Slowly and non-digestible tissues in Elytrigia scabrifolia y E. Scabriglumis

The estimation of the percentages of slowly and non-digestible tissues allows the prediction 01the nutritive value of forages. In this study, the percentages of tissues in sheaths and blades of two species natives of the Salado Basin and abundant in the Pampas range pastures (Elytrigia scabrifolia y E. scabriglumis) were determined as a primary evaluation of their forage qualily. The estimations were done in the vegetative and reproductive stages. A split-plots design in space and time, with species as main plot, plant part (sheath or blade) as secondary plots, and three replications was used. Percentages of all leaf tissues were estimated by microscopic analysis of cross section and were grouped in rapidly and slowly plus non-digestible tissues. The variation of all leaf tissues between species, plant parts and growth stage, and the percentages variation of slowly and non-digestible tissues were analysed by principal components and by ANOVA, respectively. In all cases, the percentages of sclerenchyma were lower than 10% and those of slowly plus non-digestible tissues were lower than 45%. The percentages of slowly and non-digestible tissues did not differ (P<0.05) either between species (P<0.05) or plant parts, but increased 34% with the advancement of growth from the vegetativa to the reproductive stage. Although the percentage of slowly and nondigestible tissues suggest that both species have an acceptable nutritive value, this rating could be altered by the degree of forage lignification.Resúmenes de Trabajos presentados en otras publicaciones (por docentes de la UNLPam.) Publicado en Archivos latinoamericanos de producción animal, 5(Supl. 1): 118-121, 1997

Slowly and non-digestible tissues in Elytrigia scabrifolia y E. Scabriglumis

The estimation of the percentages of slowly and non-digestible tissues allows the prediction 01the nutritive value of forages. In this study, the percentages of tissues in sheaths and blades of two species natives of the Salado Basin and abundant in the Pampas range pastures (Elytrigia scabrifolia y E. scabriglumis) were determined as a primary evaluation of their forage qualily. The estimations were done in the vegetative and reproductive stages. A split-plots design in space and time, with species as main plot, plant part (sheath or blade) as secondary plots, and three replications was used. Percentages of all leaf tissues were estimated by microscopic analysis of cross section and were grouped in rapidly and slowly plus non-digestible tissues. The variation of all leaf tissues between species, plant parts and growth stage, and the percentages variation of slowly and non-digestible tissues were analysed by principal components and by ANOVA, respectively. In all cases, the percentages of sclerenchyma were lower than 10% and those of slowly plus non-digestible tissues were lower than 45%. The percentages of slowly and non-digestible tissues did not differ (P<0.05) either between species (P<0.05) or plant parts, but increased 34% with the advancement of growth from the vegetativa to the reproductive stage. Although the percentage of slowly and nondigestible tissues suggest that both species have an acceptable nutritive value, this rating could be altered by the degree of forage lignification.Resúmenes de Trabajos presentados en otras publicaciones (por docentes de la UNLPam.) Publicado en Archivos latinoamericanos de producción animal, 5(Supl. 1): 118-121, 1997

Bidens aurea (Asteraceae: Heliantheae): adventive cytotypes in Argentina

Volume: 75Start Page: 192End Page: 19

Analisis de la comunidad de malezas en trigo cultivado sobre distintos antecesores Analysis of weed community in wheat crop grown on different precedent crops

Comparou-se a composição e freqüência relativa das espécies e dos índices de diversidade e dominância da comunidade infestante de três áreas de trigo que foram cultivadas com trigo, milho e batata anteriormente. O estudo foi realizado na região de Mar del Plata, Província de Buenos Aires Argentina. Em cada área, realizou-se 40 amostragens de 1m2, dispostos de forma regular no campo, antes da aplicação dos herbicidas. Foram observadas pequenas diferenças entre as três comunidades florísticas levantadas, porém importantes mudanças foram verificadas na freqüência relativa de algumas espécies. Stellaria media foi a espécie mais freqüente, quando a cultura foi procedida de trigo e milho e sendo apenas superada por Solanum tuberosum quando a cultura do trigo teve como antecessor a cultura da batata. Algumas espécies como Chenopodium album, Zea maiz, Solanum tuberosum, Polygonum aviculares, Ammi viznaga, Veronica persica e Taraxacum officinalis incrementaram suas freqüências relativas nas áreas de trigo precedidas de milho e batata. Por outro lado, a freqüência relativa de outras espécies como Apium leptophyllum, Polygonum aviculares e Matricaria chamomilla decresceram nos mesmos locais. As mudanças específicas nas freqüências relativas não afetaram os parâmetros estruturais das comunidades infestantes, os quais mostraram valores similares de alta diversidade específica e baixa dominância.Relative frequency of species, diversity and dominance indexes of the weed community in three wheat crops grown in field of 40 ha where wheat, corn or potato were grown int he previous season, were analyzed. The study was performed in Mar del Plata, Province of Buenos Aires (Argentina). The ocurring species were registred in each of forth 1 m2 samples distributed in a regular arrangement at each field. This was done previous to application of herbicides. Small differences between communities in floristic composition and richness were observed. But, important changes in the relative frequency of some species were observed. Stellaria media was the most frequent specie in wheat -wheat and corn-wheat sequences, and was only exceeded by Solanum tuberosum in potato-wheat sequence. The relative frequency of some species such as Chenopodium album, Zea maíz, Solanum tuberosum, Polygonum aviculare, Ammi viznaga, Veronica persica and Taraxacum officinallis was increased in wheat crop cultivated on corn or potato. On the other hand, the relative frequences of other species such as Apium leptophyllum, Polygonum convolvulus and Matricaria chamomilla decreased in the same sites, The specific changes in the relative frequences did not affect the structural indexes of weed communities, which showed a similar and high diversity index and low dominance

NR 08. Slowly and non-digestible tissues in Elytrigia scabrifolia y E. scabriglumis

The estimation of the percentages of slowly and non-digestible tissues allows the prediction of the nutritive value of forages. In this study, the percentages of tissues in sheaths and blades of two species natives of the Salado Basin and abundant in the Pampas range pastures (Elytrigia scabrifolia y E.scabriglumis) were determined as a primary evaluation of their forage quality. The estimations were done in the vegetative and reproductive stages. A split-plots design in space and time, with species as main plot, plant part (sheath or blade) as secondary plots, and three replications was used. Percentages of all leaf tissues were estimated by microscopic analysis of cross seccion and were grouped in rapidly and slowly plus non-digestible tissues. The variation of all leaf tissues between species, plant parts and growth stage, and the percentages variation of slowly and nondigestible tissues were analized by principal components and by ANOVA, respectively. In all cases, the percentages of sclerenchyma were lower than 10 % and those of slowly plus non-digestible tissues were lower than 45 %. The percentages of slowly and non-digestible tissues did not differ (P < .05) either between species (P < .05) or plant parts, but increased 34 % with the advancement of growth from the vegetative to the reproductive stage. Although the percentage of slowly and non-digestible tissues suggest that both species have an acceptable nutritivo value, this rating could be altered by the degree of forage lignification