Tropical and Subtropical Agroecosystems

Publications
The inheritance of number of pods per plant, number of days to flowering and plant height in okra was investigated. Two okra cultivars, namely ‘Kosti’ and the Indian cultivar ‘Pusa Sawani’ were used in this study. The two parents were selfed for three successive generations to fix the characters under study. Crosses were made between the two parents, and reciprocal F1’s, F2’s and all possible backcrosses were derived from the initial crosses. The experiment was carried out at Shambat, Sudan in a randomized complete block design with three replications. Gene effects, heritability in broad and narrow sense, number of effective factors and genetic advance were determined. No reciprocal differences were found between F1 and F2 generation for all the characters studied. Three parameter additive-dominance model utilizing generation means was used to estimate gene effects. The results indicated that most of the genetic variance was accounted for by additive and dominance gene effects, with evidence of epistasis. High genetic variability, high heritability values and genetic gains support the above conclusions regarding the inheritance of these characters.
 
Comparación del crecimiento de Clavibacter michiganensis subespecie michiganensis con el aceite esencial de Limppia palmeri (Derecha) y los antibióticos de estreptomicina y el ácido nalidixico (Izquierda).  
Las plantas producen compuestos con propiedades antimicrobianas que pueden ser empleados en el combate de diferentes enfermedades en la producción de hortalizas. Con la finalidad de buscar alternativas naturales para el control de la bacteria Clavibacter michiganensis subespecie michiganensis, se evaluó la actividad antibacteriana in vitro de 19 aceites esenciales, de los cuales fueron seleccionados 6 por su actividad bactericida. La técnica utilizada para el análisis de la actividad antimicrobiana fue la de difusión en agar, utilizando discos de papel filtro estériles embebidos con el aceite esencial, diluidos 1:1, 1:5 y 1:10 (v/v), en medio de cultivo específico (NBY) previamente inoculado con la cepa de estudio. El análisis de varianza mostró que existe diferencia significativa (p
 
Composition (%) of the range forages consumed by the experimental animals
Composition (%) of the supplemental diets
Twenty cows gestating Bunaji cows, balanced for their weight and parity, were submitted to four treatments: T1, range grazing, (RG); T2, RG + 100% corn bran (CB); T3, RG + 60% CB + 40% palm kernel cake (PKC), and T4, RG + 60% CB + 40% dried brewer’s grains (DBG) in an on-farm experiment in a complete randomized design. Mean milk offtake (kg/day) at 3 months, 6 months and weaning were lower (P < 0.05) in  cows on T1 than T2, T3 and T4 (0.60 vs. 0.77, 0.93 and 0.95), (0.41 vs. 0.52, 0.60 and 0.62) and (0.26 vs. 0.33, 0.41 and 0.43), respectively. Mean milk yields at 3 months, 6 months and weaning, 4% FCM and total milk yield throughout lactation were superior (P < 0.05) in T3, T2 and T4 compared to T1 (2.91, 3.16 and 3.29 vs. 2.53 kg/day), (2.53, 2.68 and 2.68 vs. 2.29 kg/day) and (2.16, 2.28 and 2.31 vs. 1.79 kg/day), (3.22, 3.48 and 3.59 vs. 2.57 kg/day) and (532.66, 577.29 and 591.31 vs. 435.94 kg), respectively. Among the supplemented cows, the above  mentioned milk parameters were lower (P < 0.05) in T2 and  higher in T4. Time to peak milk production and milk constituents were similar (P > 0.05) among the treatments. Total milk offtake and peak milk production significantly varied among the treatments; the rank order  was: T1 < T2 < T3 < T4 (all P < 0.05). Milk yield was largely an inverse linear function of month of lactation (r = -0.98, P < 0.001). Results indicate that strategic supplementary feeding of pregnant cows in an on-farm situation will improve the  lactation performance of  cows, and quality of concentrates used as supplement should be prioritized
 
Cattle herd size and structure of agropastoralists in the study area
Seasonal occurrence of major diseases of cattle in the study area
A survey was conducted by the administration of structured questionnaires to agropastoralists in fifty settlements in the derived savannah of South-west Nigeria in other to highlight the management practices and some of the factors influencing production in the area. The production system is traditional with animals being maintained on free range grazing, browsing and offer of crop-residues. Rangelands were, however, the major source of feed for the cattle. Farmers rarely supplemented their stock with concentrate diet while the most commonly purchased feed supplement was salt. Cattle constituted the major ruminant in the stock (65%) while sheep and goats accounted for 23% and 11%, respectively. The most favoured and dominant breed of cattle in the agropastoral herd is the Bunaji (White Fulani) (72.10%) followed by N’Dama (18.20%) and Keteku (9.30%). Female cattle were more in the herd than the male for all the breeds. Labour allocation among the agropastoralists is based on sex with more male tasks than female. All the agropastoralists (100%) inherited there stock while few (24%) engaged in care-taking of animals for others. Low milk production, soil-eating and diarrhoea were the prevalent diseases among the animals. Majority (84%) of the agropastoralists depended on the use of local herbs and self medication for treating their animals as against a few (6%) engaging the services of the veterinarian. The system under study vividly typifies a traditional smallholder dairy production system characterized by little or not input. Improved feeding, housing and health management will enhance the productivity of the animals.
 
Se evaluó el impacto del manejo ecoturístico en el área de la reserva ecológica Agua Selva en Tabasco, México. Se determinaron los cambios forestales desde la implementación del proyecto “Agua Selva” y su impacto en la conservación de la selva. También se analizaron los cambios socioeconómicos y la percepción que los participantes del proyecto tienen del ecoturismo. Para el análisis de los cambios forestales se utilizaron imágenes de satélite tipo Landsat correspondientes al sensor MSS y TM de 1976 y 2000, cartografía del INEGI y planos ejidales. La implementación del ecoturismo en la zona ha tenido efectos positivos y negativos. Aunque el proyecto ecoturístico no revirtió la desaparición de los bosques, la tasa de deforestación general encontrada fue de 0.49%, la cual es inferior a las reportadas en otras zonas del estado de Tabasco con orografías semejantes en el mismo periodo de tiempo. En los últimos 15 años, ha tenido lugar un cambio positivo de actitudes hacia el ecoturismo, ya que esta actividad representa una fuente de ingresos cada vez más importante para los habitantes de la zona. Sin embargo en zonas específicas, el ecoturismo también ha provocado conflictos sociales. La participación comunitaria es muy baja generando problemas en el manejo de la actividad ecoturística. Por ello, se recomienda que se vinculen todos los proyectos agropecuarios y sociales para lograr mayor participación de la comunidad y una disminución de los riesgos en el desarrollo del ecoturismo. Es ineficaz implementar proyectos aislados o particulares debido al alto riesgo que implican.
 
Allometric biomass equations for three major forest types with mean and confidence interval bounds. 
Relations to project a as a function of B for several biomass studies. 
Goodness of fit statistics for the conventional allometric model fitted at the species scale. 
Tree biomass plays a key role in sustainable forest management since it is the basis for estimating stocks and fluxes of several biogeochemical elements, the amount of energy stored in biomass, and other conventional goods and services. The most common mathematical model takes the form of the logarithmic equation where biomass is estimated as a function of diameter at breast height with the scaling coefficients a and B. In this study, I answered the following questions related with the allometric model: a) Is it important to develop biomass equations at the species scale or at the site-specific scale?; b) What is the least number of data required for fitting an allometric equation?; and c) Is it possible to develop allometric equations with few or null biomass data without loosing accuracy in biomass estimation? I employed a biomass data source collected in northwestern Mexico for nine different forest species, collected in six different sites from southern Chihuahua to southern Durango, Mexico to answer these questions. Results showed that by fitting site-specific biomass equations there is a net gain of 5% and close to 20% in the coefficient of determination and the standard error, respectively in contrast to fitting an equation at the species level. The minimum number of observations needed is 60 harvested trees to calculate parameters with the least variance and with high consistency. I present two alternate restrictive methods of biomass estimation: a) restricting the number of harvested trees to three to fit equations available in the scientific literature and b) a non-destructive model to fit equations with the same level of accuracy that display conventional allometric models. Both methods estimate biomass within the confidence bounds imposed on the B coefficient of the conventional allometric model.
 
The wild edible tubers, rhizome, corm, roots and stems were consumed by the tribal Valaiyans of Madurai district, Western Ghats, Tamil Nadu were analysed for proximate and mineral composition, starch, vitamins, in vitro protein (IVPD), in vitro starch (IVSD) digestibility and certain antinutritional factors. The tubers of Kedrostis foetidissima and stem of Caralluma pauciflora contain higher contents of crude protein. The tubers of Decalepis hamiltonii and stems of Caralluma adscendens var attenuata and C. pauciflora contain higher contents of crude lipids. All the presently investigated wild edible plants appeared to have a higher level of iron content compared to Recommended Dietary Allowances (RDA) of NRC/NAS (1980) for infants, children and adults. The tubers of Cissus vitiginea, Dioscorea pentaphylla var. pentaphylla, D. oppositifolia var. oppositifolia, D. spicata, D. tomentosa, Kedrostis foetidissima, Parthenocissus neilgherriensis, in the corm of Colocasia esculenta, in the rhizome of Canna indica and in the root of Ipomoea staphylina were formed to contain more starch. The tubers of Cycas circinalis, Cyphostemma setosum, D. oppositifolia var. oppositifolia, Dioscorea pentaphylla var. pentaphylla, Kedrostis foetidissima, Parthenocissus neilgherriensis, and in the stem of Caralluma pauciflora were found to be higher niacin content. All the investigated samples in vitro protein digestibility (IVPD) was found to be low. Antinutritional substances like total free phenolics, tannins, hydrogen cyanide, total oxalate, amylase and trypsin inhibitor activity were also investigated.
 
Values of atom % 15 N excess of shoots of three Arachis pintoi ecotypes inoculated with native strains a) or 
Proportion of nitrogen fixed by Arachis pintoi ecotypes with a) and b) non-nodulating A. hypogaea, or c) and d) average of three grasses as reference plants and two Bradyrhizobium strains, during five harvests. SED represents standard error of difference. 
Amount of nitrogen fixed by three Arachis pintoi ecotypes using non-nodulating Arachis hypogaea a) or the average of three grasses b) as reference plants, and two Bradyrhizobium strains. Cumulative values over five harvests. SED represents standard error of difference. 
The nitrogen derived from N2 fixation was measured by the 15N isotope dilution method, in three Arachis pintoi (Ap) ecotypes: CIAT 17434, 18744 and 18748, using a Bradyrhizobium strain (BS) CIAT 3101, and native strains (NS) from Veracruz, Mexico, on greenhouse conditions. The reference plants were: a non-nodulating Arachis hypogaea, Brachiaria arrecta, Brachiaria brizantha and Cynodon nlemfuensis. Plant material received a 15N-enriched solution at 5 atom % 15N. Five harvests were done, where dry matter yield was highest (Pï‚£0.001) in Ap ecotypes+BS (53.9 ±5.2 g pot-1), vs Ap ecotypes+NS (19.7 ± 0.7 g pot-1). N yield (mg pot-1) of Ap ecotypes+NS was: 439 ± 19.6 mg pot-1 vs 1538 ± 117.0 mg pot-1 (Pï‚£0.001) from Ap ecotypes+BS. Values of atom% 15N in excess of legume shoots were lower (0.027 ± 0.01) with BS, compared to NS group (0.052 ± 0.002). The proportion of N2 fixed was greater than 0.5 in the three Ap ecotypes+ BS, using grasses as reference plant. Arachis pintoi ecotypes CIAT 17434 and CIAT 18744 fixed more N than ecotype CIAT 18748; and the improved Bradyrhizobium strain CIAT 3101 was more efficient to fix N2 than the native strains.
 
Feather mite Megninia ginglymura , Megnin 1877 (Arthropoda, Arachnida, Acari, Astigmata, Analgidae), from back yard turkeys in the Oaxaca ́s Mexico, coast; In vivo observation by computer optical microscopy with 200X lens. 
Northern fowl mite Ornithonyssus sylviarum , Canestrini and Fanzago 1877 (Arthropoda, Arachnida, Acari, Mesostigmata, Macronyssidae), from back yard turkeys in the Oaxaca ́s Mexico, coast; In vivo observation by computer optical microscopy with 200X lens. 
Poultry red mite Dermanyssus gallinae , De Geer 1778 (Arthropoda, Arachnida, Acari, Mesostigmata, Dermanyssidae), from back yard turkeys in the Oaxaca ́s Mexico, coast; In vivo observation by computer optical microscopy with 200X lens. 
To describe the parasitic mites in backyard turkeys, was did this work. The mites were obtain by hand for 30 backyard turkeys in Oaxaca’s Coast region, Mexico; the mites were mount in adhesive paper and wash with the 200X lent in a computer optical microscopy, the parasites size were determinate in the pictures obtained by the microscopy software, the images were sized using a specialist software for it, which relate the number of pixels in the picture with the size of the observation field. Were indentified the species Dermanyssus gallinae, Megninia ginglymura and Ornithonyssus sylviarum, the last two described for first time in backyard turkeys in Mexico. Â
 
Physico-chemical characteristics of soils from Kibera and Maili Saba 
HThe effects of heavy metals lead (Pb), Cadmium (Cd) and Cromium (Cr) on nematode communities and earthworm density and biomass were studied in the wastewater irrigated farms of the Nairobi river basin. The levels of Cr and Pb in the wastewater were below the threshold values considered to be toxic while those of Cd exceeded the permissible limit. Heavy metal accumulation in soils in the Kibera and Maili Saba farms were Cd (14.3 mg kg-1), Cr (9.7 mg kg-1) and Pb (1.7 mg kg-1) and 98.7 mg Cd kg-1, 4.0 mg Cr kg-1 and 74.3 mg Pb kg-1, respectively. High heavy metal concentrations as well as soil organic matter were negatively correlated with plant feeding nematodes in the genera Criconema, Meloidogyne, Paratylenchus, Pratylenchus and Scutellonema. Bacterial feeding nematodes genera Rhabditis, Plectus, Cephalobus and Acrobeles were predominant in the gardens treated with wastewater. An average density of 198 m-2 earthworms and a biomass of 68 g m-2 and 102 earthworms m-2 with 33g m-2 biomass were recorded in Kibera and Maili Saba, respectively. The earthworms isolated from both sites were all epigeic with the metal content in Maili Saba suppressing their populations. This study has demonstrated that the use of untreated urban wastewater for irrigation has adverse effects on nematode and earthworm abundance and diversity and their potential as bioindicators of heavy metal presence.
 
The objective of this study was to estimate the breed-direct, breed-maternal and heterosis effects from data obtained for weaning and yearling weights of Brahman and its crosses with Charolais, Simmental, Brown Swiss breeds in a beef herd in Tabasco, Mexico. The climate of the region is tropical humid. Data were obtained on 1217 calves born from 1995 to 2007; among the 16 breed-group combinations one was purebred mating (Brahman), 3 two-breed static crosses, 7 three-breed static crosses and 5 backcrosses. Cows were fed in paddocks of Jaragua grass (Hyparrenia rufa) of poor condition and invaded with native grass of Paspalum and Axonopous genera. Calves remained with their dams until weaning. They were weighed at weaning and about one year of age. Calve weights from the record cards kept at the ranch were used to calculate adjusted weaning (W240) and yearling weights (W365). During the 13 year period of data collection, 711 cows and heifers were inseminated with semen of 23 Charolais (Ch), 50 Simmental (Si), 19 Brown Swiss (BS) and 15 Brahman (Br) unrelated sires. Also 32 Br bulls were used for natural mating. A multiple regression procedure was used to obtain estimates of the breed-direct, breed-maternal and direct heterosis effects for W240 and W365. The overall means and standard errors for W240 and W365 were 178.5+0.89 and 219.9+1.78 kg, respectively. The analysis of variance showed significant (P0.20) for W365. Except for the Si x Br negative heterosis value for W240, all heterosis effects were positive but nonsignicant (P>0.12).
 
Evolution of the volume of gas produced (mL gas g -1 DM) by cecal fermentation of cellulose in Mexican hairless (○) and Mexican cuino (●) pigs or starch in Mexican hairless (□) and Mexican cuino (■) pigs.  
In vitro cecal gas production of Mexican hairless pigs and Mexican cuino pigs with addition of cellulose and starch at different inclusion levels.
In vitro cecal gas production with addition of different levels of starch in Mexican hairless and Mexican cuino pigs
The objective of the present study was to evaluate and compare the in vitro cecal fermentation (by the gas production technique), in hairless Mexican pig and Asian pig, adding cellulose or starch as a substrates (0, 100, 200, 30 and 400 mg/ g DM). 12 pigs were slaughtered ( BW= 104±0.5 kg), six of each genotype, and after that take cecal content of each one, and it was made a pool using two pigs per genotype; after that per substrate (cellulose or starch) in each concentration, it were incubated in three flasks per pool with inoculums and it made three incubation series. The experimental design use the effect of genotype, substrate and concentration of the substrate added on the variables of in vitro fermentation. The averages of the data were compared by turkey’s method. In vitro gas production was higher (P
 
In the humid tropic of México, there are planted 2.5 million hectares of corn with yield of 2.0 tons per hectare. In this area the corn stunt disease has caused damages greater than 25 % in commercial planting in Yucatán and Veracruz states and the coast region of the Gulf. The objectives of this research were to know the yield and agronomic characteristics of tropical corn genotypes and to identify those well adapted and tolerant to corn stunt disease, Thus, during the spring summer season in 2005/05, there were carried out experiments of maize genotypes, in Medellín de Bravo, Tlalixcoyan and Ignacio de la Llave in Veracruz State, under a randomized complete block design with 10 entries and two replications in plots of eight rows 10 m long and 80 cm wide, for getting 62 500 plants ha-1. The agronomic traits registered were: grain yield, percentage of damaged plants and ears for corn stunt and severity of damage. From the combined analysis for all traits registered, there were found high significant differences for genotypes (G) and locations (L). For interaction GxL, except for percentage of damaged plants, there were found high significant differences for the others traits. The genotypes that had the best yield, agronomic characteristics and tolerance to corn stunt were: H-520, H-513, H-518 and C-343.
 
Proximate composition of water hyacinth meals (WHMs)
Growth performance and nutrient utilization of C. gariepinus fed SBM and WHM based diets
Water hyacinth meal (WHM) as an alternative protein source was investigated in this study. Whole water hyacinth plant meal (WPM), water hyacinth leaf meal (WLM) and soya bean meal (SBM) were used to compound three isoproteic (40% crude protein) fish diets. Catfish of 11.2 ± 0.3g average weight were used for the 70-day digestibility study. Data were collected forthnightly on fish growth performance and water qualities (dissolved oxygen, pH, ammonia and temperature). Fish, feeds, and faecal wastes were analyzed. Fish fed SBM-based diet had superior performance over those fed WHM-based diets with respect to Mean weight gain (MWG), Specific growth rate (SGR), Protein efficiency ratio (PER), Feed conversion ratio (FCR), Nitrogen metabolism (Nm) and digestibility coefficients (ADC). Fish fed all diets exhibited marginal difference in total feed intake but growth performance and nutrient utilization were significantly higher in fish fed WLM than fish fed WPM probably as a result of high fibre content present in WPM. Extremely low value of ammonia was recorded in water under WPM treatment (0.18±0.06 mg/l) while water under WLM and SBM treatment had significantly higher values of ammonia 0.46± 0.13 mg/l and 0.71± 0.10 mg/l respectively. These observations may be due to the presence of significantly higher fibre content in the WPM than other meals. Consequently this could be responsible for its poor digestibility values but high potential for waste water purification. Water hyacinth leaf meal (WLM) would therefore serve a better option for adoption in ensuring maximum utilization potentials of the aquatic plant both for profitable and sustainable fish production.
 
p> Background. The Macrobrachium tenellum prawn is captured and commercialized by local fishermen along its distribution interval. It is considered an euryhaline palemonid prawn. If its cultivation is wanted, the best conditions for its growth and reproduction should be investigated, including proper intervals of temperature, salinity, density and dissolved oxygen. Objective. To determine the effect of two different salinities (0 and 15PSU) on the physiological rates that balance the energy equation in M. tenellum adults and to determine if energy use is more efficient under isosmotic conditions. Methodology . Specimens were collected in Guasave, Sinaloa, Mexico, in July 2018 and taken to the Aquaculture Laboratory at UAdeO. The energy balance was calculated in hyposmotic (0 PSU) and isosmotic (15 PSU) conditions at preferred temperature (28.5 ± 1 ° C). The energy invested in respiration and excretion, the feces lost and the ingested food and the growth potential was calculated using a semi-open respirometer. Results. The highest energy expenditure occurred in the respiratory rate (routine metabolism), then feces production and finally ammonia production in both salinities. The highest total energy expenditure was observed in fresh water. The highest amount of energy directed to the growth or reproduction was observed in brackish water (15 PSU), as well as the highest rate of food ingestion. Implications. Knowledge on the use of energy in the feed in the best saline condition for its cultivation useful for culture purposes. Conclusion. The saline condition in where more energy is channeled for the growth of M. tenellum is 15UPS (isosmotic point) and in it is also in where less energy is spent.</p
 
Alternative techniques and methods of agricultural production that enhance the use of genetic resourses for a nutrition-sensitive agriculture for health.
p> Background: The COVID-19 pandemic evidenced the fragility of the agri-food sector by affecting the food supply chains which directly depend on the health of its main actors. In this context, countries need to rethink the agricultural production models, considering environmental and human health as priorities to achieve food safety. Aim: Systematically review the state of the art regarding the role of agricultural genetic resources as a source of resilience in the face of events such as the present pandemic as a point of reflection for the identification of opportunities for the restructuring of regional agriculture sensitive to nutrition for health. Methodology: Exhaustive search and analysis of documentary information regarding the effects of COVID-19 on the agri-food sector and the role of agricultural genetic resources in the current pandemic were conducted. Then, through an analysis of the occurrence and association of the main terms addressed in the literature considered, the thematic axes were drawn to address the central discussion of the systematic review. Results: Terms co-occurrence analysis corroborated the relevance and pertinence of the topic addressed. Additionally, the importance of the conservation of agricultural genetic resources and implementation of sustainable agriculture models, as a source of resilience to pandemics, was visualized. The discussion addressed the impact of the pandemic on the Mexican agri-food sector and the restructuring of post-COVID-19 agriculture through the nation and nutrition-sensitive agriculture for health approaches. Implications: The exhaustive analysis of the relationship COVID-19-agricultural genetic resources-health in Mexico highlights the need for the generation of agricultural policies and the increase in multidisciplinary research that favors biodiversity as a source of sustainability, productivity, and health for agroecosystems and the welfare of humanity. Conclusions: A fatalistic scenario for humanity seems to be dissipating in the face of the possibilities of rethinking the economic, social, and agricultural systems from the approaches of the nation and nutrition-sensitive agriculture for health, where, through the responsible use of agricultural resources it is possible to rebuild an agri-food production system with a tendency to resilience to events such as the current pandemic caused by the COVID-19 disease.</p
 
Infestación de Tetraleurodes ursorum Cockerell, 1910 en las hojas (a), brotes en desarrollo (b) y frutos (d), e incidencia de fumagina en las hojas (c) y en el fruto (d).
p> Background: In Mexico, 164 species of whiteflies have been reported in different crops, among which are citrus varieties. Objective: In the present work, the whitefly species was identified and determined the population size of the nymphal state and adults in citrus trees. As well as, the severity of the sooty mold ( Capnodium citri ) in the leaves and fruits was quantified in a citrus orchard in the municipality of Victoria, Tamaulipas, Mexico. Methodology: Nymphs and adults of the whitefly were sampled in the citrus trees selected at random in a 500-hectare orchard. The specimens were identified with taxonomic keys of the whitefly species. Then, the size of the nymphal and adult population of the identified fly species was determined, and the percentage of severity of sooty mold in the leaves and fruits was quantified. Results: In the orchard, the whitefly species present on the trees was identified as Tetraleurodes ursorum Cockerell, 1910. Of this species, more than 75 adults were recorded on the leaves and fruits per tree, and an average of 20 nymphs per developing shoot per tree. In the case of the severity of C. citri , this was greater than 80% in 95% of the fruits and leaves per tree. Implications: The results of this study are very useful for the development of sampling and control strategies for T. ursorum that help prevent the spread of this pest insect in the citrus zone of Tamaulipas state. Conclusion: Based on the results, the focus of T. ursorum infestation in the study area represents a risk for citrus production in the municipality of Victoria, Tamaulipas. Said infestation may be related to the presence of insect host weeds, and possibly to the biological control of the pest insects and to the organic management of some citrus varieties in the orchard.</p
 
Aleurocanthus woglumi is present in Paraíba state since 2009, causing a lot of damage to the citrus production in the State. There is a lack of knowledge about the bioecology of this Aleyrodidae member under the climatic conditions of Paraíba State. Thus, in order to know the population density of the pest and study the interference of climatic factors upon these insects, yellow sticky traps were installed evenly distributed in the orchard in the agroecological citrus property in Areia city, in Paraiba state. There were two distinct population peaks of the pest, one in September 2011 and another in April 2012. The lowest densities of the pest were recorded between October and December 2011, a period in which there was no new budding. The population monitoring of A. woglumi in Paraiba state has allowed knowing the time in which the insect occurs in the orchard and the variations in the number of individuals throughout time.
 
We have made a review on the status of Litopenaeus vanname in culture in low salinity water, presenting particularity, advantages, disadvantages and mitigation measures on the environmental impact of this culture system. This paper describes relevant issues in order to draw a path to sustainability of this alternative crop that is expanding rapidly in Mexico.
 
OLS showing effects selected variables on TFP
This study examined changes in agricultural productivity in Sub-Sahara Africa countries in the context of diverse institutional arrangements using Data Envelopment Analysis (DEA). From a time series which consists of information on agricultural production and means of production were obtained from FAO AGROSTAT and rainfall data from Steve O'Connell data base. The information was for a 43-year period (1961-2003); DEA method was used to measure Malmquist index of total factor productivity. A decomposition of TFP measures revealed that the observed increase in the TFP in the sub-Sahara Africa agriculture is due to technological change rather than efficiency change which is the main constrained of achieving higher level of TFP during the reference period. The study further examined the effect of land quality, malaria, education and selected governance indicators such as, control of corruption and government effectiveness on productivity growth. All the variables included in the model are significant with the exception of government effectiveness.
 
p> Background: Dairy industry economics and public health are negatively impacted when udder health is compromised. Intramammary infection is the most important infectious problem generating economic losses to the milk production systems around the world. Affectations of animal generated diseases on public health are well known. Several categories of analysis have been studied to implement prevention and control strategies against intramammary disease. However, the control of these affectations has been considered a complex problem based on various factors. Objective: characterize the categories and subcategories of analysis used for the study of udder health published in research papers during the period comprehend between 1962 - 2019. Methodology: A systematic review with a broad approach in the research protocol was designed applying the identification phases, screening, choice, and inclusion criteria described in the PRISMA guide. A qualitative synthesis of year of publication, continent, focus, category of udder health analysis, and subcategories of udder health analysis was performed. Results: We found that more than half of the papers identified in this topic were published in the last decade of the studied period (1962 - 2019). New categories were incorporated into the timeline, evidencing an evolution in the way of understanding udder health problems. Implications: Many of the countries that publish most of the papers have implemented programs and policies on udder health management in recent years. Precisely in the last decade, cultural processes and political processes were incorporated into the study of udder health. This incorporation of new and relevant topics may have been very useful in the design and evaluation of public policies on udder health in those countries. Conclusions: These results show the interest in the academic, productive, and political sectors for udder health and its consequences on public health.</p
 
In Mexico, poor crop rotation has affected the capacity of soil to produce; the use of maize genotypes with higher yield potential and more intensive production systems has increased the demand for inputs, which affects the economy of the producer. To determine the effect of changes in input prices and the main factors that explain the supply of maize grain in Guanajuato, in the present work an econometric model was estimated; comprised of two supply equations, three transmission prices and an identity for the period from 1980 to 2009. The results indicate that the supply of maize grain in the state responds inelastically to changes in the producer price of maize produced under irrigation and elastically if changes arise in the same price level but the offer temporary, with elasticities own-price 0.8531 and 1.0604, changes in input prices that more affect the state offer are the pesticide and labor price, with cross-price elasticities of -0.6154 and -0.5470, changes in the competitive product that more impact are those in the bean, with cross-price elasticities of -0.5489, if produced under irrigation and -1.0292 if produced in temporary. The effect of price transmission, indicate that the producer price of maize under irrigation and temporary state is directly influenced by the wholesale price at a rate of 0.79 and 0.80% for each 1% change in it, while the cost of transport and the international price of maize influence on the wholesale price in the state at levels of 0.21 and 0.13% for every unit percentage change in them.
 
In Mexico, poor crop rotation has affected the capacity of soil to produce; the use of maize genotypes with higher yield potential and more intensive production systems has increased the demand for inputs, which affects the economy of the producer. To determine the effect of changes in input prices and the main factors that explain the supply of maize grain in Guanajuato, in the present work an econometric model was estimated; comprised of two supply equations, three transmission prices and an identity for the period from 1980 to 2009. The results indicate that the supply of maize grain in the state responds inelastically to changes in the producer price of maize produced under irrigation and elastically if changes arise in the same price level but the offer temporary, with elasticities own-price 0.8531 and 1.0604, changes in input prices that more affect the state offer are the pesticide and labor price, with cross-price elasticities of -0.6154 and -0.5470, changes in the competitive product that more impact are those in the bean, with cross-price elasticities of -0.5489, if produced under irrigation and -1.0292 if produced in temporary. The effect of price transmission, indicate that the producer price of maize under irrigation and temporary state is directly influenced by the wholesale price at a rate of 0.79 and 0.80% for each 1% change in it, while the cost of transport and the international price of maize influence on the wholesale price in the state at levels of 0.21 and 0.13% for every unit percentage change in them.
 
In 2008 Mexico ranked as the second worldwide producer (14.94%) of lemons and the first of exportation (20.5%), principally of persian lime; so that the objective of the research was to identify and assess those factors that determine the demand of importations of persian limes in the United States, principal market destiny (94.7%). Under the assumption that this market offers a real capacity for expansion of Mexican producers of this crop, was formulated a multiple regression model, considering the income, exchange rate (peso / dollar), unit import price and the demand of importations, estimated by the method of Ordinary Least Squares (OLS), with annual data from 1994-2008, also obtaining the elasticities of demand. The highest response was variable income with an elasticity of 3.8, classifying the Persian lime as a normal top, followed by the exchange rate (0.83) and price (-0666). It was concluded that it is feasible to maintain the current growth rate of demand for imports from Persian lime, of 9.3% annual average, because the required increase in real U.S. income would be 2.45% (ceteris paribus), for 2.9% growth observed in the study period.
 
In 2008 Mexico ranked as the second worldwide producer (14.94%) of lemons and the first of exportation (20.5%), principally of persian lime; so that the objective of the research was to identify and assess those factors that determine the demand of importations of persian limes in the United States, principal market destiny (94.7%). Under the assumption that this market offers a real capacity for expansion of Mexican producers of this crop, was formulated a multiple regression model, considering the income, exchange rate (peso / dollar), unit import price and the demand of importations, estimated by the method of Ordinary Least Squares (OLS), with annual data from 1994-2008, also obtaining the elasticities of demand. The highest response was variable income with an elasticity of 3.8, classifying the Persian lime as a normal top, followed by the exchange rate (0.83) and price (-0666). It was concluded that it is feasible to maintain the current growth rate of demand for imports from Persian lime, of 9.3% annual average, because the required increase in real U.S. income would be 2.45% (ceteris paribus), for 2.9% growth observed in the study period.
 
-Technological practices in goats in GGAVVAT Caprinocultores Unidos de Guanajuato. 
Productive parameters of rearing and production of the Association Caprinocultores Unidos de Guanajuato. 
The aim of the study was to analyze the effect of technology adoption on milk goat producers in central México. The association has 13 producers, with an average age 41.5 years old, the average schooling reaches junior high school (3rd year), and  a mean of 6 dependants per family. This association has an average number of 246 female goats per herd, a total of 3447 females, and 2190 females in production control. The income in relation to investment is 36%. Technological practices implemented to date and the percentage of use are: Weighing milk (100%), Animal Nutrition consulting (71%), Estrus synchronization and reproductive management techniques (40%), Gestation Diagnosis (93%), Brucellosis control herd program (100%), Artificial kids raising in slat (46%), Disease diagnosis and management (61%), Certification of good milking practice (53%), Linear and genetics evaluation (87%) Evaluation of genetic records ( 61%), Forage conservation by silage (93%), Milk components analysis (100%), dispersion of genetic material (71%), Analysis and data processing for replacement selection and animal sale (Sire and females)(100%), Bacteriological analysis of milk (93%), Cryoscopic point of milk (100%), and Diagnosis of subclinical mastitis (cytometryc flow) (100%). An 80% of the producers have adopted different practices, and the association has promoted and implemented different programs such as: control milk production, milk quality, genealogical records, disease control, marketing in group, sales of fluid milk and dehydration of milk for conservation and sale. Accordingly to such practices, results are as follows: 11,180 kids born, from which 52% were females and 48% males, with 56.9%, 24.3%, 15.7% and 2.9% of double, triple, simple and quadruple births, respectively. The mean birth weight was 3.32 kg and 15.7 kg weaning at 60 days, with a daily gain weight (DGW) of 206.33 g. For milk production, 3534 lactations were analyzed from 1999 to 2007 in a 90.4% of animals ranging from 1 to 4 lactations, a 9.58% from 5 to 11 lactations, and 35% of animals in the 1st lactation. An ANOVA was performed under a randomized design considering the effects of lactation number. The lactation number influenced (P
 
Agricultura familiar especializada (AFE).
Agricultura familiar diversificada (AFD).
p> Background: the agricultural production system, its operation, monitoring and execution, requires formulating new evaluation schemes. Integrating the vast majority of social, cultural, ecological, economic, geopolitical characteristics and factors related to the technology applied in production systems. Through the use of associated indicators in each of its dimensions and attributes, to analyze its sustainability. The objective: This research is the evaluation of the sustainability of the production systems of family farming in the Penipe canton. That demands the selection, transformation and aggregation of economic, environmental, geopolitical, cultural and social indicators, which allow determining trends of the system, using a systemic, participatory, interdisciplinary and flexible approach called the MESMIS framework. Methodology: MESMIS was applied to nine representative farms of diversified, specialized and subsistence family farming production system. By determining the critical points, the indicators were applied once standardized and weighted. Results: Specialized family farming production system is sustainable with a score of (1.56), diversified family farming is moderately sustainable with a score of (1.32) and subsistence family farming, with a value of (0.77) is considered an unsustainable system within the locality. Implications: It was found that there are some aspects that limit the farms to be considered as sustainable systems, identifying the attributes to improve. In order to improve subsistence family farming, it is necessary to work on the following parameters: productivity, stability, resilience, reliability, adaptability, equity and self-management; diversified family farming expresses the following attributes to improve: productivity, stability, resilience, reliability, equity and self-management and specialized family farming has to improve in: Productivity, resilience, stability, equity. Conclusions: This evaluation responds to a cyclical process that, by effectively integrating the evaluation in the decision-making process, improves the probability of success in the design of alternatives to improve the productive systems in the Penipe canton.</p
 
Individual ovulatory activity in Alpine, Nubian and Criollo × Nubian female goats maintained under tropical latitude (22 ° N), natural climate and controlled nutrition. Ovulatory activity was discerned from twiceweekly determinations of progesterone by radioimmunoassay. One line represents one female goat. A closed square or rectangle represents one or more than one progesterone measurements above 1 ng/ml of serum, and are considered as indicative of at least one luteal structure or corpus luteum, respectively.
In the present study, seasonal variation in ovulatory activity of Nubian, Alpine and Criollo x Nubian goats in the semiarid region of central-northern Mexico (22° 14' N) was examined. The study was conducted under natural photoperiod and climate conditions during a whole year. Eight female goats per breed were grouped separately and exposed to visual, olfactory and audible signals of bucks. Blood samples were obtained twice per week and serum progesterone concentrations were determined. All goats presented a clear pattern of seasonal ovulatory activity based on serum progesterone profiles. Length of the ovulatory activity period did not differ between genotypes (P >0.10), and had an average duration of 4.3 months. Nevertheless Criollo x Nubian goats presented greater individual variation in dates of onset and end as well as length of this period (P <0.05). Results indicate that female goats of genotypes which differ in latitude of origin, express a similar restricted pattern of seasonal ovulatory activity when subjected to small annual changes in phtoperiod, adequate nutrition and incomplete socio-sexual stimulus.
 
Individual ovulatory activity in Alpine, Nubian and Criollo × Nubian female goats maintained under tropical latitude (22 ° N), natural climate and controlled nutrition. Ovulatory activity was discerned from twiceweekly determinations of progesterone by radioimmunoassay. One line represents one female goat. A closed square or rectangle represents one or more than one progesterone measurements above 1 ng/ml of serum, and are considered as indicative of at least one luteal structure or corpus luteum, respectively.
In the present study, seasonal variation in ovulatory activity of Nubian, Alpine and Criollo × Nubian goats in the semiarid region of central-northern Mexico (22° 14' N) was examined. The study was conducted under natural photoperiod and climate conditions during a whole year. Eight female goats per breed were grouped separately and exposed to visual, olfactory and audible signals of bucks. Blood samples were obtained twice per week and serum progesterone concentrations were determined. All goats presented a clear pattern of seasonal ovulatory activity based on serum progesterone profiles. Length of the ovulatory activity period did not differ between genotypes (P >0.10), and had an average duration of 4.3 months. Nevertheless Criollo × Nubian goats presented greater individual variation in dates of onset and end as well as length of this period (P <0.05). Results indicate that female goats of genotypes which differ in latitude of origin, express a similar restricted pattern of seasonal ovulatory activity when subjected to small annual changes in phtoperiod, adequate nutrition and incomplete socio-sexual stimulus.
 
p> Background . In the new global economy, cocoa is an important crop. However, far too little attention has been paid to the nutritional aspects. On the other hand, nitrogen is the most important nutrient in crop production, and mineral nitrogen fertilizers are the most widely used by farmers. Improving the efficiency of nitrogen uptake and utilization could potentially increase crop yields and quality, as well as reduce nitrogen fertilization and environmental pollution. Objective. Therefore, the objective of this study was to evaluate the effect of three nitrogen sources on morphological characteristics, yield and quality of CCN-51 cocoa, and soil chemical characteristics in the Ecuadorian Amazon. Methodology. A randomized design was established with 4 treatments with the same N dose, but varying the source (amide: urea, calcium nitrate, NC, and ammonium sulfate, SA), plus a control without N application. The investigated variables are soil chemical characteristics, shoot growth, fruit morphology, seed chemical characteristics, production and yield estimates, and agronomic efficiency of the sources. Results. NC maintained soil pH at 5.29 points compared to SA and urea, which acidified at a higher rate (4.32 and 3.96), leading to an increase of N and a decrease Ca in the soil. SA increased the fat content in the cocoa seed (54.1 %), with a higher number of fruits per plant (16.7) and, therefore, a better yield (0.799 t/ha). Implications. These results provide basic information on the nitrogen source effects and cocoa nutrition to be considered for future research. Conclusion. The findings suggested that NC conserves soil pH better than the other sources. SA increases production and fat content, so it can be considered the most efficient. </p
 
The influence of time of poultry manure application: no application, at planting, 1, 2 and 3 months after planting (MAP) were determined on the growth, yield and fruit quality of two plantain (Musa spp. AAB) cultivars (PITA 17 and French Reversion). PITA 17 significantly produced more standing leaves, fruits with longer green and shelf life. French Reversion significantly produced taller plants, heavier bunches and fruits, wider and longer fruits. Dry matter partitioning to the pulp, pulp degree of lightness and redness were also higher for French Reversion than PITA 17. The application of poultry manure at 2 MAP produced heaviest bunches and the highest yield components while pulp dry matter and fruit shelf life duration were highest with manure application at 3 MAP. Bunch and fruit weights were heaviest in French Reversion plots applied with poultry manure at 2 MAP whereas shelf life was longest with PITA 17 that received manure application at planting.
 
The influence of time of poultry manure application: no application, at planting, 1, 2 and 3 months after planting (MAP) were determined on the growth, yield and fruit quality of two plantain (Musa spp. AAB) cultivars (PITA 17 and French Reversion). PITA 17 significantly produced more standing leaves, fruits with longer green and shelf life. French Reversion significantly produced taller plants, heavier bunches and fruits, wider and longer fruits. Dry matter partitioning to the pulp, pulp degree of lightness and redness were also higher for French Reversion than PITA 17. The application of poultry manure at 2 MAP produced heaviest bunches and the highest yield components while pulp dry matter and fruit shelf life duration were highest with manure application at 3 MAP. Bunch and fruit weights were heaviest in French Reversion plots applied with poultry manure at 2 MAP whereas shelf life was longest with PITA 17 that received manure application at planting.
 
Livestock activities due to the improper handling of the load capacity, suffer from low productivity in their grasslands, which are abandoned giving rise to the appearance of species considered invasive and undesirable for producers, without knowing the qualities of these as mitigating of climate change. The objective of the present study was to estimate the carbon content in tamaulipan thornscrub and three abandoned grasslands with a time of abandonment of 10, 20 and 30 years. For the estimation of the carbon content was used a systematic sampling design, in each area were established four sampling sites of 1,600 m2. The primary scrub is the system that resulted in the largest value of carbon content of 14.25 Mg ha-1, followed by the grasslands of 30, 20 and 10 years with 8.03, 7.33 and 4.13 Mg ha-1 respectively. It was concluded that recovering the initial state of the primary scrub take many years, as can be seen in the grasslands system 30 years reaching only 56% of what it had in reserves of primary scrub.
 
p> Background. It is undeniable the presence of many other contaminants in the food supply sources, in addition to the pathogens. Objective. The objective of this study was to analyze biogeochemical parameters to evaluate the quality of the water from the applied treatment and at the same time determine the ideal doses of chlorine for the disinfection of the supply waters in Espita, Yucatán. Methodology . The water quality was determined at sample points (i.e. houses in the areas adjacent to supply wells) during the months of August, October, November and December 2019. The biogeochemical parameters sampled were determined based on standardized methods for analysis of drinking water. Results. The free residual chlorine determined in the house-room samples presented lower elevations than necessary (0.10 to 0.25 mg / L) for a residual effect that mitigates the presence of pathogens. According to the comparative analysis, the means of the concentrations of free residual chlorine do not present statistical differences for the four supply wells, which led to a proposed sodium hypochlorite dose of 4.10 and 8.60 mg / L for 0.10 and 0.25 ppm respectively of free residual chlorine. The analysis of the results of the concentrations of ammonia nitrogen (N-NH<sub>3</sub>) showed the existence of recent contamination in the third and fourth samples; for nitrate nitrogen (N-NO<sub>3</sub>), specifically elevated concentrations were also found in the first and second sampling. Implications. This analysis is useful for local decision-makers as data-driven or proposed decisions can improve the provision of the water supply service. Conclusions. The results suggest contamination of the water by external agents, for example, from agricultural products such as fertilizers and wastewater from sumps connected to wells. No free chlorine concentrations were found that promote the residual effect, it is necessary to implement continuous verification.</p
 
p> Background. The diversity and ecology of various groups of insects has not yet been fully studied in Mexico. Objective. Present a review of the contributions to science, which have been made on the diversity and ecology of bees, predatory wasps and butterflies. Methodology. The contributions of scientific articles and book chapters (33) of the Department of Zoology of the Campus of Biological and Agricultural Sciences of the Autonomous University of Yucatán were reviewed. Main findings . There is greater knowledge about the diversity of species including new registers, complementary contributions include ecological topics of the species on the lifestyles or eating habits and nesting sites of the species and there are studies about floral fragrances. In addition, in bees, there are contributions on the temporal variation in diversity, the effects of natural and human disturbances on the diversity of species. Implications. The knowledge generated is essential to establish conservation strategies due to the importance of these insects as key species in ecosystems. Conclusion. The contributions to science are mainly studies on biodiversity, in addition to some contributions from the ecology of the species, which are important for proposals for the sustainable management and conservation of pollinators species, pest controllers, biondicators and for the study of species as a window to climate change.</p
 
Soil pollution reduces yields and food quality. Fitorremediation is a process used to recuperate polluted soils which competes favorably with more expensive physical and chemical methods. Samples of soil and roots of wild plants were collected at nine sites of Colegio de Postgraduados, Campus Montecillo. After determining the pH of soil samples, the supernatant was streaked on solid King's B medium. Root apex samples were macerated and the liquid collected was streaked on the same medium and all the dishes were incubated at 26 to 28 °C. Of 223 bacterial isolates obtained, 23 were selected for producing fluorescent pigments and being safe for plants. Two soil (2S-10, 2S-9) and one root (2R-2) isolates had the most fluorescent pigment production. Alfalfa seeds inoculated with cells of the isolates 2S-10, 2R-2, and 2S-9 germinated 78, 56, and 88 %, respectively, while uninoculated seeds germinated 88 %. A preliminary test highlighted the best development of the inoculated seedlings with the isolate 2S10. Therefore, using plant-microbe interaction is possible to enhance the potential of plants to accumulate metals, making phytoremediation a more efficient process.
 
Data from 2438 calvings born to 682 cows recorded from 2004 to 2015 in an extensive production system were used, to investigate factors associated with abortion and calf mortality until weaning. Cows belonged to Brahman, Nellore, Guzerat and Brown Swiss x Zebu breed groups. Data were analyzed using binary logistic regression, and the statistical model included the effects of year and season of calving (or abortion), parity number, breed group of the cow and sex (only for preweaning mortality). Abortion rate was 0.99% varying from 0.61% to 1.94% among year groups. First parity and Nellore cows had the greatest abortion rates (1.66 and 1.46%, respectively). The calf mortality rate was 9.65%, varying from 3.18% to 14.65% across all years. The major factors associated (P < 0.05) with mortality of calves included year and season of calving, parity number and breed group of the cow. Nellore cows had the highest odds of preweaning mortality (OR=4.41). Cow parity number and season of calving were also associated with calf mortality. First parity cows had the major calf losses overall. In conclusion, closer attention to the management of first parity cows could reduce calf mortality.
 
Chlamydophila abortus (Cp. abortus) is the bacterial etiologic agent of the ovine enzootic abortion; zoonotic relevance rises during handling of ill animals. The present work estimates the prevalence of serum antibodies against Cp. abortus in groups of people at risk of infection derived from working activities, and estimates possible risk factors involve in the infection. A transversal study was conducted in two groups of exposed people. In Group A 86 sheep flock owners or workers were included. In Group B 52 veterinary doctors were included. Antibody titers were determined by rELISA assay, additionally it was asked to people sampled to answer a questionnaire to establish risk factors. Overall serum antibody prevalence against Cp. abortus in both groups was 6.52% (IC95%, 3.02-12.01%). According to the risk group, people from group A was 4.45% (IC95% 1.28 - 11.48) and in group B 9.62 (IC 95% 3.19 - 21.02), according to gender prevalences were 5.07% (IC95% 1.99 - 11.29)and 1.44% for women and men respectively; no differences were found (P>0.05). It is concluded that serum anti Cp. abortus antibody prevalence in relatively low among sheep flock owners, workers and veterinarians and no significant differences were found among possible risk factors.
 
Biomass stocks and their spatial distribution remain poorly understood in tropical forests and reliable estimations are critical in the calculations of carbon stocks and fluxes. This report aims to estimate and contrast aboveground biomass (AGB) stocks in tropical forests of Mexico (classified as dry, moist and rainy) by employing three different evaluation techniques. The first method uses a simple mean biomass density value per each forest class multiplied by the area of each forest. The second approach improves the spatial resolution by classifiying forests per each region and a mean biomass density is multiplied by the area of each forest class. The third methodology calculates biomass stocks by developing an empirical model using mean annual precipitation as the independent variable and then applying the equation to the mean annual rainfall of each tropical forest times the area of the forest. Results showed that all three methods of AGB stock estimations are quite consistent since they have mean (confidence interval) values of 3.0 (0.69), 3.0 (0.30), and 2.25 (0.67) Pg estimated by first, second and third approaches, respectively. Deviations between evaluation methodologies did not surpass 0.45 Pg or 16% of the mean AGB stock. Using all three statistics, mean (confidence interval) aboveground biomass stocks for Mexican tropical forests is 2.77 (0.56) Pg. This statistic deviates by more than one order of magnitude when contrasting it with other six independent AGB estimates. However, the mean figure reported in this study or a mean AGB calculated across all estimation methods provides a dataset that is important for conducting carbon stocks and fluxes for Mexican tropical forests.
 
Relationship between aboveground biomass of different plots estimated from allometric equations and in situ peak LAI measured by LAI-2000 at 1 m canopy height
General tree stand characteristics determined in the study plots.
Mean LAI and standard deviations of LAI taken at the ground level (LAI0), 1M level and 2M levels. Significant differences within each height level are represented by minor letters at α = 0.05
Aboveground biomass of trees and shrubs calculated from species-specific allometric equations and total
Leaf Area Index (LAI) dynamics and aboveground biomass of a semi-arid grassland region in Southern Ethiopia were determined over a long rain season. The vegetation was categorized into four distinct vegetation types namely Grassland (G), Tree-Grassland (TG), Bushed-Grassland (BG) and Bush-Tree grassland (BT). LAI was measured using a Plant Canopy Analyzer (LAI2000). Biomass dynamics of litter and herbaceous components were determined through clipping while the aboveground biomass of trees and shrubs were estimated using species-specific allometric equations from literature. LAI showed a seasonal increase over the season with the maximum recorded in the BG vegetation (2.52). Total aboveground biomass for the different vegetation types ranged from 0.61 ton C/ha in areas where trees were non-existent to 8.80 ± 3.81ton C/ha in the Tree-Grassland vegetation in the study site. A correlation of LAI and AGB yielded a positive relationship with an R² value of 0.55. The results demonstrate the importance of tropical semi-arid grasslands as carbon sinks hence their potential in mitigation of climate change.
 
Tasa de crecimiento relativo (TCR) de cabritos locales en el norte de México obtenida de los modelos Logístico y Gompertz.
p> Background. A growth curve allows us to identify the potential of animals to gain live weight. The growth curve of local goat kids in northern Mexico is unknown. Objective. Characterize the growth curve of local kids using two non-linear models and estimate the absolute and relative growth rates. Methodology. The Gompertz and Logistic models were used to characterize the growth curve and absolute and relative growth rates of the kids. The models were compared using four goodness-of-fit criteria. Results. The growth curve was similar with both models, the kids had mature weights of 62.5 and 58.3 kg with Gompertz and Logistic, respectively, although their maturation rate was slow. The Gompertz model slightly outperformed the Logistic in the goodness of fit. Both models were similar in estimating absolute and relative growth rates. Implications. The high mature weights obtained by the kids suggest a potential to start a dual-purpose production system in the region, which will result in higher income for producers. Conclusion. Local goat kids from northern Mexico mature slowly but reach a high mature weight.</p
 
Root nutrient content (mg plant -1 ) in chile pepper plants as affected by salinity and N rate and source combination treatments. 
The combined effect of salinity and two N sources on content, uptake rate and translocation of nutrients by chile pepper plants (Capsicum annuum L.) cv. Sandia was investigated in a greenhouse experiment. Either an organic-N liquid fertilizer extracted from grass clippings or ammonium nitrate, an inorganic fertilizer, were combined with three different soil salinity treatments (1.5, 4.5, and 6.5 dS m-1). Fertilizer treatments were two rates of organic-N fertilizer (120 and 200 kg ha-1) and 120 kg ha-1 of inorganic fertilizer. The combination of each N rate and source with the three salinity levels were arranged in a randomized complete block design replicated four times. The use of the organic-N source produced greater cation contents (Ca2+, Mg2+, Na+ and K+) in roots, shoots, and enhanced the uptake rates and translocation of cations to shoots compared to plants fertilized with inorganic -N. The root and shoot concentration, uptake rates and root-to-shoot transport of Cl- increased at increasing salinity. Higher contents of Cl- and cations in chile pepper shoots in relation to roots were observed. It was also observed that high N rate from the organic source enhanced the cation contents in both roots and shoots. Salinity diminished N content, N uptake rate and root to shoot transport in both roots and shoots.
 
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Veerabahu Ramasamy Mohan
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Nancy Karanja
  • University of Nairobi
S. Okoth
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V. Vadivel
  • SASTRA University
Carlos A Sandoval-Castro
  • Universidad Autónoma de Yucatán