BIODIVERSIDAD DE LA CUENCA MEDIA Y BAJA DEL RÍO CUNAS

La investigación se realizó en la cuenca media y baja del río Cunas, de abril de 2010 a marzo de 2011, con el objetivo de evaluar el estado actual de la biodiversidad de las comunidades vegetales y del ecosistema acuático, mediante indicadores de estructura y diversidad. El muestreo de la flora terrestre se realizó mediante los métodos de las líneas de Canfield y el de área. La evaluación de la diversidad vegetal, se realizó en base a la estructura y diversidad de las comunidades vegetales. La estructura, se determinó mediante el índice de valor de importancia y la diversidad, mediante los índices de riqueza de especies, de Simpson y de Shannon Wiener. Los resultados indican que las especies que presentan el mas alto índice de valor de importancia son Agave americana, Eucaliptus globulus y Baccharis sp, con valores de 99,63%, 58,06% y 49,7%, respectivamente, mientras que las especies que presentan el mas bajo índice de valor de importancia, son Cassia sp, Opuntia ficus indica y Alnus jurullensis con valores de 8,16%, 7,69% y ,73%, respectivamente. El índice de riqueza de especies (S = 10), indica que en la zona de estudio existen 10 especies vegetales. El índice de Simpson (λ = 0,25148), indica una probabilidad de 0,25148 de que si tomamos dos individuos al azar de una muestra, sean de la misma especie. El índice de Shannon Wiener (H ´= 0,3085), indica que el grado promedio de incertidumbre en predecir a que especie pertenecerá un individuo escogido al azar de una colección es de 0,3085. Las comunidades biológicas presentes en el ecosistema acuático, estuvieron conformadas por plancton, bentos, necton y vegetación acuática. Concluyéndose que la diversidad de la flora terrestre y de la flora y fauna acuática en la cuenca media y baja del río Cunas, presenta cierto grado de alteración, debido a las diferentes actividades antropogénicas desarrolladas en el área de influencia.

Expanded Potential Growing Region and Yield Increase for Agave americana with Future Climate

Rising crop risk for farmers and greater subsidy costs for governments are both associated with changing climatic conditions, including increased water scarcity. The resilience of Agave spp. in both hot and dry conditions, combined with their wide range of uses, position these plants as novel high-yielding crops suitable for both (i) a warming climate and (ii) agricultural regions with finite water resources. A simple model of the physiological response of Agave americana to variations in solar radiation, temperature, and precipitation was used to predict A. americana yields globally at a 4 km spatial resolution for both contemporary climate and high-end warming scenarios. The potential growing region for A. americana expanded by 3–5% (up to 3 million ha) and potential biomass production increased by 4–5% (up to 4 Gt of additional biomass) with climate warming scenarios. There were some declines in biomass with the climate warming projected in smaller dispersed locations of tropical South America, Africa, and Australia. The amount of water required for optimal A. americana yield is less than half of the current water required for other crops grown in semi-arid agricultural regions of the southwestern US, and a similar low water demand can be expected in other semi-arid regions of the world. Rock mulching can further reduce the need for irrigation and increase suitable cropland area for A. americana by 26–30%. We show that >10 Mg ha−1 y−1 of A. americana biomass could be produced on 27 million ha of cropland without requiring irrigation. Our results suggest that cultivation of A. americana can support resilient agriculture in a future with rising temperatures and water scarcity.

Hydroxypropyl methylcellulose nanocomposites containing nano fibrillated cellulose (NFC) from Agave americana L. for food packaging applications

Hydroxypropylmethylcellulose (HPMC) is popularly known as a hydrocolloid for potential use as a biopolymer film. The films of HPMC exhibit brittleness, lacking flexibility, but they can provide a gas barrier. With the aim of improving the HPMC film properties, nanofibrillated cellulose (NFC) from the succulent plant Agave americana L was incorporated as reinforcement material using the solution casting method. The films were prepared with three different amounts of NFC with glycerol as a plasticizer. The incorporation of the NFC into the nanocomposite films showed a 1,000-fold reduction in the gas permeability. However, significant improvements in the tensile strength (TS), the elongation at break (EAB), and Young’s modulus (YM) were only observed with 1% NFC. A higher moisture content (24.5%) and a higher solubility (59.5%) were observed in the HPMC/NFC-1 film, which also exhibited the best biodegradability loss of the films that were observed with a 92.8% degradation rate in 15 d of soil burial studies. Therefore, the results evidence that the HPMC/NFC films might be potentially suitable as food wrap packaging on perishable produce of fruits and vegetables to maintain their quality attributes and prolong the storage life.

BACTERIAL DIVERSITY WITH PLANT GROWTH-PROMOTING POTENTIAL ISOLATED FROM Agave americana RHIZOSPHERE

ABSTRACT Objective: Study the diversity of cultivable rhizospheric bacteria associated to Agave americana, and select native strains with potential as plant growth-promoting bacteria (PGPB). Design/methodology/approach: The isolated bacteria were phenotypically characterized. The genetic diversity and identity of the strains were revealed by genomic fingerprints and by sequencing of 16S rRNA gene. Plant growth promoting ability and plant inoculation assays were evaluated to know the potential as PGPB. Results: A total of 235 strains were isolated from A. americana rhizosphere and were classified within of 10 different bacterial genera. Rhizobium, Pseudomonas, Acinetobacter had high potential as PGPB. Study limitations/implications Cultivable approach was used to study rhizobacteria. A metagenomic study could expand the knowledge about the structure and diversity of bacterial community associated to A. americana. Findings/conclusions Rhizosphere bacteria have potential use as biofertilizer for the cultivation and propagation of A. americana and other agave species.

Morphological and genetic diversity of traditional varieties of agave in Hidalgo State, Mexico

The agaves are plants of cultural importance which have been used by humans for about 10,000 years and about 40 specific uses. The most culturally and economically important of those uses are for the production of fermented (pulque) and distilled beverages (mescal). Pulque continues to be produced in nearly all of Mexico, and the agaves used for this purpose have shown domestication syndrome. We carry out an ethnobotanical, morphological, and genetic analysis of the traditional varieties of pulque agave used in the production of aguamiel (agave sap) and pulque in the state of Hidalgo. We did semi-structured interviews, free listings, and tours with 11 agave managers. We analyzed morphology and studied genetic diversity and structure using nuclear microsatellites. We found wild-collected, tolerated, transplanted, and cultivated varieties of agave. This comprised 19 traditional varieties of pulque agave, 12 of them in production during the study, which corresponded to the species Agave americana, A. salmiana y A. mapisaga and five intraspecific entities. The varieties were grouped morphologically according to a management gradient; the wild-collected varieties were the smallest, with more lateral teeth and a larger terminal spine. The cultivated varieties clearly exhibited domestication syndrome, with larger plants and smaller dentition. The expected heterozygosity (He) of the varieties ranged from 0.204 to 0.721. Bayesian clustering suggested the existence of three genetic groups, both at the level of traditional varieties of pulque agaves and for management categories, a result that matches multivariate clustering. Pulque producers in the studied localities maintain high agrobiodiversity. The cultivated varieties exhibit domestication syndrome, as has been reported for other species of the genus with the same selection purposes. Our results support the hypothesis of a decrease in genetic diversity in crops compared to wild-growing agaves, which seems to be due to vegetative propagation, among other factors.