Breeding strategies in Melilotus albus Desr., a salt-tolerant forage legume

Melilotus albus Desr. is recognized as one of the species with greatest potential as a forage source for ruminants in saline rangelands. The objectives of the current research were threefold: (1) to estimate heritability and genetic correlation of traits associated with winter forage production and regrowth capacity in M. albus prebreeding material, as measured in spaced plants grown in a nonsaline environment; (2) to evaluate winter forage production of a selected population grown in plots at sites with contrasting soil salinities; and (3) to evaluate the agronomic performance of blended (mixed) populations and monocultures of M. albus grown in plots. Results indicated presence of genetic variability associated with winter production and regrowth capacity in a prebreeding population selected for one trait, viz. late flowering. Results also showed that selection in a nonsaline environment did not modify the relative salinity tolerance of M. albus populations. Finally, varietal mixtures (blends) of two selected populations showed a slight increase in and more seasonally balanced dry matter (DM) yield than monocultures. Mixtures combined favorable characteristics from the two selected populations (i.e., highest winter forage production, as expressed in the SP1 population, and highest regrowth capacity, as expressed in the SP2 population). Furthermore, results indicated that M. albus genotypes naturalized in Argentina could be used as genetic resources for sweet clover breeding for saline environments and that alternative breeding approaches could improve forage productivity in saline environments.Fil: Zabala, Juan Marcelo. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Marinoni, Lorena del Rosario. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Giavedoni, Julio Alberto. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Schrauf, Gustavo Enrique. Universidad de Buenos Aires. Facultad de Agronomía; Argentin

Analisys of distribution and stomatal density in Trichloris (Chloridoideae, Poaceae), under different water regimes

Trichloris crinita y T. pluriflora son gramíneas perennes nativas de Argentina que presentan potencialidad productiva como forrajeras para regiones áridas y semiáridas. Los objetivos del presente trabajo fueron analizar para ambas especies las variaciones en la distribución y densidad estomática foliar ante dos regímenes hídricos diferentes y su asociación con las precipitaciones en el lugar de origen. Se caracterizaron seis introducciones para cada especie, implantando dos ensayos, uno en ambiente húmedo y otro en ambiente seco, realizándose mediciones de dimensiones foliares y recuentos estomáticos en cada material para cada ambiente. El Análisis de Componentes Principales representó el 73,3% de la variación sobre los dos primeros ejes, respondiendo al efecto del ambiente de evaluación sobre los parámetros estomáticos y a las diferencias entre especies para las dimensiones foliares. Para T. crinita se observaron diferencias significativas entre introducciones para la mayoría de las variables analizadas en ambos ambientes. Para T. pluriflora, las variaciones entre introducciones fueron evidentes solamente en ambiente húmedo. Las variaciones observadas presentaron correlación con las precipitaciones en el sitio de colecta únicamente para T. crinita. Las variables aquí empleadas resultaron de utilidad para la caracterización de los materiales analizados; se discute su implicancia para la conservación del recurso fitogenético.Analisys of distribution and stomatal density in Trichloris (Chloridoideae, Poaceae), under different water regimes. Trichloris crinita and T. pluriflora are perennial grasses native from Argentina that have productive potential as forage for arid and semi-arid regions. The objectives of the present work were to analyze in both species the variations in leaf stomatal distribution and density under two different water regimes and their association with rainfall at the place of origin. Six introductions for each species were characterized. Two trials were implemented, one in a humid environment and the other in a dry environment. Measurements of foliar dimensions and stomatal counts in each material for each environment were made. The Principal Component Analysis represented 73.3% of the variation on the first two axes, responding to the effect of the evaluation environment on stomatal parameters and to the differences between species for their foliar dimensions. Significant differences were observed between introductions of T. crinita in both environments for most of the variables analyzed. Variations between introductions of T. pluriflora were observed only in humid environment. The observed variations correlated with rainfall at the collection site only for T. crinita. The variables used here were useful for the characterization of the materials analyzed; their implications for the conservation of this plant genetic resource are discussed.Fil: Trod, María Amalia. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Tomas, Pablo Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral; ArgentinaFil: Cervigni, Gerardo Domingo Lucio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Zabala, Juan Marcelo. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Marinoni, Lorena del Rosario. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Giavedoni, Julio Alberto. Universidad Nacional del Litoral; Argentin