RESUMEN
The ecosystems of the Mediterranean regions are severely threatened by human activity, and although we have made progress in physical restoration measures, little is known about the interactions between the plants of these biomes. The objective of this study is to contribute to document interactions between seeds and seedlings of three woody species native to Chile (P. chilensis, Q. saponaria and A. caven), which could be used for restoration actions (e.g., after forest fires). In a first experiment, we evaluated the germination response, the initial elongation and the interactions between the seedlings that germinate exposed to the chemical compounds of the other species. In a second experiment, we compared the survival and growth of seedlings in monospecific versus bispecific mixtures, using a substrate similar to that which is present after a wildfire. Seed extracts of teguments promoted germination of P. chilensis, but cotyledons and whole seed extracts inhibited germination of only one species, Q. saponaria, with very high intensity. The effects of the extracts on initial seedling elongation were more variable, including five inhibitions and one facilitation. Negative effects on germination and elongation included two cases of autotoxicity. The survival of seedlings grown in mixtures showed only two differences between monospecific and bispecific mixtures, both positive, constituting a reciprocal effect between two species. Only in one case was there a significant difference in seedling growth, which was root growth inhibition. Indeed, these results reveal an interaction between species, the type and intensity of which varies according to the condition of the seed or seedling. The negative effect found in seedling root growth reflects an allelopathic interaction that conditions a vital aspect for the establishment of these species, so this information is an opportunity to improve the establishment conditions in future reforestation projects, by avoiding particular species or promoting their proportion in plantation mixtures, either by planting or direct seeding.
Asunto(s)
Plantones , Árboles , Ecosistema , Bosques , Germinación/fisiología , Humanos , Bases del Conocimiento , Extractos Vegetales , SemillasRESUMEN
Data on the germination rates of four tree species, natively founded in the Chilean Mediterranean-climate zone, were determined by germination in crop chambers. The obtained data were used to interpolate or extrapolate the time taken for 50% of seeds to germinate in each case. These results are useful for regional native forest research and, in a broad sense, for its use in models to study germination dynamics in Mediterranean-climate zones.
Asunto(s)
Caesalpinia , Prosopis , Chile , Bosques , Germinación , Quillaja , Semillas , ÁrbolesRESUMEN
Lymphoproliferation inhibition and cytotoxicity of a number of lipidic aminoacids, aminoalcohols and diamines were evaluated as a preliminary screening to select potential immunomodulators. The four most potent/less toxic compounds were submitted to delayed hypersensibility (DTH) assays to define the best to be evaluated further Graft-vs-Host, NO production and other immunoevaluation (CD4(+), CD45, CD8, CD11b, I-Ek, and NK cells) assays, to establish their immunomodulation potential for being further considered as auxiliary agents for vaccination against some parasitic infections. Compounds 5d, 6d, 6f, 7a, and 9a, fairly inhibited the lymphoproliferation (71.6-79.5%, at 3.2-2.4 nM), while the aminoalcohol derivative 6f and the diamine 7a gave the most promising results in the DTH assays. Diamine derivative 8b induced nitrite production on normal macrophages, whereas compounds 6f and 7a induced nitrite production on LPS pre-stimulated macrophages. These two last compounds have been selected to follow in vivo vaccination assays.