Desinfestação de segmentos nodais de mini-rosa (Rosa sp.) para o estabelecimento in vitro

Abstract

Brazil stands out as one of the largest producers of ornamental plants in the world, with the mini-roses (Rosa sp.) Becoming one of the best-selling potted flowers. However, in spite of the great economic importance of mini-roses, there is a lack of general research on mini-roses, mainly in the area of tissue culture. Generally, these plants are multiplied by vegetative propagation through cuttings, plunging or grafting. However, these traditional propagation methods have numerous undesirable characteristics, as they favor the spread of diseases and pests, seasonal dependence and low multiplication rate. Due to this problem, the objective of the work was to develop a disinfestation protocol for the in vitro establishment of mini-roses in which nodal segments containing axillary buds were used as source of explants. In a laminar flow hood, disinfestation was performed using 70% alcohol for 5 minutes, followed by immersion in commercial sodium hypochlorite with different concentrations of active chlorine (0.75%, 1.00% and 1.25%), with (10, 20 and 30 minutes) for each concentration. A total of 180 explants were inoculated in MS medium supplemented with 30 g / L sucrose. The experimental design was completely randomized in factorial 3 x 3 with 9 treatments and 5 replicates, containing 4 explants per plot. The variables variables of contamination, survival, necrosis, callus, number of responsive explants, number and height of the seedlings and number of leaves were evaluated. Among the treatments, the best results were the concentration of 1.25% with the immersion time of 30 minutes, resulting in a rate of disinfestation of 45%, which provided better conditions for in vitro establishment and development of segments nodal of mini-roses, showing a greater number and height of shoots and without formation of necrosis in the tissues. However, treatments with concentrations of 0.75% and 1% in the exposure time of 10 minutes were not efficient for disinfestation of the nodal segments, presenting a contamination rate of 100% and 90%, respectively, in the first evaluation days. Therefore, the concentration of 1.25% sodium hypochlorite associated with the 30-minute exposure time to the agent resulted in a higher aseptic rate of the mini-roses nodal segments, as well as higher survival and lower occurrence of necrosis explants, further providing the best conditions for in vitro establishment and development of nodal segments of mini roses. It should be noted that the disinfestation index of the explants was satisfactory, since the matrix plant used came from the field and did not undergo an aseptic pretreatment.