Agriculture is a co-evolutionary process between society and nature. Agroecology is an environmental science which focuses on ecosystem-culture and society-nature interactive systems, the effect of human intervention in the transformation of ecosystems. The central objects are agroecosystems and the units of study are production units. These production units are conceived of as agricultural systems and are found in the crossroads of multiple interactions between biophysical, socioeconomical, cultural, and production components, which must be analyzed with an integrated concept. In the present study, a characterization and typification of the citrus agroecosystems of the department of Meta were pursued (Colombia). The pertinence of implementing the methodology designed by the Latin-American Center for Rural Development (Centro Latinoamericano para el Desarrollo Rural-RIMISP) was evaluated, grouping the variables with a focus on an analysis of livelihoods. A survey and interview were defined as methods of collecting the primary information in the municipalities of Puerto López, Villavicencio, Granada, Lejanías, Guamal and San Martin, where 78.4% of the citrus area of the department is found. This study involved the selection and definition of the evaluation variables, validation and adjustment of said variables, collection of primary and secondary information, and the application of multivariate statistical analysis techniques to conform and characterize the recommendation domains or groups. The more important results indicated that it is possible to increase knowledge of the interrelations that exist between the different components of farm agroecosystems and their relationship with the principal agroecological structure. The existence of six agricultural groups or recommendation domains was established, with some productive characteristics very similar within the group but very heterogeneous to the outside of the group, with particular necessities.
This study was conducted to determine the richness and composition of weed communities associated with banana plantations in Magdalena department, Colombia. Between September 2016 and May 2017, a total of 164 hectares were assessed over four agroecological zones (Alta, Media, Baja and Norte); in each zone, three representative farms were selected where, through zigzag paths, botanical collections were made in cultivated lots. Information on life cycle, growth habit and origin of each species was included. The floristic composition was represented by 204 species distributed among 143 genera and 54 families. Poaceae, with 31 species, was the family with the highest species richness, followed by Fabaceae (12) and Asteraceae (11). From the total species recorded, 113 are perennial (55%) and 91 are annual (45%); 141 species are herbaceous (68%), 38 are climbers (20%), and 25 are arboreal or shrubby (12%). Native species predominate over introduced species. The species richness does not differ significantly between the sampling zones, but the weed community composition does. The presence of common species reported as important weeds worldwide was recorded in the four zones. However, some species were recorded in only one of the zones, generating a differential composition pattern. Comparison with local inventories showed changes in the composition of the weed complex over time. The presence of various species not previously considered weeds in the banana crops of this region is highlighted.
Calotropis procera (Aiton) Dryand (Apocynaceae) is a native species in tropical and subtropical Africa and Asia. However, due to its fast growing and drought-tolerant, it has become an invasive species when it was introduced into Central and South America, as well as the Caribbean Islands. Currently, C. procera displays a wide distribution in the world. Invasiveness is important, in particular, because many invasive species exert a high reproductive pressure on the invaded communities or are highly productive in their new distributed areas. It has been suggested that a very deep root system and a high capacity to reduce stomatal conductance during water shortage could allow this species to maintain the water status required for a normal function. However, the true mechanism behind the successful distribution of C. procera across wet and dry environments is still unknown. C. procera leaves were collected from 12 natural populations in Brazil, Colombia and Mexico, ranging from wet to dry environments during 2014-2015. Many traits of morphology and anatomy from these distinct morphotypes were evaluated. We found that C. procera leaves had a considerable capacity to adjust their morphological, anatomical and physiological traits to different environments. The magnitude of acclimation responses, i.e., plasticity, had been hypothesized to reflect the specialized adaptation of plant species to a particular environment. However, allometric models for leaf area (LA) estimation cannot be grouped as a single model. Leaves are narrower and thicker with low amounts of air spaces inside the leaf parenchyma in wet environments, while they are broader and thinner with a small number of palisade cell layers in dry environments. Based on these, we argue that broader and thinner leaves of C. procera dissipate incident energy at the expense of a higher rate of transpiration to survive in environments in which water is the most limiting factor and to compete in favorable wet environments.
Leaf area measurement is pivotal for plant physiologists. Hence, accurate measurement of their leaf area is incredibly relevant in agronomic terms. The plant Stevia rebaudiana is a sucrose-free plant species that is now vital to the global production of sucrose-free foods. Here, we estimated S. rebaudiana leaf area using a nondestructive methodology comprising allometric equations. Through leaf length (L), leaf width (W), and/or their product (LW) the leaf area was determined. One thousand leaves were sampled from four distinct S. rebaudiana genotypes for model construction. Linear or power models were generated, and the best equation was selected using a statistical criterion. The statistical criteria indicated that the linear models best suited all genotypes tested, included a function of LW, exhibited increased stability, and precisely estimated coefficients. ANOVA revealed that both generalized and combined equations were feasible. Nevertheless, grouping all genotypes into a single model was not possible as the genotype leaf architectures were very dissimilar.
Comparative analysis of salt-induced changes in the leaves proteome of two contrasting Jatropha curcas genotypesAnálise comparativa no proteoma, induzido por salinidade, em folhas de dois genótipos contrastantes de Jatropha curcas
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