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

Objective: Calibrate two non-linear models, in three intermediate triple hybrids, by theoretically comparing the accumulation of dry matter in relation to the days after sowing. Methodology: The cuts were every 14 days, from 30 to 170 das, and were adjusted to the Logistic and Richards models. The experimental design was a randomized block, with three replications. Results: The models explained most of the total dry matter yield in corn, observed in the field at 83%. The best fit model was the logistic model in cultivar AN447 and the Richards model in cultivar A7573, both with R2=0.98. The maximum yield simulated with the Richards model was shown in AN447 with 22,616 kg DM ha-1 and the lowest in AN388 with 10,970 kg DM ha-1. Limitations/Implications: Tests of other models in the same conditions and in other environmental conditions with the models under study. Conclusion: The Logistic model allows to simulate with greater precision the yield of dry matter in corn, by using the days after planting as an independent variable.

Objective: To assess the perineal penopexy surgical technique in the preparation of teaser bulls for the bovine industry. Design: To assess the technique, three 11-month-old Swiss-Zebu bovines, with an average weight of 280 kg, were subject to a surgical procedure. The assessed parameters were time of procedure, postoperative recovery (infectious processes), and return to normal mounting. Results: This study shows a total average time ―from the beginning of the procedure until the animal can stand― of 23.7 min, plus nine days of postoperative recovery, without infectious processes. Implications: During the postoperative process, the ring might be rejected, fibrous tissue might form as a reaction to the ring’s material, and the penis might be overexposed because of the ring’s diameter. Limitations: There might be limitations resulting from the surgeon’s experience regarding the location of the sigmoid flexure. Results: Using this technique contributes to the improvement of the teaser bull preparation protocols for bovine artificial insemination programs

Objective: To develop a protocol for the aseptic in vitro establishment and multiplication of Aechmea fasciata (Lindl.) Baker. Design/Methodology/Approach: Different concentrations of NaClO (2, 3, 4, and 5%) were assessed for the aseptic establishment of A. fasciata. During the shoot induction stage, the three following treatments were tested: T1 = 6-benzyladenine + naphthalene-1-acetic acid (BA + ANA; 5 + 2 mg L-1); T2 = zeatin + 2,4-dichlorophenoxyacetic acid (Zea + 2,4-D; 5 + 2 mg L-1); and T3 = control with no plant growth regulators. During the shoot multiplication stage, three more treatments were assessed: T1 = Zea + 2,4-D (2.5 + 1 mg L-1); T2 = Zea + 2,4-D (5 + 2 mg L-1); and T3 = Zea + 2,4-D + gibberellic acid (AG3) (2.5 + 1 + 3.5 mg L-1). To assess the number of cellular events, different nitrate concentrations were tested in the medium (18.8, 39.4, and 60 mM NO3-). Finally, during the shoot regeneration stage, nine treatments derived from the combination of three concentrations of kinetin (KIN: 0, 0.1, and 0.5 mg L-1) and of indole-3-acetic acid (AIA: 0, 0.3, and 0.4) were assessed. Completely randomized designs were used in each stage. Duncan’s test (p ≤ 0.05) was used to compare the means during the shoot induction and multiplication stages. A regression analysis was carried out to study the aseptic establishment and a non-parametric test (Kruskal-Wallis) was made to assess the “amount of microshoots during regeneration” variable. Results: A. fasciata aseptic explants with 4% NaClO were established. Shoot induction was most effective with the BA + ANA (5 + 2 mg L-1) treatment. The highest callus production was reported with the Zea + 2,4-D (5 + 2 mg L-1) treatment. The largest number of microshoots was obtained with high nitrate doses. Meanwhile, the most successful regeneration was achieved with the 0.1 mg KIN L-1 and 0.4 mg AIA L-1 treatment. Study Limitations/Implications: The application of Zea and 2,4-D during multiplication induced callus formation. Findings/Conclusions: Apical bud explants in an MS medium with BA and ANA present organogenesis. The use of Zea and 2,4-D forms calluses in the already established in vitro shoots, which regenerate with the use of KIN and AIA. Better microshoot coloring and development were achieved with MS salts, which have a medium nitrate content.

Objective: Evaluate the tolerance of native maize populations of Tamaulipas to foliar damage by S. frugiperda. Design/methodology/approach: In Güémez, Tamaulipas, in the two agricultural cycles of 2019, the foliar damage of S. frugiperda and the decrease in grain yield were evaluated in 10 populations of native corn of Tamaulipas.                            Results: With the application of a synthetic insecticide (emamectin benzoate), minimal foliar damage by S. frugiperda was observed in the autumn winter agricultural cycle. While in the spring-summer cycle, greater foliar damage was observed, which remained at lower levels than the rest of the S. frugiperda management strategies. Limitations on study/implications: S. frugiperda it is an important pest of maize, its control is mainly carried out with synthetic insecticides, which causes environmental and human health risks, the use of tolerant cultivars is a strategy that reduces these risks. Findings/conclusions: In the spring-summer cycle, there was greater foliar damage, as a consequence of a higher environmental temperature compared to the autumn-winter cycle; the TML2S3 and VHA maize populations were tolerant to S. frugiperda foliar damage in both agricultural cycles, being considered as base germplasm to start an improvement program for this characteristic.

Objective: Evaluate the performance of two soybean cultivars submitted to water deficit in two sowing seasons (July 10, 2019, and October 27, 2020), in Tocantinense Savannah, Brazil. Methodology: The experiments were carried out in a greenhouse, in pots. The experimental design used in each experiment was completely randomized in a 4 x 2 factorial scheme with four replications, represented by four irrigation management systems (water deficit in the flowering, grain filling and maturation stages, and without water deficit) and two cultivars (TMG132RR™ and TMG1288RR™). The means were grouped by the Scott-Knott test at 5% significance. The characteristics evaluated were: number of seeds per plant, mass of one hundred seeds in grams, number of pods per plant, plant height and grain yield per hectare (GY) in kilograms. Results: In the two seasons, the water deficit during grain filling affected the number of pods and seeds per plant, the 100 seeds mass, and the grain yield of both cultivars. Implications: The water availability and sowing seasons are environmental factors with the greatest impact on cropping. Therefore, understanding how cultivars behave in adverse environmental situations is of great importance to management programs. Conclusions: The cultivar TMG132RR™ was less sensitive to water deficit, whereas the cultivar TMG1288RR™ was more productive under adequate conditions of temperature and water availability.

Objective. To validate a simulation model which enables the estimation of wheat (Triticum aestivum L.) production, based on climatic variables in the lower Mayo River basin in Sonora, Mexico. Design/methodology/ approach. The Soil and Water Assessment Tool (SWAT) Crop Yield simulation model was used to estimate productive wheat yields. The model was fed with climatic data for the 1979-2014 period, provided by the National Centers for Environmental Prediction. Subsequently, the results were validated using the Nash-Sutcliffe, PBIAS, and R2 statistics. The predictive capacity of the model was validated in four of the six Hydrological Response Units with agricultural land in the study area: 26, 27, 28, and 31. Study limitations/implications. The model does not include adaptation measures and future production scenarios based on climate data estimation must be developed. Findings/conclusions. The influence of climate change on wheat production has been confirmed; the predictive model used is an important tool that can be adjusted and adapted to other regions and production systems.  

Objective: To evaluate the effect of different doses of selenium on seminal quality and fertility in rams. Design/methodology/approach: Nine rams were evaluated. Selenium was offered subcutaneously at two months of age of the rams each month. Treatments were T1= no selenium, T2= 0.1 mg/kg selenium, and T3= 0.3 mg/kg selenium. Seminal evaluation was performed at seven months of age on the rams using an electroejaculator, and a total of 180 ejaculates were analyzed. The rams with the best seminal quality (one per treatment) were submitted to mating. The variables evaluated were: volume (Vol), mass motility (MM), progressive motility (PM), sperm concentration per mL and per ejaculate, percentage of complete acrosome, percentage of live sperm, percentage of normal sperm and percentage of fertility. Variables with normal distribution were evaluated with an analysis of variance (ANOVA; Tukey, 0.05) and the percentages were raised to arcsine to perform the corresponding ANOVA. Fertility was analyzed with a Chi-square test. Results: Seminal quality and fertility percentage were not different (P >0.05). Ejaculate volume showed differences (P <0.05). Limitations/implications: The study with a larger number of rams and a previous practice in field work for the evaluation of semen parameters is necessary for a better estimation of semen quality and fertility and to verify the results. Findings/conclusions: Selenium did not improve seminal quality and fertility in rams.  

ABSTRACT Objective: To quantify the percentage of pregnant cows slaughtered in the municipal abattoir of Pijijiapan, Chiapas, and the gestation state of the products. Approach: A high number of pregnant cows are slaughtered due to several factors, such as the low number of pregnancy tests performed and misdiagnoses. The dry season is another factor that reduces forage capacity. It enforces ranchers to get rid of animals, including pregnant cows, reducing the cattle herd population. However, it might also be considered an animal welfare issue. Methodology:  It was registered the total number of bovines slaughtered in four months. The number of females sacrificed was quantified and recorded if they were pregnant or not and the gestational status of the products.  Results: There were 428 bovines slaughtered; 399 were females (93.22%), and 29 were males (6.78%). Of the females, 211 (53%) were pregnant. It was found that 39.81% were in the first third of gestation, 27.48% in the second third of pregnancy, and 32.22% in the last third.  Limitations: It is necessary to extend the study period and not just in this municipality but to understand better the situation in other abattoirs in Chiapas.

Objective: To detect productive factors that explain the total value of agricultural production (agricultural GDP) and carry out a descriptive analysis. Methodology: A multiple linear regression adjustment and a descriptive analysis of the variables for which information is available were carried out. Results: Five variables were found to have a significant association with agricultural GDP. In the last 20 years, the agricultural sector has experienced exponential economic growth with an annual growth rate (TCMA) of 7.7%, about 60% of the total value of production is provided by only 7 states, agricultural exports increased from 2015 due to demand from the United States for Mexican fruits and vegetables. Implications: Information on the state of agriculture in Mexico makes it possible to understand trends and take actions to increase the growth of agricultural GDP. Many variables do not have updated information, which limits the analysis. Conclusions: The sown agricultural area has decreased and the productive factors analyzed maintain a positive average annual growth rate, which indicates a process of transition from extensive crops, such as grains and cereals, to intensively exploited crops, such as fruits and vegetables. It is necessary to invest in the generation of agricultural data.

Objective: To analyze the characteristics and socio-productive problems of the mezcal women of Oaxaca, Mexico. Design/methodology/approach: The information was obtained in the field through a semi-structured interview with 20 women mezcal producers. Results: The women are in mid-adulthood, have basic education, and with extensive experience in the activity. It was identified that 35% of them make decisions entirely about the business and the home. The price of mezcal (35%) and the shortage of maguey (30%) are the main problems perceived in the activity. Women face social limitations such as work overload at home, no access to productive support, and low participation in rural organizations. Limitations of the study/implications: It is convenient to carry out a greater number of studies on mezcal women in Oaxaca. Findings/conclusions: The collective work and organization can be an alternative that improves the benefits and quality of life of the families of mezcal women. There is a need to design public policies with a gender perspective and appropriate to the needs of the women who participate in the activity.