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Universidad Nacional del Sur

Efecto de la humedad edafica sobre aspectos morfológicos y funcionales de tres leguminosas patagónicas relativos a su uso y conservación

Stronati, Mónica Susana

Titre : Efecto de la humedad edafica sobre aspectos morfológicos y funcionales de tres leguminosas patagónicas relativos a su uso y conservación

Auteur : Stronati, Mónica Susana

Université de soutenance : Universidad Nacional del Sur

Grade : Doctor en Biologica

Résumé
Biodiversity conservation and desertification control in Patagonia must necessarily be related to the identification of plant species that could be used for this purpose. The general objective of this work was to evaluate different levels of water disponibility effects on germination, establishment and survival of the studied species and their eventual potentiality for N fixation. It was also studied the possible existence of xeromorphic characters and/or tissue specializations that could allow them to persist and fix N at different conditions of water stress. Natural populations of Astragalus cruckshanksii (Hook. et Arn.) Griseb., Glycyrrniza astragalina Gillies ex Hooker et Arnott and Adesmia lotoides Hook.f., can be found at different locations of the Phytogeographic Province of Patagonia, where seeds and rhizospheric soil of the three species were colected at different times, as well as portions of A. lotoides individuals, in order to develop this study. Germination and emergency were determined. Trials for moisture gradient response was conducted for all the plant species. For all the treatments stem long, leaves and leaflets numbers, leaf surface, ramifications, nodes number, main and laterals root long. were registered. There were taken tissue samples for further analysis and dry matter from shoot and root, nodulation was registered, as well as N biological fixation and N total content. G. astragalina and A. lotoides are rhizomatic plants that during the first stage of their development have a stem base or crown that could be similar to the one described for A. cruckshanksii. All species shown underground areas with buds for persistence and growing. At lower levels of soil moisture, less mass of meristematic tissue was formed. This conducted to a lower development of buds bank and least differentiation of secondary tissue which in turn generated smaller cells and thinner leaflets. Germination was hampered in A. cruckshanksii and A lotoides from -0,8 MPa, and G. astragalina decreased its germination potential from -0,4 MPa. A.cruckshanksii was the species that shown the best emergency behavior. Plants are affected by water disponibility at the analyzed parameters, but it is possible that they could present genetic adaptatives characters to water deficit. The study also demonstrated survival, infectivity and efectivity of native Rhizobium strains, and, on the other hand, nodulation capacity of Legumes analyzed at the water deficit conditions of the treatments. A. lotoides got the highest total N percentage in the underground biomass at the 15% soil moisture treatment.

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Page publiée le 10 mars 2020