Acacia angustissima (prairie acacia).

A. angustissima is a thornless shrub up to 4 m in height. This species is originally from Central America and tolerates a wide range of soils and climates, from high altitude pine-oak forests to extremely dry habitats in the lowlands of Mexico. A. angustissima is a deep-rooted nitrogen fixing pioneer, and is valuable in reducing soil erosion. It is a useful browse species, and may also be planted on acid soils. The species flowers prolifically and is a valuable honeybee plant. A. angustissima has shown great promise in recent alley cropping experiments in lowland Papua New Guinea (Brook, 1992), and may outperform more familiar species of Calliandra and Leucaena in biomass production. It performed best in a multipurpose tree evaluation in a range of sites in the same region from 20-1650 m in altitude (Brook et al., 1992). This species also showed promise in a range of trial sites in Zimbabwe, Ghana to Hawaii. Trials so far have been based on seed collected on an opportunistic basis, and further research is required on genetic improvement of the species throughout its range for international provenance trials. In some regions it may become an aggressive colonizer.

Integrated Soil Fertility Management Options for Maize Production and Sustainability in the Western Highlands of Cameroon

Background: Continuous cultivation without fertilizer application and soil erosion are responsible for plant nutrient depletion and yield decline of major food crops in Sub-Saharan Africa.Methods: Nutrient status of Calliandra calothyrsus, Leucaena leucocephala, Acacia angustissima and Cassia spectabilis were characterized. Field experiments were conducted over two years in the Western Highlands of Cameroon to evaluate the effects of the application of leaf biomass of agroforestry tree species and mineral fertilizers on maize yield performance. The residual effects on soil physicochemical properties were also investigated for umbric Cambisols of Babungo and ustic Oxisols of Bansoa. Ten treatments encompassing; sole leaf biomass of Calliandra calothyrsus, Leucaena leucocephala, Acacia angustissima and Cassia spectabilis, leaf biomasses combined with NPK fertilizer, sole NPK fertilizer and absolute control were laid in a randomized complete block design and replicated three times. Data were subjected to analysis of variance and the Duncan Test (p < 0.05) used for mean separation.Results: All the species characterized had nitrogen, polyphenol and lignin contents greater than 2.5 %, 5 % and 15 % respectively. Significant differences (p < 0.05) were observed among treatments on maize growth, productivity parameters and soil chemical properties for both soil types. The highest maize grain yields were recorded in plots amended with 1 t/ha of biomass of Calliandra calothyrsus or Leucaena leucocephala as well as1.5 t/ha of biomass of Acacia angustissima and Cassia spectabilis plus mineral fertilizer (50 N+ 37.5 P2O5 + 45 K2O) on both soils compared to other treatments.on umbric Cambisols and ustic Oxisols respectively. The residual effects of treatments on soil chemical properties showed severe nutrient depletion in control plots and those amended with sole inorganic fertilizer.Conclusions: Combined application of agroforestry tree biomass and inorganic fertilizers remains an appropriate technology to enhance maize yield and sustain production of resource-limited farmers of acid tropical soils..

Chemical Composition and Digestibility of Six Species of Fodder (Fabaceae)

Objectives: To determine the chemical composition and in vitro digestibility of Acacia angustissima, Dalea spp., Desmodium spp., Leucaena leucocephala, Phaseolus vulgaris and Tephrosia vicioides (Fabaceae) fodder species. Design/Methodology/Approach: Crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), crude lignin (CL), cellulose (Cel), hemicellulose (Hcel), cellular content (CC) and in vitro dry matter digestibility (IVDMD) were determined. The design was completely random with three repetitions. The variables were correlated by pairs and the means of the species were compared with Tukey’s test (P<0.05). Results: Dalea spp. had the highest crude protein (17.7%), followed by A. angustissima (15.9%) and L. leucocephala (14.1%). A. angustissima (73.2%), Dalea spp. (74.9%) and P. vulgaris (77.5%) showed the highest IVDMD. L. leucocephala, Tephrosia vicioides and Desmodium spp. showed the lowest values of CP (14.1, 11.8 and 12.3%, respectively) and IVDMD (70.4, 70.2 and 64.9%, respectively). Desmodium spp. showed high levels of NDF (59.2%), ADF (41.4%), CL (17.5%), Cel (29.7%) and Hcel (17.8%) (P?0.05). IVDMD showed positive correlation with CC and negative correlations with NDF, CL, and Hcel (P<0.05). Study Limitations/Implications: Desmodium spp. showed high content of CL and low values of CP and IVDMD, therefore supplements should be added when used in animal feed. Findings/Conclusions: Dalea spp. showed low levels of lignin and high levels of protein and digestibility, making it posible to use as feed for ruminants

ENSAYO DE LEGUMINOSAS PARA LA REFORESTACIÓN DE LA 2a SECCIÓN DEL BOSQUE DE CHAPULTEPEC

La Segunda Sección del Bosque de Chapultepec es un sitio de preservación ecológica, generación de servicios ambientales y de beneficios recreativos, principalmente, para los habitantes de la Ciudad de México. En los últimos años se ha registrado una declinación y disminución de su cubierta forestal, por lo que es necesario llevar a cabo programas de reforestación que se realicen con las especies apropiadas al sitio. Se realizó un ensayo de seis leguminosas arbóreas con el objetivo de evaluar su supervivencia y tasas de crecimiento en altura y diámetro basal; en el primer rubro, el valor final fue de 100 a 92.59%, en función de la especie, aunque no hubo diferencias significativas entre ellas. La tasa de crecimiento en altura fue mayor y significativamente diferente en Albizzia occidentalis y Senna multiglandulosa, respecto a los otros taxa; mientras que la correspondiente al diámetro resultó superior en S. multiglandulosa, Acacia angustissima y A. occidentalis. En contraste, Leucaena esculenta presentó las cifras más bajas en ambas variables, pero no difirió significativamente de Eysenhardtia polystachya, ni de Lysiloma divaricata. En algunas plantas se registraron daños por vandalismo, así como por el ataque de plagas. A pesar de ello, los resultados permiten afirmar que estas son una buena opción para la reforestación del área de estudio, lo que confirma la importancia de realizar ensayos de especies previos a los programas de reforestación urbana.

Relationships between Structures of Condensed Tannins from Texas Legumes and Methane Production During In Vitro Rumen Digestion

Previous studies showed that a series of purified condensed tannins (CTs) from warm-season perennial legumes exhibited high variability in their modulation of methane production during in vitro rumen digestion. The molecular weight differences between these CTs did not provide correlation with either the in vitro CH4 production or the ability to precipitate bovine serum albumin. In an effort to delineate other structure-activity relationships from these methane abatement experiments, the structures of purified CTs from these legumes were assessed with a combination of methanolysis, quantitative thiolysis, 1H-13C HSQC NMR spectroscopy and ultrahigh-resolution MALDI-TOF MS. The composition of these CTs is very diverse: procyanidin/prodelphinidin (PC/PD) ratios ranged from 98/2 to 2/98; cis/trans ratios ranged from 98/2 to 34/66; mean degrees of polymerization ranged from 6 to 39; and % galloylation ranged from 0 to 75%. No strong correlation was observed between methane production and the protein precipitation capabilities of the CT towards three different proteins (BSA, lysozyme, and alfalfa leaf protein) at ruminal pH. However, a strong non-linear correlation was observed for the inhibition of methane production versus the antioxidant activity in plant sample containing typical PC- and PD-type CTs. The modulation of methane production could not be correlated to the CT structure (PC/PD or cis/trans ratios and extent of galloylation). The most active plant in methane abatement was Acacia angustissima, which contained CT, presenting an unusual challenge as it was resistant to standard thiolytic degradation conditions and exhibited an atypical set of cross-peak signals in the 2D NMR. The MALDI analysis supported a 5-deoxy flavan-3-ol-based structure for the CT from this plant.