Germination and development of 'Precocinho' peach embryos: asepsis and use of PPM tm in culture medium.

ABSTRACT.Embryo culture is a technique used to rescue immature embryos which would not germinate under natural conditions. However, one of the biggest problems of this process is the contamination by microorganisms. The objective of this work was to test asepsis methods and the use of PPMTM (Plant Preservative MixtureTM) in the culture medium for the germination and development of 'Precocinho' peach embryos. After extraction from the fruits, seeds were submitted to treatments with thimerosal, sodium hypochlorite (NaClO), flame sterilization and moxifloxacin hydrochloride, in culture medium with and without addition of PPMTM, totaling nine treatments. The experimental design was completely randomized, with 20 replicates per treatment. Three evaluations were performed: in vitro establishment (at 55 days of cultivation), embryo development (at 65 days of cultivation) and acclimatization (20 days after transplanting in the greenhouse). Six treatments did not had any contamination, on the first evaluation. However, 65 days after culture, the NaClO with PPMTM addition presented the best results for the variables analyzed. The average seedling survival was 81.6%, after acclimatization. The use of sodium hypochlorite with the addition of PPMTM is shown as the most efficient treatment, among the tested ones, for the germination and development of 'Precocinho' peach embryos