Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Background. The live weight (LW) and morphometric variables of sheep are useful characteristics to generate adequate criteria for genetic improvement and conservation of Creole animal resources. Objective. To establish morphological relationships and through them predict LW of females and males in Creole sheep of the Oaxacan Mixteca, Mexico. Methodology. LW, thoracic perimeter (TP), height at withers (HW), back length (BL), cane perimeter (CP), head length (HL), neck length (NL), abdominal perimeter (AP) and rump width (RW) were recorded in 720 Creole sheep in 24 production units, measured in animals of both sexes. First, they were analyzed using general linear model procedures to determine the effect of sex on the variables of interest, and then, they were analyzed using discriminant analysis. Simple correlations between morphometric variables were calculated and step-by-step multiple linear regression equations were generated to predict LW. Results. Differences were found between sexes for LW and morphometric measures, which were correlated (p ≤ 0.05). The variables TP, AP and BL had the highest correlations (0.92, 0.90 and 0.89, respectively) and the variables CP, NL and RW, the lowest (0.75, 0.82 and 0.83, respectively). The statistical models explained a large proportion of the total variability (R2 from 85 to 91 %). According to sex, males had R2 (0.90 to 0.94) higher than females (0.83 to 0.89). In both cases TP and HW were the most important characteristics for predicting LW. Conclusions. Under the conditions of this work, the model that included TP and HW was the one that best predicted the LW of the Creole sheep of the Oaxacan Mixteca. It is recommended to use different equations for each sex and training of sheep producers in the use of those equations.

Background. Rural associative organizations (RAOs) have been considered as key actors for rural and agricultural development. In fact, the RAOs are characterized by their flexibility, since they can perform various functions in rural territories that can be economic, productive, political, social and environmental. Objective. This study used a literature review in order to determine the multifunctionality of RAOs based on the typification of organizational models, through a qualitative process of grouping categories and variables, in order to enrich theoretical conceptualization and future research analysis. Methodology. A systematic study of the literature was carried out in the global databases: ScienceDirect, Elsevier, EBSCO, SCOPUS, Springer, Wiley and Google Scholar, Scielo and REDALYC, using as key search terms in both Spanish and English: rural associativity, associativity rural cooperative, rural associative enterprises, dimensions of associativity, agrarian associations, associative forms and family farming, associativity and public policies, producer organizations, associativity and chains. Results. The study made it possible to determine four multifunctional models of RAOs: (i) Associative model as an intermediary in innovation; (ii) Rural agribusiness associative model; (iii) Associative model promoting leadership and empowerment; (iv) Associative model for local agri-food supply. Implications. The RAOs models proposed in this study are framed within key strategic functions that can be used to promote associativity in relation to the specific needs of the territories. This has implications for public policy at the local and micro-regional level. Conclusions. Despite the existence of extensive contributions on rural associativity generating various study frameworks, the state of the art and systematic and critical analysis allowed the grouping of four multifunctional models of RAOs. Each associative model pursues different purposes that, of course, can be transversal, but which are limited to specific strategic functions to promote different initiatives in the context of local rural development, as well as for the design of public policies with a territorial approach, within the framework of the availability of association capabilities and public-private institutions.

Food insuf ficiency in corn and water and fertilizer crisis worldwide demand ef ficiency in the use of resources, increasing or conserving production. Thus, the objective of this research is to explore the response of four white maize hybrids released for valles Altos in two environments considering two population densities, two doses of fertilization and an unfertilized control group. Hybrids were evaluated in a factorial arrangement in Cuautitlan (FESC-UNAM) and Texcoco (CEVAMEX), Mexico State, at two planting densities (D1 = 75,000; D2 = 90,000 plants ha-1) with three fertilization treatments (F1 = 160-80-00, F2 = 120-40-00, F3 = 00-00-00). The completely randomized block design experiment was made up of the treatments and the combination of the factors 2×4×2×3 established in three repetitions. The means were compared with Tukey’s test (P < 0.05). In FESC-UNAM with less total water, the result of grain yield and water productivity was 5.96 Mg ha-1 and 1.29 kg m-3 in CEVAMEX 4.76 Mg ha-1 and 0.5 kg m-3; the Atziri Puma hybrid stood out with 6.52 Mg ha-1 and 1.09 kg m-3. No significant ef fect of planting density was observed and D1 resulted with 5.32 Mg ha-1 and 0.9 kg m-3 versus D2 with 5.40 Mg ha-1 and 0.9 kg m-3. In fertilization F1 was statistically higher with 5.64 Mg ha-1 and 0.94 kg m-3. Nevertheless, no dif ference was observed between F2 (5.24 Mg ha-1 and 0.88 kg m-3) and the control F3 (5.19 Mg ha-1 and 0.87 kg m-3), which showed the interaction of the environments with hybrids, of which Atziri Puma stood out at FESC-UNAM (7.3 Mg ha-1 and 1.58 kg m-3). The FESC-UNAM site has productive potential under rainfed conditions with the Puma and INIFAP hybrids.

The cultivation of blue agave has economic importance in the state of Jalisco as it generates employment, being the main economic source in several municipalities such as Tonaya and Tuxcacuesco. However, at present, the edaphological status of the soils is unknown and there is limited knowledge on the factors that regulate crop growth, which limits the determination of optimal crop yields. In this sense, the aim of our research was to evaluate the state of fertility of the soils cultivated with blue agave in plots with different characteristics (virgin and with several planting cycles), as well as to diagnose their status in the Tonaya and Tuxcacuesco municipalities in order to suggest more efficient management and nutrition practices. After analyses in the laboratory, the results show that the soils presented a mean pH value of 7.7, the mean concentration of organic matter was 2.19%. Overall deficiencies of nitrogen, phosphorus and potassium were found, thus, the soils were classified in the low‑to‑poor category in terms of nutritional content. Moreover, there were no significant differences between the plots evaluated, organic matter content and nutrients. We recommend the use of organic fertilizers and bean/corn/agave polyculture when agricultural and economic resources are sufficient.

The Mixteco River basin is located in the state of Oaxaca, Mexico and comprises a total area of 6 559.20 km2, which shows a strong degradation of its natural resources, derived mainly from anthropic actions associated with poor management of its natural resources. Thus, the goal of this research is to evaluate the runof f behavior with the SWAT (Soil and Water Assessment Tool) model in the Mixteco River basin using the soil spatial distribution from INEGI (Instituto Nacional de Estadística y Geografía) and that obtained through technique of DSM (Digital Soil Mapping) technique. The modeling with INEGI (ModINEGI) corresponds to the soil map of the series II scale 1:250 000, and the modeling with DSM (ModDSM) was obtained from the environmental covariates. The SWAT model performance evaluation indicators during the calibration phase were R2 = 0.88 and NSE = 0.87 for ModDSM and R2 = 0.85 and NSE = 0.85 for ModINEGI. However, during the validation period, the ModDSM results (R2 = 0.83 and NSE = 0.81) were better than those of ModINEGI (R2 = 0.83 and NSE = 0.61). Therefore, the results indicate that the spatial variation of the soil types obtained through the DSM technique in combination with the vegetation cover and the distribution of slopes at the basin level, allow the SWAT model to simulate the adequate surface runof f behavior.

The evaluation of the growth of the improved Cobra and Cayman grasses during the first ten weeks of establishment in the rainy season in the tropics are important to estimate the development of the morphological components, because through these elements it is possible to evaluate their potential biomass production available for feed the cattle. The objective of the present study was to characterize the morphological components and their contribution to biomass production at dif ferent weeks of growth of the cultivars Cayman (CIAT BR02/1752) and Cobra (CIAT BR02/1794), hybrids of the genus Urochloa during the rainy season. The cultivars were established during the rainy season and the percentage of emergence, leaf length (LL), leaf width (LW), plant height (PH), stem diameter (SD) and number of shoots (NS) were evaluated. The morphological components were determined by the destructive method, and leaf dry weight (LDW), stem dry weight (SDW) and root dry weight (RDW) were also evaluated. The data were analysed with the SAS statistical program through PROG GLM, the comparison of means was performed by Tukey’s test. The results showed the variables LL, PH, NS and LW were not dif ferent (P > 0.05) among cultivars at dif ferent weeks. On the other hand, for SD there was no dif ference between cultivars. The Cobra and Cayman cultivars had similar responses in the production of morphological components and dry matter production during the growth periods evaluated during the rainy season.

Azospirillum brasilense is a plant growth-promoting rhizobacteria (PGPR) with the potential of being employed as an inoculant to decrease the use of chemical fertilizers. We investigated the ef fect of A. brasilense inoculation on a doubled haploid population derived from Opata / WSHD67.2(257) cross and detected Quantitative Trait Loci (QTL) for seven agronomic traits. The population was segregated, concerning their response to inoculation, into three subgroups: neutral, positive, and negative in a proportion of 60:25:15. A total of 18 major QTL and 83 minor QTL controlled the expression of measured traits. Nineteen QTL showed pleiotropic characteristics; chromosomes 5A, 7A, 7B, and 7D were distinguished as those with QTL controlling four of the seven phenotypes measured. The sequences of nearest markers to major QTL detected synteny to rice sequences that codified for at least 38 candidate genes described and discussed as a first step to understanding the interaction of wheat with A. brasilense.

Aquaponics is a complex food production system where fish and vegetables are produced simultaneously. Microorganisms, fish and plants participate in it; it is a complex system where conditions conducive to fish may not be suitable for microorganisms and plants. The diameter of the substrate particles for plant support and space for microorganism colonies can be a determining factor in aquaponics. This research investigates the particle size of tezontle, a porous red volcanic gravel that is used in Mexico for hydroponics and that here it is hypothesized that there is a particle size of this material that favors the growth and yield of plants in aquaponics. The model consisted of the use of 12 containers of 120 L as ponds for fish, and 12 tubs of 240 L for the substrate and a 120 L/min air pump to supply auxiliary oxygenation to the ponds. Three crops were established in each tub: tomato, cucumber, and lettuce. These cultures were transplanted in 3 tezontle diameters: particle diameter less than 1 cm (Æ<1), greater than 5 cm (Æ>5) and 50:50 % (v:v) mixture of both diameters (<1:>5), which constituted the substrate particle diameter treatments. There was no effect of substrate particle diameter on height, stem diameter, and SPAD readings in tomato, cucumber or lettuce plants. Regarding the yield and quality of tomato fruits (firmness, titratable acidity and ˚Brix) there were also no effects of the particle diameter of the substrate. There was also no effect of treatments on the morphological and quality variables of cucumber fruits. In the final fresh weight of lettuce, the treatment with substrate with diameter <1 cm was statistically superior to diameter >5 cm with averages of 89.87 g and 50.12 g respectively. Particle diameter does not affect the yield or quality of established crops, however, in practical terms the fine substrate < 1 cm is recommended because it has greater moisture retention capacity and greater surface area for bacteria to colonize the environment, and promote higher plant growth and fruit quality in aquaponics. The fine substrate acts as a filter to retain suspended solids and prevents clogging of the system, and improves water quality and generates better living conditions for fish.