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

Objective: to determine the dry biomass and quantify the amount of nitrogen and potassium assimilated by Solanum lycopersicum, developed in a sodium saline soil, in response to the application of poultry manure, and sulfur (S °) through fertigation.Design / methodology / approach: The study was modified in 2016, in the municipality of Moctezuma, SLP, in a shade mesh greenhouse, two doses of sulfur were evaluated 750 kg ha-1 (S1) 1500 kg ha-1 (S2 ) and four levels of manure (1, 2, 3 and 4 t ha-1). Three destructive samplings were considered for the calculation of physiological indices, dry matter and the determination of nitrogen and potassium. Fresh product yield and other yield components were evaluated in six harvests. Results: The highest MST production (kg ha-1) was obtained under the S1 treatment throughout the growth cycle. The highest amount of total accumulated N and K in plants, under the S1 treatment, represents 81.8% and 78.6% of the total applied at the end of the cycle; respectively. The highest production in total commercial fresh fruit accumulated, obtained under the treatment of 750 kg ha-1 of sulfur (S1), was 162.9 t ha-1, surpassing the treatment of 1500 kg ha-1 (S2). Study limitations/implications: no specific differences were reported for poultry manure applications. Findings / conclusions: physiological indices and dry matter rate were affected by the application of S1.

Objective: To determine the production of gas, methane and degradation of dry matter in vitro of silage made with pumpkin pulp shell (PPS; Cucurbita argyrosperma), pangola grass hay (Digitaria decumbens) and urea as additives and two inclusion percentages of molasses fermented for 14 and 21 days. Methodology: The silages (2 kg) were: E1= 72.5% PPS, 22.5% pangola grass, 3% molasses and 2% urea; and E2= 72.5 % PPS, 19.5% pangola grass, 6% molasses and 2 % urea. Both silages were fermented for 14 and 21 days. Gas production was evaluated, methane (CH4), total bacteria count and dry matter degradation (DMDEG). The experimental design was a completely randomized 2 × 2 arrangement with types of silage and fermentation time as factors. Results: The E1 at 21 d showed the lowest gas production at 72 h (46.96 mL g-1 MS) and the lowest DMDEG (35.78%; p ? 0.05). CH4 production and total bacteria count did not show differences (p> 0.05) between types of silage, nor fermentation times. Limitations on study: The inclusion of 3% molasses with a fermentation time of 21 days showed the lowest gas production and degradation of dry matter in silage with pumpkin pulp shell and pangola grass hay. Conclusions: Silage made with pumpkin pulp shell is a viable alternative to preserve and produce feed for ruminants in the dry season; likewise, properly use potentially contaminating materials such as pumpkin pulp shell. Keywords: Digitaria decumbens, Cucurbita argyrosperma, gas production, ensilage, in vitro.

Objective: to evaluate the effect of NPK fertilization on the accumulation of dry biomass, NDVI, LAI and yield of the Cabezona pineapple (Ananas comosus (L.) Merr.) Design / Methodology / Approach: the experimental design was a randomized complete block with four replications, 14 treatments and one control. The treatments were generated with the Plan Puebla I matrix; N doses were,120, 160, 200 and 240 kg ha-1, of P were 70, 110,150 and 190 kg ha-1, and for K 150, 200, 250 and 300 kg ha-1. The N and P doses were divided into four applications, at two, five, eight, and thirteen months. P was applied in a single exhibition at the beginning of the culture cycle. Results: at the end of the cultivation cycle, all the treatments accumulated a greater quantity of biomass than the control, but no statistical difference was found between fertilization treatments. The NDVI showed no trend during the crop cycle and it was not correlated with biomass, LAI or yield. In Leaf area index (LAI) did not show statistical difference between treatments and control. In yield, a highly significant difference was observed between treatments, being treatments 5 (200-110-250) and 8 (200-150-250) where yields greater than 55 t ha-1 were obtained. Study limitations / implications. Cabezona pineapple susceptibility to mealybug attack may affect yield observations Findings / Conclusions: The Cabezona Pineapple accumulated on average 0.80 ± 0.13 g of dry biomass per day. under environmental conditions of the Huimanguillo, Tabasco, savanna. Not relationship was found between NDVI and biomass accumulation in this crop. LAI increases dramatically after flower induction treatment. Fertilization dose recomended 200-110-250, since produced a yiel of 55.5 t ha-1 of fresh fruit, and it is cheaper than others dose tested.

Abstract: The objective of the present investigation was to evaluate the agronomic performance of experimental genotypes of maize in three agro-ecological environments of the Centro de Chiapas region. During the spring summer 2016 agricultural cycle, six maize genotypes were evaluated in a randomized block design with four replications. The genotypes showed significant differences (P <0.05) for grain yield, plant height, ear length and number of rows; the interaction genotype by environment was not significant. The XT-5627 and XT-5610 genotypes showed greater stability and the first showed higher yield. The high yields were obtained in the Francisco Villa, Villaflores environment, of the Frailesca region, Chiapas. Objective: The objective of this research was to evaluate the agronomic behavior of experimental maize genotypes in three contrasting environments of the Central region of Chiapas. Design/methodology/approach: The experiments were established during the spring-summer 2016 agricultural cycle in the towns of Francisco Villa, Villaflores (730 m); San Luis, Suchiapa (600 m) and in Ocozocoautla (800 m), located in the Central region of the state of Chiapas. In the three sites, the climate is warm subhumid with rains in summer and presence of intra-festival drought during the second half of July and the first half of August.  Genetic material. The experimental genotypes were evaluated: XT-5614, XT-3402, XT-5610, XT-5612, XT-5627 and the BG7415W genotype of the Biogene company, which is used in commercial crops in the Center of Chiapas. All genotypes showed viability greater than 90%. The genotypes were distributed in the three experimental sites, which were used for seeding in a randomized complete block experimental design with four replications. The experimental unit consisted of four rows of 5 m in length each and 0.8 m apart, while the useful plot was formed by the two central rows. Variables evaluated. Days to male flowering (DFM), days to female flowering (DFF), plant height (AP), ear height (AM), ear length (LM), ear diameter (DM), rows per ear (HM) , grains per row and grain yield (REND) at 14% moisture. A combined analysis of variance (ANOVA) was carried out and the model of additive main effects and multiplicative interaction (AMMI) was used for the evaluation of the genotype x environment interaction (IGA). The analysis of variance was solved with the SAS system (SAS, 2000) while the GEA-R program was used for the AMMI model (Pacheco et al., 2015). Results: The combined analysis of variance detected differences between genotypes (G) for most of the variables except in grains per row and days to male and female flowering; Between environments (A) there were significant differences for all variables, for the environment genotype interaction (IGA), there were only significant differences for the number of rows per ear (Table 1). The values of the coefficient of variation (CV) were from 1.26 (DFF) to 10% (REND), which indicates an acceptable control (<20%) of the experimental variability. The results show a genetic variation between the evaluated genotypes, which allows selecting the most outstanding ones. The evaluation environments represent the agroecological conditions, where maize is grown in the Central region of Chiapas and because they are contrasting, they showed differential effects and this condition is necessary in the evaluation of germplasm in the process of genetic improvement (Córdoba, 1991). Limitations on study/implications: With regard to ear height, the values are acceptable as short plants favor ear rot in hot climates, when there is excess weeds before harvest. The flowering of the genotypes is considered acceptable and they were earlier (55 days) in the Suchiapa site, probably due to the high temperatures of this locality and, in addition, there was the presence of intra-festival drought, compared to the other two experimental sites. The asynchrony between male and female flowering in all genotypes was not significant. Findings/conclusions: Among the genotypes, there were significant differences for grain yield, plant height, ear height, ear length, and number of rows; the genotype-by-environment interaction was not significant. The XT 5627 and XT 5610 genotypes showed higher stability and the former showed higher grain yield. The high yields were presented in the environment of Francisco Villa, Villaflores, of the Frailesca region, Chiapas.

Objective: Analyze the contemporary scientific contributions of the Masters and Doctorate Graduate Program in Tropical Agroecosystems (PTA) taught at the Colegio de Postgraduados, Campus Veracruz, facing the current challenges of Mexican agriculture. Design/methodology/approach: A bibliographic search was carried out in SCOPUS and Web of Science, on papers (N = 92) published during 2014-2019 by PTA research-professors. A textual analysis was carried out using Nvivo Software to identify the scientific contributions, based on problematic categories suggested by FAO for Mexico. Results: Scientific contributions are more prolific in relation to the increment of agricultural productivity (66 %), to a lesser extent in sustainable practices (14.9 %), articulation of public policies (10.6%), and initiating in adaptation and mitigation of climate risks (8.5 %). Limitations of the study/implications: Findings excluded publications not indexed in SCOPUS or Web of Science or out of the analyzed period. Findings/conclusions: The PTA shows social relevance in the generation of knowledge, with scientific contributions to the current challenges of Mexican agriculture. However, they have mainly focused on increasing agricultural productivity; this does not allow the achievement of the challenges of the PTA towards research processes aimed at trans discipline. This suggests a new research role that approach disciplinary interfaces.

Objective: To conceptualize the agri-food chain and analyze its evolution during the 21st century: The case of taro. Design/methodology/approach: A systematic bibliography review was carried out in journals specialized in agri-food chains, value chains, logistics, and supply chains; these studies sustained qualitatively and based on a study case, the agri-food taro chain. Results: Currently, the agri-food chains include processes such as the supply of inputs and necessary facilities, production, transformation, distribution, and commercialization, among other services. The study of agri-food chains has effects on globalization in a more demanding macroeconomic setting. The growing industrialization of products generates added value and provides a competitive advantage to the agents that integrate the chain. However, the agri-food malanga chain presents disadvantages in its production, distribution, and storage processes, due to the disintegration of its links. Limitations of the study/implications: Scarce information exists on the malanga agri-food chain. Findings/conclusions: The agri-food chain concept has had a continuous evolution. Its structure aims to benefit each one of the chain links; compromises are generated to produce based on need. The integration and experience gained allow the strengthening and importance assessment of each link, improving revenues. Also, agri-food chains´ incorporation makes them more sensitive to climate change, nutrition, and sustainability.

Objective: Understand the productive cultural dynamics that underlies coffee agroecosystems in the Sustainable Rural Development District 005 Fortín, Veracruz, Mexico. Methodology: A survey was applied designed with open and closed questions. Data sets were subjected to analysis of variance, Tukey tests and frequency tables. Results: The coffee agroecosystems in Mexico are complex systems that underlie a particular cultural dynamic expressing a way of conceiving the world, that influences not only on their life, but also on the reproduction of certain management practices whose logic goes beyond economics. The coffee activity is carried out largely by tradition (39 %), characterized by shade-grown Coffea arabica agroecosystems (100 %), with yields lower than 5.87 t ha-1. Limitations of the study/Implications: This is a case study in a specific area of the state of Veracruz, and the results express a local reality. Findings: Producers perform up to four extra-farm economic activities to supplement their family income; paradoxically, this has served as the basis to keep carrying out the coffee activity, thus reducing their economic vulnerability and facilitating the continuity of their production methods and livelihood.

Objective: Characterize the mango value network in the State of Campeche and identify its problems. Design/methodology/approach: Based on documentary information and 40 semi-structured interviews, the structure of the value network, its key actors, and technologies were identified. Results: Researchers advise to establish high-density orchards (3 333 plants ha-1), although growers accept to increment from 69 to only 278 plants ha-1. New production technologies are required for important cultivars, such as Tommy Atkins, Manila, and creole. Their vegetative growth responds differently to local humidity, rain, and soil conditions, due to their monoembryonic or polyembryonic origin. Limitations of the study/implications:  Producers in the social sector do not keep accounting and production records. An estimate of mango yields, investment, income, and profits was obtained based on the opinion of producers from the social and business sector of Campeche. Findings/conclusions: Social sector producers of mango are willing to grow their orchards with 278 plants ha-1; it is required to evaluate the production technologies of Tommy Atkins, Manila, and creole cultivars, and to estimate the production costs. Private sector growers are choosing to substitute mango for high-density Persian lemon; they also prioritize fruit fly management and commercialization of fruits.

Objective: Analyze public policies in Mexico facing climate change in agriculture that allow the development of resilient agroecosystems. Design/methodology/approach: An analysis of research on resilience to climate change in the agricultural and rural sectors, as well as analysis of literature on public policies formulated to climate change in the agricultural sector (period 2013-2019), was realized. Results: Multiple sources of resilience for agroecosystems are present. Policies could be oriented to identify such sources and to strengthen capacities according to different scales and contexts. There is the possibility of considering factors associated with the evolution of these systems to employ strategies that are consistent and that allow coordination between political levels. Limitations of the study/Implications: This is a theoretical study restricted to the available literature published until 2019. Findings/Conclusions: Public policies require integrating the perspective of the dynamics of the complex agricultural system and the multiple sources of resilience at different scales and contexts, articulating the development of resilient agroecosystems to climate change.

Objective: Analyze the concept of resilience as an agroecosystem property to deal with the possible outcomes of climate change. Methodology: The literature was analyzed concerning concepts of resilience, vulnerability, climate change scenarios and agroecosystems resilience. Results: The resilience is an emergent property and is part of the agroecosystem trajectory, and it also is closely related with the adaptability and self-learning capacity. Limitations of the study: The strengthening of weak elements should be encouraged and promoted the agroecosystem controller feedback to increase his adaptive capacities. Conclusions: Promotion of agroecosystems resilience must start by integrating indicators in environmental, governance, risk assessment, knowledge and education dimensions, management and vulnerability reduction, and preparedness and response for disasters.