Improved in vitro development of Epidendrum secundum (Orchidaceae) by using aqueous extract of the seaweed Kappaphycus alvarezii (Rhodophyta, Solieriaceae)

Abstract

Orchidaceae is one of the largest plant families and includes species with high economic, ecological, and medicinal importance. Orchid seeds are produced in high amounts; however, these seeds show low germination percentage and have specific germination requirements. To enhance the germination and development of orchids, in vitro techniques have been successfully applied. Natural extracts can be used as a biostimulant in the culture medium, showing improved germination, elongation, and rooting. Thus, the main objective of this study was to determine the effects of Kappaphycus alvarezii aqueous extract in the in vitro development of Epidendrum secundum, evaluating its influence on plantlet morphoanatomy. The K. alvarezii extract was also characterized by nuclear magnetic resonance (NMR) spectroscopy. E. secundum plantlets obtained after the in vitro germination were subjected to in vitro elongation experiment in the presence of K. alvarezii extract (0, 6, 12, 25, 50, and 100 mg L− 1). Our results indicated that the aqueous extract of K. alvarezii has a positive effect, stimulating rooting, plantlet development, fresh mass gain, and newly formed shoots of E. secundum plantlets, mainly at 50 mg L− 1 concentration. The use of K. alvarezii extract indicates potential application in tissue culture and plant production, due to its biostimulating effect on plants. Considering the great market demand for new technologies and the growing interest in the application of marine resources, our results present relevant data on the biostimulating potential of this extract, which can be successfully applied for the cultivation of other species of orchids and species of ecological and economic interest.