Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Estrategias para establecer pastos de temporal en zonas semiáridas de México

STRATEGIES TO FOR PRAIRIES ESTABLISHMENT PRAIRES UNDER RAINFED CONDITIONS FOR SEMIARID AREAS OF MEXICO

Auteur : Hernández Guzmán, Filogonio Jesús

Etablissement de soutenance : Colegio de Postgraduados (COLPOS) Consejo Nacional de Ciencia y Tecnología (CONACYT)

Grade : Doctorado en Ciencias, especialista en Ganadería 2013

Résumé partiel
In order to explore alternatives to increase prairies establishment probability under rain-fed conditions within semiarid areas, Sideoats grama, Blue grama, Buffel and Rhodes different seed propagules were physically and physiologically characterized and classified based on dimensions, using screens, in small, medium and large caryopsis ; also 100 embryos were dissected for each grass species and size. For greenhouse evaluation both native and introduced species were planted in pots using two caryopsis sizes : big and small, and plantlet development was sampled through destructive sampling at 20, 40, 60, 80, 100 and 120 days after planting (dap). For each date, weight for morphological component was measured (mg DM pl-1), growth rate (mg DM pl-1 d-1) for whole plants, specific leaf area (SLA ; cm2mg-1 pl-1), and leaf area duration (LAD cm2pl-1). Data was analyzed using a completely randomized design through SAS’ GLM. Caryopsides (CZ) and embryo size were essential for bigger plantlet development : leaves, stems, roots, inflorescence tissue, and leaf area during the studied period (P< 0.01) ; on the other hand, for introduced species, the effect was partial (P< 0.05). For SLA, native grasses did not show declination because of constant tiller production during the evaluated period (P< 0.01), while the SLA for exotic species decreases started 80 dap (P< 0.05). The LAD was always higher, for evaluated species, from 60dap (P< 0.01). Laboratory experiments were conducted in order to evaluate germination level and speed (SG) for the same species, using both diaspores (UD) as well as CZ, comparing different storage and peeling time whole diaspores were benefited manually and CZ obtained at the beginning of the experimental period (CB) and every two months (CT), viability was assessed every four months and based on this, for 16 months, caryopsis were planted on paper and diaspores into peat moss, based on pure live seed (LPS). Data was analyzed using a logistic model adjusted with LIFEREG of SAS. Higher germination and SG occurred at higher SZ and embryo in all evaluated species (P< 0.01). Native grasses’ vigor for CB remains best when these stay storage within the accessory bracts (AB) ; on the contrary, for exotic species which showed higher germination levels when AB are removed from the starting of the experimental period (P< 0.01).

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