Otimização de protocolos para a propagação in vitro de gérbera (Gerbera jamesonii)

Abstract

Gerberas are cut flowers with large color diversity and good durability. The use of growth regulators on in vitro propagation is related to the capacity to induce proliferation of sprouts and differentiation of roots. However, citokinins in excess can induce the formation of abnormal plant, with reduced acclimatization potential. The mineral and organic composition of media culture plays an important role during the process. The objective of this dissertation was to adjust protocols for in vitro propagation of Gerbera jamesonii. The following aspects were evaluated: (i) the effect of the inflorescence developmental stage on the performance of in vitro culture initiated from chapters (ii) gerbera varieties (iii) growth regulator balance and (iv) the effect of salt concentration of MS medium on the proliferation of in vitro sprouting and rooting and acclimatization of three varieties of gerbera. For variety Phanter, the regeneration of explants prepared from inflorescences depended on its stage of development. Explants prepared from young chapters showed better results. The concentration and source of citokinin, and the concentration of salts in MS medium influenced the proliferation of sprouts in explants of variety Ornela. BAP was more efficient than kinetin on proliferation of sprouts. Concentrations above 2.0 mg.L-1 of BAP induced the formation of plants with undesirable characteristics during in vitro multiplication, while this was not observed in the presence of the same kinetin in larger concentration (4.0 mg.L-1). The combinations of 0.5 mg.L-1 BAP with the different levels of IBA showed the best results for multiplication and production of sprouts, with potential for acclimatizing variety Ornela. The presence of BAP inhibited the differentiation of roots, while the same was not observed in largest concentration of kinetin. The concentration of salts below 50% limited the proliferation of sprouts in variety Ornela. The varieties Capuccino, Mirage and Ornela, when maintained in the same balance of BAP and IBA, showed divergences in results for number of sprouts; when acclimatized, they presented high survival rates. Difficulties on in vitro gerbera propagation were mostly found on the regeneration phase and on the formation of sprouts in explants prepared from chapters. For the other phases, no major difficulties were detected.