5.5 g L -1 agar was added. After 120 days of incubation, the plants that were cultivated in 66% and 100% Knudson media were 2.1 cm tall and had 4.8 roots, while the plants in 100% Murashige and Skoog media were 1.5 cm tall and had 2.5 roots. For 120 days, the plants had a logarithmic trend in vertical growth (R 2 ≥0.96). Several plant characteristics were evaluated simultaneously using a cluster analysis, which found that the best culture medium for Laelia halbingeriana development contains 100% Knudson mineral salts, 0.5 mg L -1 BAP, 0.5 mg L -1 IAA, and 0.5 mg L -1 KIN.