nfluências de vitaminas no desenvolvimento e crescimento in vitro de Cattleyas brasileiras

Abstract

Vitamins belong to a group of organic nutrients. They are essential in small quantities to life performing several functions in the metabolism and as antioxidants or resistance inducers. The lack of vitamins may cause many developmental and metabolic problem, as well as the excess may also be toxic. However, the use of an appropriate dose is necessary. The limited number of studies on the topic relative to orchids justified the need for this work, which aimed to evaluate the influence of B vitamins, Thiamin (B1), Nicotinamide (B3) and Pyridoxine (B6) on the development and seedling growth of Cattleya labiata, Cattleya walkeriana and Cattleya brevicaulis during 120 days. The seeds were obtained from UNOESTE Orchid Seedbank. In the Tissue Culture Lab at UNOESTE the experiment was carried out in in vitro half strength MS medium for seedling growth; with the variations in the vitamins: 0.025; 0.05; 0.1 and 0.2 mg L-1 for Thiamine, and 0.125; 0.25; 0.5 and 1 mg L-1 for Pyridoxine and Nicotinamide. The increment in the fresh weight at each 30 days, dry weight at the end, shoot and root length and the number of shoots and roots parameters were evaluated. The assayed complex B vitamins, thiamine, nicotinamide and pyridoxine exhibited isolate effects in orchid seedling growth. It is recommended to reduce the thiamine dosage to 0.025 mg L-1, decrease the dosage of pyridoxine to 0.125 mg L-1, and do not add nicotinamide in any concentration in the medium.