Cultivo in vitro e criopreservação de sementes de gergelim (Sesamum indicum L.).

Abstract

The sesame (Sesamum indicum L.) originating from Asia, it has been cultivated in the northeast of Brasil since 1986, being found in the states of Ceara, Rio Grande do Norte and Paraiba. Considering the economic importance mat the species represents for the Brazilian northeastern semi-arid region, the main objective of the first chapter of this study was based upon studying methods to make possible its multiplication in large scale through the "in vitron" cultivation: the study began with material derived from inoculated seeds in a MS basic environment, after its aseptic treatment. It was also carried out a seed pre-treatment that consisted on the use of the a MS+BAP (8mg.L'') environment for 72 hours so that it could be used on the induction attempts to organogenesis, that were evaluated through the entirely casualized outling, with a fatorial arrangment of 3x2x4 (3 varieties x 2 pre-treatment and 4 growing regulators). The statistical analyses were carried out using the Assistat computacional program. Still in the usage of induction attempts to organogenesis, now to obtain calogenesis, on the purpose of evaluate the growing regulators in the development of embryonic callus, the computational program Origin 5.0 was used for the data statistical analysis. According to the results obtained we concluded that: regarding to the seeds assepsy: a) the CNPA-G2 variety was superior to all of them presenting the largest germination rates and energy not being different from witness; b) the sesame seeds assepsy, CNPA-G2 variety can be done unith the sodium hipoclorite concentration varying from 10 to 40%. through 10% is the most economic one. The germitest paper (GP) is recommended for the germination; c) the hipoclorite concentration to be recommended to do the sesame seeds CNPA-G3 variety is 20% and the best environment to induce the seed germination is the germitest paper (GP); d) regarding to the sesame seeds assepsy, Serido-l variety, the sodium hipoclorite concentration that causes less damages to the seeds is in the rate of 20% and the cultivation environment recommended is the MS one: e) regarding to ten fitopatological analysis, we conclude that the fungi found were Aspergillus sp, Penicillium spp, Rhizoctonia and Rhizopus sp. with Serido-l variety presenting biggest incidence of contamination among them high lighting the biggest presence of Aspergillus sp. in all varieties. The CNPA-G3 variety, however, was the one that presented the smallest incidence of fungi. Regarding to the process carried out "with" and "without" seeds pre-treatment induction to organogenesis we concluded that: a) when the seed pre-treatment was carried out, there was a biggest incidence of buds /living explants; b) on the calogenesis induction occurred bigger formation of callus in the MS environment, when it was supplemented the growing regulators BAP and NAA to all sesame varieties. On chapler II of this work, it was suggested the initial determination of humidity limit to cryopreservation (HTLC) and after it was carried out the evaluation of sesame varieties, based on the germination and energy, subjected to the - 196°C cryopreservation temperature, using 3 cryoprotectos (Crioprotector 1- polyethilene tube; Crioproteetor 2- aluminium envelope and Cryiprotector 3 Com starch), two techniques at defrosting (environmental temperature and thermostatic bathe (40°C)) and 3 storage periods (5, 30 and 60 days). The experimental underlining used in this step was intirely casual with fatorial arrangment of 3x2x3 (3 varieties x 2 methods of defrosting x 4 storage periods). According to the results obtained we can concluded mat when you study the determination of the humidity limit tenor to cryopreservation - HLTC, during 5 days it is stated that: a) the humidity tenor to cryopreservation of Serido-l sesame, CNPA-G2 and CNPA-G3 is about 6% (b.u), presenting a gennination rate ot 90% and energy between 17 and 24%; b) the sesame seed variety CNPA-G3 shows a better adaptation to cryopreservation immerse in liquid nitrogen (-196°C); c) for the cryopreservation of variety CNPA-G3 we can use humidity tenor between 6 and 8% (b.u). Both the germination and energy of the seeds won't be affected Regarding to the seeds cryopreservation of we can state that: a) the best rates of gennination and energy for Serido-l and CNPAG2 were obtained when the seeds were defrosted at environmental temperature. The variety CNPA-G3, however, presented a better rate of energy when the seeds were defrosted at 40°C in a thermostatic bathe; b) it was obtained better rates of germanation and energy when he varieties were cryopreserved using as cryoprotector the almninium envelope, c) the increasing of germination and energy rates were obtained when the sesame seeds were cryopreserved on a 60 day storage period in comparison with period on a 5 and 30 days.