REGENERATION CAPACITY OF DIFFERENT EXPLANTS FROM PROSOPIS-CHILENSIS SEEDLINGS

With the aim of study the failure of explants from adult Prosopis tree s to regenerate the whole plantlet, the basis for a biological test wa s devised checking the agamic reconstitutive capacity of different juv enile explants taken from 7 to 60 days-old seedlings of Prosopis chile nsis. Six types of explants were excised: embryonic axes, decapitated embryonic axes, shoot-rips, nodal sections, hypocotyl segments and roo t segments. These were cultured in vitro on MS media, viz. BM; BM + BA P 22 mu M + IBA 0.5 mu M; and BM + BAP 0.5 mu M + IBA 22 mu M, during 30 days. A high frecuency (85-95%) of plantlet regeneration has been o btained from embryonic and decapitated embryonic axes cultured on MS b asal medium without growth regulators. Less responses appeared from sh oot-tips and nodal sections. Neither hypocotyls nor root segments, in any medium assayed, regenerated the whole plantlet. The set down assay system might be suitable to detect growth inhibitory substances presu mably present in tissue extracts from adult Prosopis trees, which inte rfere in the regeneration process of their explants. The system compri ses a standard explant (embryonic or decapitated embryonic axes), a si mple nutrient medium (BM), no subculture, and controlled environmental conditions under which the standard explant may be accurately and rep roducibly grown and differenciated.