The acquisition of potassium nitrate for any purpose, including preparation of nutritive media for micropropagation, depends on authorization from the Ministry of Defense, what turns out in difficulties in its acquisition. With the purpose of studying the possibility of replacing this component of the culture for another product found freely in the market, an experiment was carried out, where several concentrations of potassic saltpetre were tried, in comparison to the chemically pure potassium nitrate, as a component of the MS salts formulation. The commercial granulated product MURER® was used in the following (g L-1): a) 7,0; b) 7,4; c) 7,8; d) 8,2; and e) chemically pure potassium nitrate (control-treatment) as it appears in the MS salts, or 1,9 g L-1Fáfia was tested, starting from nodal segments. The basal nutrient medium comprised the MS salts, White vitamins, 30 g L-1 sucrose, 2.0 mg L-1 indol butyric acid, 2.0 mg L-1 naftaleneacetic acid, 2.0 mg L-1 benzilaminopurine, pH 6.0 + 0.1 and 1.5 g L-1 Phytagel® as the gelling agent. The number of branches formed in all concentrations of potassic saltpetre was lower than those ones in the control treatment; however, their lengths were higher. The mean length of branches in the treatment with the smallest potassic saltpetre concentration, reached 17.0 cm in length, while in the control-treatment it was 12,6 cm. The dry biomass weight reached 68.3 mg for the smallest potassic saltpetre concentration, but only 50,0 mg for the control treatment. The results indicated to be advantageous the substitution of the chemically pure potassium nitrate for the potassic saltpeter, when either shoot elongation or biomass production is desired, being the nutrient medium sterilized with sodium hipoclorite. However, when a faster multiplication rate is the main objective, the nutrient medium should be prepared with chemically pure potassium nitrate.
Pfaffia glomerata; micropropagation; minerals salts preparation; PA reagents
