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Setotaw T.A.,Agricultural Research Agency of Minas Gerais EPAMIG | Nunes C.F.,Agricultural Research Agency of Minas Gerais EPAMIG | Nunes C.F.,Instituto Capixaba Of Pesquisa | de Souza C.S.,Agricultural Research Agency of Minas Gerais EPAMIG | And 7 more authors.
Australian Journal of Crop Science | Year: 2015

Aluminum toxicity is a major agricultural problem at low pH that inhibits the root growth and plant development. Therefore, selecting cultivars with Aluminum (Al) tolerance will be crucial step for the breeding programs. This work was done with the objective of evaluating the Al tolerance of six principal olive genotypes: 'MGSASC315'; 'Barnea'; 'Leccine'; 'CLO0025'; 'Coratina' and 'Mission' based on relative root growth, organic acid exudation, and root apex hematoxylin staining analysis. For root growth and hematoxylin staining, the experiment was laid on 4 × 6 factorial (4 doses of AlCl3 (0, 250, 500 and 1000 μM), 6 genotypes of olive) in hydroponic solution under greenhouse condition. The root growth was measured for five consecutive weeks in a week interval. The organic acid exudation was evaluated after 24 and 48h exposure for Al in solution containing 0, 100, 200 and 400 μM of AlCl3. The 1000 μM of AlCl3 severely inhibited the root development of olive genotypes while 250 and 500 μM AlCl3 produced small damage when compared to plantlets grown in the control solution. The analysis of organic acid exudation after 24 and 48h exposure to Al3+ showed citric acid involved on Al tolerance mechanism in olive, whereas malate and oxalic acid did not. Among the olive genotypes MGSASC315, Barnea and Leccine recorded high relative root growth and high citric acid exudation under Al stress that showed these genotypes are tolerant for Aluminum stress. The result also showed hematoxylin staining of the root apex of olive tree was not efficient in discriminating among control, 250 and 500 μM AlCl3 treatments within each genotype.

Nunes C.F.,Federal University of Lavras | Santos D.N.,Federal University of Lavras | Pasqual M.,Federal University of Lavras | Teixeira Valente T.C.,Federal University of Lavras | And 3 more authors.
Australian Journal of Crop Science | Year: 2013

The successful regeneration of Jatropha curcas requires easily reproducible methods. Therefore, this study was undertaken to evaluate the effects of sources of explants, growth regulators, coconut water, nitrogen and flask sealing on the quality and quantity of shoots derived from leaf segments of Jatropha curcas after in vitro manipulation. The highest morphogenetic responses, 4.8 and 4.56 (numbers of adventitious shoots), were obtained from leaf cotyledon plantlets cultured in half-strength MS medium in the presence of BAP separately or combined with IAA (at a concentration of 4.4 μM of BAP + 2.8 μM of IAA). Enhanced shoot multiplication rates of 2.07 and 1.84 were observed in MS medium without coconut water and with the flask sealed with plastic film or a polypropylene lid with a filter, respectively. This result demonstrated the positive effects of minimum air circulation between the internal and external environments of the culture medium during regeneration. Concentrations of KNO3 and NH4NO3 between 50 to 100 % in MS medium favored the induction of callus and shoot formation at the 60th day of culture. Observations using a scanning electron microscope permitted visualization of dedifferentiated cells, and the reinitiation of meristematic activities resulted in the formation of a unipolar structure called a vegetative primordium. From these results, it is possible to conclude that regeneration efficiency (quality and quantity of material regenerated) in Jatropha curcas can be increased with the use of balanced medium constituents, growth regulators and modifications of culture conditions that include the absence of light.

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