Concentrações de sais do meio Knudson C e de ácido giberélico no crescimento in vitro de plântulas de orquídea

Abstract

The aim of this research was to test different concentrations of culture medium Knudson C and gibberellic acid in the in vitro growth of Hadrolaelia lobatta x Hadrolaelia purpurata Aço and Cattleya loddigesii plantlets. Seedlings deriving from in vitro germinated seeds with approximately 1,0cm length, were inoculated in bottles of 250cm3 containing 60mL of Knudson C culture medium at salts concentrations of 0; 50; 100 e 200%, and supplemented with 0; 2.5; 5; 7.5; 10mg L-1 of GA3. The cultures were maintained in growth room with a 35µmolm-2s-1 irradiance, 16 hours photoperiod and 25±1°C of temperature. After 90 days, it is observed that the culture medium Knudson C 200% for Cattleya loddigesii promote better in vitro growth. The addition of GA3 (2.5mg L-1) is efficient in the number of leaves increment. Better in vitro multiplication is registered in Knudson C medium in the original concentration (100%). For Hadrolaelia lobatta x Hadrolaelia purpurata Aço, the concentration of Knudson C culture medium influences the number of leaves (salts 200%) and sprouts (salts 50%), but does not have effect in the growth and biomass. No effect of the GA3 in number of sprouts, length of aerial part and fresh mass for the two genotypes was verified.