Resumen

YEPEZ, Florángel  y  ARBOLEDA, María Elena. Pre-germinative treatments to promote emergency in pink orchid tree (Bauhinia monandra Kurz) and yellow oleander (Thevetia peruviana (Pers) Schum), species for the urban arboriculture. Bioagro [online]. 2009, vol.21, n.1, pp.15-22. ISSN 1316-3361.

The selection of the suitable species is fundamental for the forestry of cities; however, the supply of appropriate ornamental trees suitable for tropical conditions is scarce; so it is important to develop the most convenient production techniques. The objective of this investigation was to evaluate the effects of different pre-germinative treatments on the plantlet emergency, following the germination of pink orchid tree (Bauhinia monandra Kurz) and yellow oleander (Thevetia peruviana (Pers) Schum). In pink orchid tree, treatments of soaking the seeds in hot water and sulphuric acid for different times were evaluated, along with mechanical scarification in electric blender for two different times, and a control of intact seeds. In yellow oleander, the treatments were partial or total mechanical removal of epicarp, along with a control consisting in the intact fruits. Two experiments (one for each species) were established in completely randomized design with four replications and 75 seeds per plot. Emergency curves were developed, and the beginning time of the process (TI), number of days to 50 % of total emergency (TE₅₀) and the lapse between the occurrence of 10 and 90 % of emergency (TE_10-90) were determined. In pink orchid tree the chemical scarification with sulphuric acid by 5 minutes of soaking favored the emergence (95.6 %) and the speed of the process (1 day for TE_10-90), whereas the treatments with hot water did not allow any emergency. In seeds of yellow oleander, the complete removal of pericarp allowed a maximum of 61.6 % emergence, while very low values were found when using intact fruits.

Palabras clave : Latency; ornamental trees; scarification; sexual propagation; urban forestry.