Potassium, calcium and magnesium in tropical ornamental plants micropropagation.
Considering the increase in economical importance of species belong to Zingiberaceae family for floriculture and the advantages of techniques applied to micropropagation of these plants, it is necessary to carry out studies about growth of species in these conditions. The aim of this study was to evaluate the in vitro development of Etlingera elatior, Zingiber spectabile and Alpinia purpurata under different ratios of K, Ca and Mg. The treatments were based on MS medium with K: Mg ratios (mmol L-1) of: 22 K:1 Mg, 20 K:3 Mg, 16 K:7 Mg, 12 K:11 Mg, 8 K:15 Mg 4 K:19 Mg; K:Ca ratios (mmol L-1) of: 22 K:4 Ca, 20 K:6 Ca, 16 K:10 Ca, 12 K:14 Ca, 8 K:16 Ca and 4 K:22 Ca; with five replications, and two seedlings per pot. Explants used were obtained from in vitro rhizomes, kept in a room at a temperature of 25±2°C under irradiance 52 W m-2 s-1 and 16 hours photoperiod. After 80 days, seedlings were harvest and have the about number of leaves, height and length of root measured. After, seedlings were separated in shoots and roots, dried and carried out chemical analysis of plant tissue. It is possible to improve the Zingiberaceae plants growth during the micropropagation, changing the concentrations of original formulation MS medium. For K are recommended concentrations of 22 mmol L-1 to Etlingera elatior and Zingiber spectabile cultivation and 16 mmol L-1 for Alpinia purpurata. For Ca, we recommend the concentrations of 4 mmol L-1 for Etlingera elatior and Zingiber spectabile and from 8 to 10 mmol L-1 for Alpinia purpurata. A higher concentration of Mg for in vitro cultivation Etlingera elatior is required. For Zingiber spectabile and Alpinia purpurata it was recommended the proposed merger among MS original concentration of 3 mmol L-1 of this macronutrient.