Effects of plant growth regulators and sucrose on the regeneration of Paphiopedilum micranthum var. North Vietnam

Abstract

The objective of this study was to determine the effects of 2,4-Dichlorophenoxyacetic acid (2,4-D) combined with 6-Benzylaminopurine (BAP) and sucrose on the shoot and root regeneration of Paph. micranthum var. North Vietnam. Young fresh leaves were cut into small explants and then cultured on media containing 2,4-D (0.5, 1.0, or 2.0 ppm). Within each of the 2,4-D concentration, BAP was added at three different concentrations (0.5, 1.0, or 2.0 ppm) for callus induction after 4 weeks. Shoot tips (2-3 mm in length) from the leaf-derived calluses were then transferred vertically on half-strength MS medium (2,4-D combined with BAP (0.5, 1.0, or 2.0 ppm) for shooting, and rootless shoots with 2 leaves were transferred to the same MS medium for rooting after 4 months of culture. Rootless shoots with 2 leaves were also transferred vertically on half-strength MS medium with different sucrose concentrations (0, 10, 20, 30, or 40 g L-1) to optimize the growth and development of the plantlets. The results indicated that the optimum degree of shoot and root regeneration occurred on half-strength MS medium containing 2.0 ppm 2,4-D combined with 2.0 ppm BAP. Approximately 86.6% of the cultures responded with 3.3 shoots and 3.0 leaves/explant. In addition, under the optimal concentrations, the number and length of roots per explant after 4 months of culture were 2.1 roots per explant and an average root length of 1.1 cm. MS medium supplemented with 30 g L-1 sucrose had the highest number of leaves and roots, and also the longest average length of roots, which gave 3.8 leaves, 3.3 roots/explant, and a root length of 1.8 cm after 4 months.