EFECTO DEL FRACCIONAMIENTO DEL APICE CAULINAR PARA EL MEJORAMIENTO BIOTECNOLOGICO DE LA EMBRIOGENESIS SOMATICA EN PANICUM MAXIMUM CV. LIKONI

Abstract

An experiment employing whole, two-parted
and four-parted explants in an MS nutritive
medium, supplemented with 2,5 mg of 2,4 D/L
and 5 % of coconut-milk, was carried out in order
to study the caulinary apex fractionalization effect
upon the somatic embryogenesis of Panicum
maximum cv. Likoni in tissue culture "in vitro".
Contamination percentages, necrosis, dormant
explants, germinated apexes, embryogenic and
non-embryogenic calli and average calli diameter
were all measured in nine weekly evaluations
made starting on the third day of culture. Two-part
fractionalization lead to the somatic embryogenis
improvement of 7,5 % of the total explants
cultivated, as compared to the control, since the
number and strength of the calli was higher
during the eight weeks of evaluations in the
culture dynamics. Moreover, the somatic
embryogenesis started a week before the other
treatments applied reducing the necrosis
percentages and explants dormancy, while
increasing the average diameter of the calli in the
eight week of culture, which differed significantly
(P<0,05) from the treatment with four-part
fractionalization. It was confirmed that the
germination percentage was reduced with the
apex fractionalization, but the contamination
percentage was increased cause by the favoured
growth of the endophyte microflora.