Germinação, organogênese e multiplicação in vitro de Campomanesia adamantium (Myrtaceae)

Abstract

The development of efficient asexual propagation techniques of ‘guavira’ (Campomanesia adamantium) has fundamental importance for the species conservation, considering the limitations found in the seminiferous propagation, imposed by the recalcitrance and loss of seeds germination power. In this sense, in vitro culture techniques may contribute to the production of seedlings. In order to develop protocols for in vitro culture of this species, this work was carried out in three stages. Initially, the in vitro germination was analyzed basing on seeds from different fruits collection sites, storage conditions of seeds and temperature, as well as inoculation in MS medium, supplemented with different concentrations of gibberellic acid (GA3). In the second stage, it was evaluated the in vitro organogenic capacity, from leaf, root and internodal explants and the effect of growth regulators, TDZ and NAA. In the third stage, in vitro multiplication of capacity was evaluated using as a source of explants seedlings obtained from seeds germinated in vitro and subjected to different treatments with TDZ, NAA, BAP and 2iP. According to the data obtained in different experiments, it was concluded that in guavira seed inoculated in culture medium immediately after harvest, the use of GA3 promotes an increase of 10% of the germination percentage, with the use of 1,0 mg L-1 enough to promote 100% germination. The aerial part length increases linearly with increasing concentration of GA3, but has no effect on the development of the primary root and leaves. Seeds acquired from free fair fruits have a germination percentage lower than the inoculated seeds after harvesting the fruit and do not differ as to the percentage of germination under different treatments with GA3. Germination is not feasible in ‘guavira’ seeds stored at different temperatures (4°C and -20°C) and in different places (refrigerator and freezer) for 60 days, being not possible the conservation of seeds in these conditions. In turn, the storage at room temperature (±25°C) causes premature germination. As the organogenic capacity, it was concluded that are more responsive internodal explants for callus formation (84%), when compared to leaf explants (69%) and root explants (42.7%). Intermodal explants do not show corrosion, this variable being observed at greater intensity of leaf explants (41%), followed by 14.7% of root explants. For in vitro mutiplication, the results demonstrated that the use of 5.0 μM TDZ increases the length of shoots, the number of buds and the multiplication rate, while the combination of TDZ and NAA has a negative effect on growth of shoots, number of leaves and the multiplication rate. The explant culture in medium containing BAP increases the number of shoots in proportion to the increased concentration of growth regulator, however, the other way reduces the length of the shoots. Explants cultured in medium containing 2iP, to the variables analyzed, did not show significant differences between the tested concentrations.