Colegio De Postgraduados Research Articles

Characterization of weed flora in a cassava crop in Tabasco

Objective: To evaluate the effect of the incorporation of Crotalaria juncea L. as green manure on the weed community in a cassava crop in Tabasco. Design/methodology/approach: The study was carried out in the Experimental Field of Colegio de Postgraduados, Campus Tabasco (18º01' N and 93º03' W). The samplings were made on four dates: 1) at the planting of crotalaria (12/03/2018); 2) at flowering (31/01/2019); 3) 20 days after incorporation (22/02/2019); 4) at cassava harvest (25/04/2019), using metal squares 50 x 50 cm. Two planting densities, 50 and 80 cm (16,600 and 10,375 plants ha-1), two doses of NPK fertilization (160-40-80 and 00-40-80+GM), and a control were tested. The name of the species, number of individuals and coverage (percentage) were recorded to calculate the richness (S), Shannon diversity (H') and uniformity (E) indices, and the importance value index (IVI). Results: The weed community consisted of 32 species, 28 genera and 16 families, of which the best represented are: Convolvulaceae, Asteraceae, Cyperaceae and Poaceae. The most frequently recorded species are Lindernia crustacea, Ludwigia octovalvis, and Ageratum houstonianum. The diversity indices reflected a poor community, especially with GM treatments; diversity ranged from low to medium and uniformity from medium to high. The importance of the families was more related to the environmental conditions than to the treatments; Cyperaceae were more important in the rainy season and Asteraceae in the dry season. L. crustacea appeared throughout the cycle. Limitations/implications: It is advisable to extend the investigation period. Findings/conclusions: The weed flora consisted of 32 species; the Convolvulaceae family was the most diverse and L. crustacea was the most recorded species during the cycle. The diversity indices reflected a poor community. The importance of the families was related to environmental conditions, where Cyperaceae stood out in the rainy season and Asteraceae in the dry season

ASSESSMENT OF THE GENETIC DIVERSITY OF NEW SUGARCANE HYBRIDS USING PRINCIPAL COMPONENT AND CLUSTER ANALYSES

With a cultivated area of approximately 800 thousand hectares distributed in 15 states, sugarcane (Saccharum spp.) is one of the main crops in Mexico. Despite its socioeconomic importance, the genetic base of this crop has been reduced in recent decades, making the production system vulnerable to both biotic and abiotic stresses. For this reason, the Colegio de Postgraduados Campus Córdoba initiated a varietal selection program in 2009. In this study, morphological and agronomic attributes of 20 advanced hybrids were analyzed during the 2020-2021 and 2021-2022 growing seasons to determine genetic variability based on principal component analysis (PCA) and cluster analysis. Commercial cultivars widely planted in the area of influence of the Córdoba Campus (CP 72-2086, Mex 79-431, Mex 69-290 and Mex 05-204) were used as reference samples. In terms of agronomic indicators, most of the new hybrids showed higher averages than the commercial control cultivars. The hybrids COLPOSCCMex 09-50 and COLPOSCCMex 09-66 showed better germination capacity. The average height of the tallest milling stems was presented by the hybrids COLPOSCCMex 09-341 (318.1 cm) and COLPOSCCMex 09-93 (311.85 cm). The hybrid COLPOSCCMex 09-289 showed outstanding values for five variables: diameter (36.43 mm), °Brix (21.89 %), stem height (149.33 cm), leaf width (5.36 cm) and number of leaves (11.15). Morphological characterization was carried out according to 54 descriptors, combining categorical and continuous traits that were easy to observe, with a high degree of differentiation and low environmental influence. Principal component and cluster analyses showed the distribution of hybrids into five groups. These results show promising sugarcane lines with high yields, which can contribute to genetic diversity in agroecological zones where they can be adapted.

FERTIGATION DISTRIBUTION WITH LOW PRESSURE MULTIGATE IRRIGATION SYSTEMS IN A SUGARCANE AGROECOSYSTEM

In the state of Veracruz, Mexico, low sugarcane yields are reported despite the high use of inputs. This results in economic losses and environmental pollution. A fertigation system designed at the Colegio de Postgraduados (COLPOS) Campus Veracruz was established to determine the uniformity and stability of fertilizer distribution in the sugarcane crop. This study was carried out in a sugarcane plot with a farmer participant. Three levels of valve openings at the injector inlet (1/3, 2/3, and 3/3) were tested to determine the homogeneity of fertigation at the outlet of the gates and the stability of the system over time. Samples of water-fertilizer mixture were taken at the outlet of the gates. They were analyzed in the laboratory with a UV-visible spectrophotometer at 202 nm for nitrogen. It was found that the 1/3 and 3/3 valve position openings caused instability in the system. For the 2/3 opening with p = 0.359, no statistical difference (α= 0.05) was found during the time of emptying the container of the water-fertilizer mixture. Therefore, the fertigation system proved to be stable with a valve opening close to 2/3. Using the valve openings, the flow rate of water-fertilizer entering the system is uniformly mixed at the outlets of the multi-gate pipeline that pours into the crop furrows (p = 0.474 and α = 0.05). It can be concluded that in fertilization using a low-pressure irrigation system, nitrogen fertilizer is uniformly distributed when a Venturi type injector is used in a sugarcane agroecosystem with a valve opening close to 2/3.

First Report of Fusarium citri Causing Postharvest Fruit Rot of Chayote in Mexico.

In November 2018, symptoms of brown rot were observed on chayote (Sechium edule) var. nigrum spinosum with a 20% disease incidence of 120 harvested fruits in the National Germplasm Bank of Sechium edule, located in the Centro Regional Universitario Oriente (CRUO) from the Chapingo Autonomous University (Huatusco, Veracruz, Mexico). For fungal isolation, pieces from symptomatic fruits were surface disinfected by immersion in a 1.5% NaClO solution for 2 min, rinsed in sterile distilled water, placed in Petri plates containing potato dextrose agar (PDA) amended with kanamycin sulfate, and incubated at 25ºC. Fusarium-like colonies were consistently isolated on PDA and five monoconidial isolates were obtained. A representative isolate was selected for morphological characterization, phylogenetic analysis, and pathogenicity tests. On PDA, colonies exhibited white and fluffy aerial mycelia, with diffused pale brown pigment in the center at 7 days of incubation at 25℃ in darkness. Macroconidia (n= 100) were hyaline, falcate, with 4 to 5 septa, measuring 23.9 to 31.9 × 2.9 to 4.2 μm, and foot-shaped basal cells. Microconidia and chlamydospores were absent. Morphological features were consistent with the description of the Fusarium incarnatum-equiseti species complex (Xia et al. 2019). The isolate was deposited as FUS2 in the Culture Collection of Phytopathogenic Fungi of the Laboratory of Plant Pathology at the Colegio de Postgraduados. For molecular identification, genomic DNA was extracted, and the internal transcribed spacer (ITS) region, partial sequences of translation elongation factor 1-alpha (EF1-α), and the second-largest subunit of RNA polymerase II (rpb2) genes were amplified, and sequenced with the primer sets ITS5/ITS4 (White et al. 1990), EF1-728F/EF1-986R (Carbone and Kohn 1999), and RBP2-5F/RPB2-7R (Liu et al. 1999), respectively. DNA sequences were edited in BioEdit 7.2 and compared with those in the NCBI nucleotide database. Alignments were implemented in MEGA X using reference sequences from Fusarium spp. A phylogenetic tree, including published ITS, EF1-α, and rpb2 sequence data, was constructed for the Fusarium incarnatum-equiseti species complex (FIESC) based on Maximum Likelihood. The sequences were deposited in GenBank (accession nos. ON878083, ON890421, and ON890420). The phylogenetic analysis grouped the isolate FUS2 within the F. citri clade. Pathogenicity of the fungus was verified on 10 healthy chayote fruits var. nigrum spinosum previously disinfested by immersion in a 1% NaClO solution for 3 min and washed in sterile water. A total of 5 mL of a conidial suspension (1 × 106 spores/ml) was sprayed on each whole fruit. Ten control fruit were sprayed with sterile distilled water. The fruits were kept in a moist plastic chamber at 25°C and 12 h light/dark for 30 days. All inoculated fruits developed water-soaked brown lesions (3 to 5 cm in diameter) covered with white mycelium at 15 days after inoculation, whereas no symptoms were observed on the control fruits. The fungus was consistently re-isolated only from the diseased fruits and found to be morphologically identical to the isolate used for inoculation, fulfilling Koch´s postulates. Fusarium citri has been associated with Capsicum sp. and mandarin orange in China, Triticum sp. in Iran, alfalfa in Denmark, and lettuce in the Czech Republic and Italy (Farr and Rossman 2022). To our knowledge, this is the first report of F. citri causing postharvest fruit rot of chayote in Mexico and worldwide.

Bibliometric Analysis of Forestry Research in Mexico Published by Mexican Journals

There is scarce research assessing the productivity of scientific articles on forestry topics. The objective of this study was to analyze the scientific production on forestry topics that originated in Mexico and were published in Mexican journals from 1996 to 2019 and to identify the causes that determine the impact factor of such publications and the space-time evolution of forestry research in Mexico. In addition, to analyze whether researchers tend to publish in journals published by their affiliation institutions. The study considered 2384 scientific articles from seven journals belonging to category VI of Biotechnology and Agricultural Sciences listed in the Journals Classification System by the National Council of Science and Technology that publishes forestry topics. Bibliometric indicators were generated through text mining and analysis of co-authorship networks. It was found that forestry research in Mexico from 1996 to 2019 presented exponential growth in the number of publications. Forestry scientific production was concentrated in the center of the country. It was dominated by researchers from three of 122 institutions: Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias (13.88%), Colegio de Postgraduados (12.50%), and Universidad Autonoma Chapingo (10.44%). The journals with the highest number of publications were: Revista Mexicana de Ciencias Forestales (26.51%), Revista Chapingo Serie Ciencias Forestales y del Ambiente (20.34%), and Madera y Bosques (18.88%). Results show that forestry researchers in Mexico published mostly in journals edited by their affiliation institutions, which restricts constructive criticism of peer review and increases academic endogamy. Also showed the need to generate more forestry research for the southeast of the country on topics such as climate change, carbon capture, forest biometry, and remote perception, which are relevant aspects when we consider that no published research evaluated the development of the forestry sector in Mexico.

Ants associated to prickly pear cactus crop in Texcoco, State of Mexico

In Mexico, center of domestication of prickly pear cactus species (also called “nopales”) few studies exist on insects associated with this crop. The studies are scantier on ants, since the majority are not considered to be pest. For this motive, the population dynamics of the ants was studied in experimental prickly pear crop in the installation of Colegio de Postgraduados, Mexico. The sample was fortnightly performed from February 2013 to March 2014. Ants were gathered with pitfall traps and arboreal traps, all of them with three baits and others without bait. Also recorded raiding, the nests in crop and inside to the cladodes. We collected a total of 10,953 individuals (74 % on ground and 26% on prickly pear cladodes), and seven species were determined: Hypoponera opacior (Forel), Neivamyrmex nigrescens (Cresson), Pogonomyrmex barbatus (Smith), Linepithema humile (Mayr), Camponotus atriceps (Smith), Pheidole obtusospinosa Forel and Monomorium minimum (Buckley). The last four were more abundant and frequent. We discuss the presence and nesting of ants in crop and their association with other insects of prickly pear crop.

Vegetative propagation of bird’s-foot trefoil (Lotus corniculatus L.) using different rooting agents

Objective: To evaluate the growth dynamics based on the dry matter production of Lotus corniculatus L. variety 202700 and its morphological composition.
 Design/Methodology/Approach: The study was carried out in the glass greenhouses of the Colegio de Postgraduados in Montecillo, Texcoco, Edo. Mexico, from December 2020 to May 2021. The effect of indole butyric acid (IBA) growth promoter in solid presentation Radix 1500 and liquid Radix T 3000 (S+ESolid and S+ELiquid) and a control (Substrate) was evaluated., a completely randomized design with three replicates was used, each with twenty pots as replicates. 1300 pots were planted, of which 20 of each treatment were taken monthly (30, 60, 90, 120 and 150 days) for subsequent data recording.
 Results: S+ESolid was the one that presented the highest values ​​followed by S+ELiquid and Witness (S) respectively.
 Study Limitations/Implications: Destructive sampling of less than 30 days or greater than 150 days was not considered.
 Findings/Conclusions: The plants with the application of 1500 ppm of IBA registered the greatest response in terms of variables: number of leaves, number of stems, leaves (g), stems (g), roots (g), root height (cm), root volume (cm3), greenness index, leaf area (cm2 /g) and plant height (cm), with respect to the rest of the treatments.

My interest for agriculture and COVID-19 emotions as graduate student

<p>My name is Agustin Gonzalez Cruces, I am an agronomist, specialized in Agricultural Parasitology, and I graduated from the Universidad Autónoma Chapingo. My grandfather is a kind, sensitive, old-fashioned man with a firm hand. He is an example of perseverance and determination in the farming vocation. He pointed me towards my decision to study agronomy. In this teenage phase of my life, with the rebelliousness that characterizes that moment in life, he told me: <em>‘If you stay to study in Chapingo, I’ll leave you my lands and tech you the secrets of agriculture’</em>. I remember that as being my initial motivation to enter that prestigious university. Love for the countryside was not an unknown feeling for me, since he always took us to work his fields, sometimes for weeding, irrigating, or other times for harvesting, with his typical saying: ‘<em>To know how to order you have to know how to get things done’. </em>I write “he took us” because my cousin, Ángel Campos, who happens to study the same career as I in the Universidad Agraria Antonio Narro, came along. Due to this, I dare to say it was my grandfather who turned us into men with a peculiar love for the countryside. After graduating I began setting up orchards for sale and giving technical consultation to farmers, including my grandfather, Mr. Bernardino Cruces, who has honestly been the most reluctant and stubborn farmer I have met, with his saying: <em>‘One thing is theory and another, very different thing is practice’</em>, referring to his experience as a farmer and defending his empirical knowledge from being undermined. My grandfather was one of the first farmers to establish asparagus crops in the area of Atenco, State of Mexico, which is why I decided to specialize in that very kind and gentle plant. Whenever I’m immerse in its luscious foliage, it makes me think. I think about the way we plant, with all its stages and the goal of farming, which is to contribute to feeding society. I reflect upon the teachings of my grandfather, who has been my only fatherly figure. The COVID-19 pandemic meant a drastic change in my daily routine. When the infections began I became alert and got scared. I tried to tell my family what a virus was in the simplest way possible, because they did not understand the nature of the pathogen. I was about to finish my first term of my Master’s Degree in Phytopathology in the Colegio de Postgraduados, Campus Montecillo. I was restless, motivated and excited to take a lesson and learn from the best phytopathologists. Now, with video lessons, although the motivation to learn is still there, it isn’t the same. My way of learning is visual and practical, and I think video lessons do not fulfill my expectations. When I took a lesson on Agricultural Epidemiology with Dr. Gustavo Mora Aguilera, my vision of the pandemic changed. In his course, which was in-person, by the way, he told us about working on the psychology of fear, he encouraged us to face the pandemic with science, and would not let us freeze out of fear of getting infected, reaffirming the idea that the knowledge of the pathogen and its spread was the key to its prevention and management. That course broadened my perspective as a plant pathologist towards SARS-CoV-2. I understood that by taking the measurements to prevent contagion we could carry out certain activities to bring us closer to normality. I have not allowed the ongoing situation to interfere too much with my personal and emotional lives. I try to go about my daily routines, I haven’t stopped doing research or exercising, let alone going to the fields, always taking the adequate preventive measures. I trust that scientific progress with make the pandemic situation better. I have no fear of getting infected, although I do look after myself as much as possible so I don’t infect my mother or grandparents. History has marked us with similar pandemic situations, with unknown pathogens, and it is the knowledge of these that has helped us pull forward as a species. We know that a system in entropy always tends towards balance. My hope lies with producers, farmers and cattle breeders; that primary sector that fills me with pride and motivation, since they carry the most important responsibility on their shoulders: human nutrition.</p>

Hedonic perception and preference analysis of double cream cheeses formulated with raw and pasteurized milk

Objective: To compare the characteristics of double cream cheeses made with raw and pasteurized milk per liking and preference level. Design/Methodology/Approach: Cheeses from three brands were evaluated: Santa Teresa, Montero, and Colegio de Postgraduados (CP). The first two cheeses were formulated with raw milk, while the CP cheese was formulated with pasteurized milk inoculated with lactic cultures. The hedonic perception study was carried out in monadic series with 19 volunteers who blind tasted the three types of cheese. The evaluation attributes were: appearance, taste, aroma, and general acceptability on a 9-point scale; and saltiness, acidity, and creaminess on a 3-point scale (JAR). Preferences were evaluated by rank and multiple comparison tests. Results: No differences were found in the aroma, taste, and texture liking level of the cheeses (p>0.05); nevertheless, there were differences in the appearance and general acceptance (p˂0.05). The general acceptance of the CP cheese was significantly lower than that of the two raw milk cheeses (p˂0.05). The penalty analysis showed that low acidity and low creaminess attributes are related to a low general acceptance (p˂0.05). Limitations/Implications: The study has enough evaluations for statistical tests. Findings/Conclusions: Raw milk cheeses obtained the highest marks in all attributes. Determining if there are other sensory attributes —in addition to those that were the subject of this study— will help to explain the greater preference and global acceptance of raw milk cheeses.

Sheep reproductive management

Objective: To describe some reproductive management programs that allow increasing the productive efficiency of ewes. Design/methodology/approach: Description of the main hormones and their application in sheep reproductive management protocols. The subjects are reviewed based on academic references as well as on their use in sheep reproductive protocols at the Sheep and Goat Reproduction Laboratory of the Colegio de Postgraduados, Mexico. Results: Hormones, socio-sexual strategies, reproductive protocols and techniques are tools that improve the reproductive efficiency of ewes during the reproductive season and seasonal anestrus. Study limitations/implications: The basic techniques of reproductive management and protocols in sheep are mostly available, however, they still have room for improvement, therefore, multiple efforts involving all participants, such as the primary sector, public and private institutions, are required. Findings/conclusions: Reproductive management is an important pillar for animal production; thus its implementation is fundamental to improve the reproductive and productive efficiency of a herd

Natural Enemies Associated with Brevipalpus sp. (Acari: Tenuipalpidae), Vector of Citrus Leprosis

Natural Enemies Associated with <i>Brevipalpus</i> sp. (Acari: Tenuipalpidae), Vector of Citrus Leprosis

Post-harvest quality and quantification of betalains, phenolic compounds and antioxidant activity in fruits of three cultivars of prickly pear (Opuntia ficus-indica L. Mill)

Postharvest quality, quantification of betalains, phenolic compounds, and antioxidant activity of peel, pulp, and juice of fruits of three prickly pears (Opuntia ficus-indica L. Mill.) cultivars of Colegio de Postgraduados in México, were measured. The red and orange cultivars showed outstanding features of postharvest quality (size, texture, TSS and pulp and juice content) highest content of betalains and phenolic compounds. Therefore, highest antioxidant activity. In general, the highest content of bioactive compounds was detected in the peel, besides the content in pulp and juice did not show statistically significant differences. Phenolic content is very high in comparison with other fruits. Antioxidant activity was measured by three assays:FRAP, ABTS, and DPPH. Three cultivars showed a high correlation between antioxidant activity and phenolic compounds. The methodologies used in this work are a very useful tool for the quantification of bioactive compounds in O. ficus-indica fruit tissues.

Post-harvest quality and quantification of betalains, phenolic compounds and antioxidant activity in fruits of three cultivars of prickly pear (Opuntia ficus-indica L. Mill)

Postharvest quality, quantification of betalains, phenolic compounds, and antioxidant activity of peel, pulp, and juice of fruits of three prickly pears (Opuntia ficus-indica L. Mill.) cultivars of Colegio de Postgraduados in México, were measured. The red and orange cultivars showed outstanding features of postharvest quality (size, texture, TSS and pulp and juice content) highest content of betalains and phenolic compounds. Therefore, highest antioxidant activity. In general, the highest content of bioactive compounds was detected in the peel, besides the content in pulp and juice did not show statistically significant differences. Phenolic content is very high in comparison with other fruits. Antioxidant activity was measured by three assays:FRAP, ABTS, and DPPH. Three cultivars showed a high correlation between antioxidant activity and phenolic compounds. The methodologies used in this work are a very useful tool for the quantification of bioactive compounds in O. ficus-indica fruit tissues.

Descriptions of Trichodorus lownsberyi sp. n., Nanidorus minor (Colbran, 1956) Siddiqi, 1974 (Nematoda: Trichodoridae) and Longidorus quercus sp. n. (Nematoda: Longidoridae) from Mexico

Summary A new species of stubby root nematode, Trichodorus lownsberyi sp. n., collected from soil around Buxus sempervirens at Montecillo Campus, Colegio de Postgraduados, Mexico, is described and illustrated. Trichodorus lownsberyi sp. n. is characterised by the abundant males with a characteristic spicule shape, the narrower part about mid-blade having visible bristles in most specimens, and the presence and position of the three ventromedian cervical papillae, which are all anterior to the secretory-excretory pore. Females possess a rhomboid-shaped vagina and oval to rounded triangular vaginal sclerotised pieces with a pore-like vulva. The phylogenetic relationships of T. lownsberyi sp. n. with related species were constructed using the ITS2 rRNA and the D2-D3 expansion segments of 28S rRNA gene sequences. Trichodorus lownsberyi sp. n. was a sister species to T. viruliferus in the phylogenetic trees. A Mexican population of Nanidorus minor from a peach orchard is also described and illustrated. The new needle nematode, Longidorus quercus sp. n., was recovered from soil around roots of oak, Quercus crassipes, from Cerro Jusda ‘El Diablo’ in Mexico State. Longidorus quercus sp. n. females are characterised by the C-shaped posterior end of the body after fixation, L = 4.9 (3.9-5.6) mm, a = 71 (60.8-93.2), lip region rounded, sometimes slightly flattened, marked by depression, odontostylet 170 (144-206) μm long, hemispherical to bluntly conoid tail and no males. The new species was characterised using the D2-D3 of 28S rRNA and COI gene sequences. The phylogenetic relationships of L. quercus sp. n. with other Longidorus species were reconstructed using the D2-D3 of 28S rRNA gene sequences.

Effects of water restriction on carbohydrates concentration, starch granules size and amylolytic activity in seeds of Phaseolus vulgaris L. and P. acutifolius A. Gray

Background: Seed mass is a key component of adaptation in plants that are strongly affected by development and maturity, and, at the same time, all is modulated by the environment of cultivation.&#x0D; Hypotheses: The response to water deficit in seeds of P. vulgaris L. and P. acutifolius A. Gray is species-dependent and affects their biochemical and morphological characteristics.&#x0D; Studied species: The studied cultivars were Rosa Bufa ( P. vulgaris ) and cv. 10017 ( P . acutifolius ). Seeds were obtained from plants grown at 100 % and 25 % soil field capacity during their pod development. &#x0D; Study site and dates: The experiments were performed during May and August 2018 in a greenhouse at the Colegio de Postgraduados, Texcoco, State of Mexico (altitude 2,353 m).&#x0D; Methods: The biochemical and morphological characteristics and the grain size of starch in seeds cotyledons were assessed.&#x0D; Results: Water restriction had no significant effects on the seed thickness, width, or mass only length decreased in P. acutifolius . In both species, the axis size of the starch granules decreased due to the stress, glucose concentration increased, sucrose and starch were not altered. Water imbibition increased six times in P. vulgaris seeds with no effect on the germination. The α-amylase activity was 25 - 35 % lower in both species due to the water restriction, particularly in P. acutifolius the activity was two-fold higher than in P. vulgaris .&#x0D; Conclusions: Comparing the carbohydrate concentration in germinating seeds of common and Tepary beans gave insights on the nutrient reserves mobilization during seed maturation and germination.

Advances in the selection program of sugarcane (Saccharum spp.) varieties in the Colegio de Postgraduados

Objective: To describe the advances in the sugarcane variety selection program that is carried out by the Campus Córdoba of the College of Postgraduates in Agricultural Sciences located in Amatlán de los Reyes, Veracruz, Mexico. Design/methodology/approach: For the selection of sugarcane varieties, the methodology developed by the Institute for the Improvement of Sugar Production (IMPA) was used, and for the varietal description, the protocol of the International Union for the Protection of New Varieties of Plants (UPOV) was implemented. Results: In 2009, the Campus Córdoba started the varietal selection program with more than 6 thousand hybrids from 40 crosses, of which 4422 materials were selected after showing resistance to the sugarcane mosaic virus. From the 4422 materials of the seedling phase, 352 clones were selected and evaluated in the Furrow Phase, selecting 57 varieties for the Plot Phase. Of these 57 varieties, 36 were selected in the Adaptability Test Phase, and 27 in the following Agroindustrial Evaluation Phase. Of these last 27 varieties, estimated yields are greater than 100 t ha-1, with good quality of juices and agronomic characteristics. Study limitations/implications: The program has faced climate and budget challenges, delaying progress. Currently, the Covid-19 pandemic has drastically affected our research. Findings/conclusions: This breeding and variety selection program started with 6,000 crosses, of which to date there are 27 in advanced stages of selection, with the possibility of adaptation and good yields for the area of influence of the Campus Córdoba.

The Postgraduate Course in Tropical Agroecosystems: Facing the Challenges for Mexican Agriculture in the 21st Century

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.

Evaluación de la calidad física y fisiológica de semilla de maíz nativo

La calidad de las semillas es un elemento de importancia para que los productores y empresas semilleras tomen decisiones, como el tipo de semilla y superficie a sembrar, por esta razón las pruebas de calidad física y fisiológica son necesarias para estimar su eficacia. Adicionalmente el deterioro de la semilla de maíz (Zea mays L.) es causa de baja calidad física, fisiológica y sanitaria. En este estudio, realizado en el Laboratorio de Análisis de Semillas del Colegio de Postgraduados, Montecillo Estado de México en el año 2016, se evaluó el daño causado por impacto, envejecimiento acelerado y estrés de frio sobre la calidad física y fisiológica de semillas de maíz. Tomando en cuenta las variables; longitud de plántula, longitud de coleoptilo, longitud de raíz y peso de materia seca. Las diferentes pruebas mostraron que el genotipo tres correspondiente al ciclo 2015 fue de mejor vigor y calidad de semilla, en particular la prueba de frío indicó que la variedad nativa de la región es apta para zonas frías.

ADAPTACIÓN DE MAÍZ TUXPEÑO A VALLES ALTOS DE MÉXICO MEDIANTE SELECCIÓN MASAL

México cuenta con amplia variabilidad genética de maíz (Zea mays L.) que aún no ha sido aprovechada en su totalidad. Los programas de mejoramiento genético en Valles Altos han utilizado principalmente variedades de las razas locales Cónico y Chalqueño, con poco o nulo uso de materiales exóticos de otras regiones. En este estudio se evaluó el rendimiento de grano de cuatro poblaciones de maíz Tuxpeño como criterio de adaptación a valles altos. Las poblaciones se evaluaron en su versión Ciclo 1 (desadaptado) y Ciclo 7 (adaptado), junto con los híbridos H-S2, Promesa y San José como testigos. La evaluación se realizó en los campos experimentales del Colegio de Postgraduados y del Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, ubicados en Texcoco, Estado de México. En ambas localidades se utilizaron diseños experimentales de bloques completos al azar con tres repeticiones. Se registró la floración masculina y femenina, altura de planta y de mazorca, longitud y diámetro de mazorca, número de hileras y granos por hilera, y rendimiento de grano. Los resultados mostraron cambios significativos en el rendimiento de grano y sus componentes en el ciclo avanzado de selección C7 (5.5 a 7.9 t ha-1) en comparación al C1 (1.5 a 2.2 t ha-1). Los componentes de rendimiento con cambios significativos favorables fueron longitud y diámetro de mazorca, número de hileras y granos por hilera. Las poblaciones C7 superaron en rendimiento hasta en cinco veces a las del ciclo inicial; sin embargo, no igualaron el rendimiento de 11.4 t ha-1 de los híbridos testigo. Las poblaciones de maíz Tuxpeño C7 pueden considerarse como variedades exóticas tropicales adaptadas a Valles Altos, pues mostraron rendimientos de 5 a 7 t ha-1; además, aportan variación genética nueva que puede utilizarse en el mejoramiento del maíz local o de manera per se como variedades nuevas.

Estructura social y resiliencia en instituciones mexicanas de investigación agropecuaria

&lt;div class="page" title="Page 1"&gt;&lt;div class="layoutArea"&gt;&lt;div class="column"&gt;&lt;div class="page" title="Page 1"&gt;&lt;div class="layoutArea"&gt;&lt;div class="column"&gt;&lt;p&gt;&lt;span&gt;La resiliencia social es un proceso multiorganizacional que involucra capacidades de innovación, soporte, protección y recuperación en comunidades e instituciones. En este trabajo se presenta el análisis del Colegio de Postgraduados como una experiencia institucional y de vinculación académica. El objetivo principal fue determinar sus capacidades de resiliencia, desde la actuación de sus miembros como comunidad. Se utilizó el enfoque de redes sociales, a través del análisis de las actividades de colaboración académica reportadas por 86 % de la población docente de esta institución, la información obtenida permitió analizar un organigrama social que opera de forma diferenciada y centralizada sobre la base de las vinculaciones de sus investigadores. Con este trabajo, por lo tanto, se propone una línea de investigación que permita analizar estas capacidades en las instituciones mexicanas de investigación en sectores estratégicos, como el agropecuario, a fin de explorar nuevas posibilidades en la gestión del capital intelectual institucional. &lt;/span&gt;&lt;/p&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt;