PHENOLIC OXYDATION, TYPE OF EXPLANT AND NUTRITIVE MEDIA IN Peltophorum dubium (SPRENG.) TAUB.’S IN VITRO ESTABLISHMENT

Abstract

Peltophorum dubium (Spreng.) Taub. is a heliopylous, a native forest species with wide geografic dispersion, occuping a pioneer role in open areas, hencoops and degradated woods. Showing a fast growth, it adapts easily and it is highly recommended for homogeneous reforest. The timber is used in industrial furniture, civilian, naval and military constructions. The micropropagation is a technique used succesfully, allowing a fast increase of the number of plants genetically identical considering the superior types. The  work’s objectives are: to evaluate the effect of the light on phenolic oxydation and to determinate the most appropriate nutritive medium and type of explant for in vitro establishment of Peltophorum dubium. Two experiments were accomplished. In the first one, apical segments were cultivated in MS base medium at 25±3°C, during seven days in the dark; after that, they  remained in the presence of light (photoperiod of 16h) for 14 days. In the other treatment, the explants stayed under light during the whole experiment (21 days). Completely random design with five replicates and four experimental units (EU) were used. Phenolic oxydation did not occur in any of the analyzed treatments. In the second assay, apical segments and nodal segments were cultivated in MS base medium and WPM medium. The explants stayed in the growth room during 16h of photoperiod and luminous intensity of 20 μmol.m².s^-1, supplied with cool white fluorescent lamps, at 25±3°C. The EU was composed by one 150mL flask with 30mL of nutritive medium and one explant. Completely random design with factorial outline 2 x 2 (nutritive medium and type of explant) and five replicates by treatment, each replicate with four EU, were used. After 49 days, the following elements were evaluated: survival, establishment, root presence, calli presence, numbers of nodes, number of leaves and shoot height (mm). The data of survival, establishment, root presence and calli presence were analyzed for qui-quadrado test. The other variables were submitted to variance analysis. In this experiment, MS base medium is more efficient than WPM medium in the in vitro establishment of Peltophorum dubium. There are no statistical differences among apical segment and nodal segment.

bic�.<��t coefficients of additive genetic variation presented greater values in the TP-71 test from Wetar and TP-68 from Alor, and presented similar values in other tests for the diameter at breast height (DAP) characteristic. Selection gains were estimated at values of 12.8; 22.9; 9.5; 21.0 and 25.3%, and the effective population size (N_e) at values of 60.2; 58.0; 131.8; 167.9 and 224.1 for the TP-67, TP-68, TP-69, TP-70 and TP-71 tests, respectively. A selection gain of 26.8 % was obtained in the clonal seed orchard with selection of 21 plants that were carriers of the greatest additive genetic values. In both procedures, the values of the genetic parameters were similar, except among families, in which the  REML procedure em obtained higher values with accuracy higher than 70% in all populations, proving to be appropriate for this purpose.