Germination and development of native species under the effect of allelopathic exudates of a superdominant species

In plant dynamics, some species have an aggressive colonizing pattern (they may even become superdominant). This is the case of Sesbania virgata (Cav.) Pers., a shrub-tree species that, for a long time, was used in restoration programs due to its fast growth, short reproductive cycle, and little selectivity to unfavorable soil conditions. Thus, this study was carried out to analyze its allelopathic effect upon the seed bank of two native species with which it co-occurs in the environment. For this, seeds were collected from two S. virgata populations, one that produced and another unable to produce the allelochemical catechin (which is very abundant in this species). They were sown in 25-L pots with three substrate types under two development environments. After 16 months (during which the germination and development of the species were monitored), Mimosa bimucronata and Peltophorum dubium seeds were planted beneath S. virgata canopy and evaluated. S. virgata fully germinated in all environmental conditions but its height (above 100 cm versus 60 cm, on average) and diameter (above 18 mm versus 6 mm, on average) developed better under full sun than in the shade. M. bimucronata showed reduced n total germination values and speed when sown under S. virgata seedlings, with values from 40 to 50% of those found without the presence of the latter species. P. dubium was tolerant of S. virgata. This pattern was also verified for early development. S. virgata may be used in restoration plantations, although it is necessary to consider its rapid development and allelopathic potential on some native species.