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

Introduction. The sexing of papaya plants (Carica papaya L.) in commercial plantations is usually done visually once the plant emits the flower. There are also biotechnological procedures such as the Polymerase Chain Reaction (PCR), used to detect the sex of papaya at early ages, however, both methods mentioned above present a series of drawbacks, among them false positives. Objective. To identify sex in papaya seedlings using SNP (Single Nucleotide Polymorphism) markers with a high precision. Materials and Methods. The research was carried out at the Fabio Baudrit Moreno Agricultural Experiment Station of the Universidad de Costa Rica, during the months of February to October, 2020. Eight SNP markers were evaluated in papaya plants of known sex using the HRMA (acronym in English: High Resolution Melting Analysis) technique, the best one was chosen and reevaluated in two populations of the genetic improvement program of this crop, then the sexed plants were sown in the field to compare the molecular sexing with the current field sexing. Results. Several of the SNP markers evaluated were polymorphic and could be used to identify sex in papaya, however, the marker CpSERK_HRM_34704 was the one that most closely matched the selection criteria. Conclusion. In the case of the papaya hybrid Pococi and related breeding populations, the marker CpSERK_HRM_34704 showed 100 % precision between the molecular sexing of the seedlings in the nursery using the HRM technique and the current sex of the same plants planted in the field.

 Introduction. Cercospora Leaf blight and Purple Seed Stain are diseases caused by Cercospora kikuchii that affect soybean (Glycine max L. Merr.) worldwide and whose etiological agents are fungi classified in different species certain proximity. Objective. To provide an overview of the pathosystem of Cercospora Leaf blight and Purple Seed Stain caused by Cercospora kikuchii affecting soybean. Development. The degree of severity and/or incidence of both diseases varies in Argentina as well as in the rest of the world. Recent studies showed that there is great variability both morphologically and molecularly among C. kikuchii isolates obtained from petiole and seed in the northern, northern pampas, and southern pampas regions collected in the years 2015 and 2016. The chromosome-level genome of C. kikuchii is available. The genome assembly of 9 contigs is 34.44 Mb and the N50 is 4.19 Mb. Based on ab initio gene prediction, several pathogenicity-related candidate genes were identified, including 242 genes for putative effectors, 55 secondary metabolite gene clusters, and 399 carbohydrate-active enzyme genes. Conclusion. Cercospora Leaf Blight and Purple Seed Stain are endemic diseases in Argentina. The causal pathogen of both diseases shows great genetic and molecular variability in Argentina.

En este estudio se examina el sitio fosilífero Huapilacuy II de edad del Holoceno Medio (7.344±51-6.865± 58 años cal. AP), situado en la costa noroccidental de la isla Grande de Chiloé. Esta área no fue afectada directamente por las sucesivas glaciaciones del Pleistoceno, lo que le otorga relevancia biogeográfica como potencial área de refugio y estabilidad para la vegetación. La presencia de macrofósiles vegetales, contenidos en una secuencia sedimentaria de alrededor de 300 cm de espesor, confiere un especial interés al depósito, debido a la escasa información disponible sobre este tipo de indicadores en los estudios paleoambientales del sur de Chile. Aunque numerosos registros polínicos de la región de Los Lagos (40-44˚ S) documentan, a partir del Holoceno, la recolonización de los distintos bosques templado-lluviosos que hoy ocupan este territorio, no existen registros para el Holoceno en el litoral pacífico de esta región. El objetivo de este trabajo es reconstruir las condiciones ambientales y paleoecológicas locales con base en el contexto estratigráfico y el análisis de los macrofósiles vegetales del sitio Huapilacuy II. Adicionalmente, a partir del análisis polínico del depósito, aportar nuevos antecedentes para la reconstrucción de las características regionales de la vegetación durante el Holoceno Medio. El registro de macrofósiles de especies palustres contenidos en los sedimentos de la parte inferior de la secuencia sedimentaria estudiada, junto con el análisis polínico de la misma, documentan una primera fase de colonización vegetal fechada en 7.344±51 años cal. AP, con predominio de Poaceae, helechos y árboles con capacidad de regeneración en áreas abiertas, como Embothrium coccineum y Drimys winteri. El análisis de los macrofósiles foliares contenidos en varias capas intercaladas en la parte media de la secuencia sedimentaria y el registro polínico del depósito evidencian el desarrollo local/regional de bosques densos, muy húmedos dominados por Aextoxicon punctatum, asociado a varias especies de Myrtaceae. Destaca la presencia de especies indicadoras de humedad edáfica, como Luma chequen, Myrceugenia sp. y Myrtaceae tipo Blepharocalyx, ensamble concordante con las condiciones de sedimentación y desarrollo local de bosques pantanosos o ribereños. Este ambiente de bosque higrófilo es, además, consistente con el ensamble de los musgos fósiles del sitio, en el que predominan taxa correspondientes a los géneros Weymouthia, Ptychomnium, Rigodium, Porothamnium y Eucamptodon, característicos de bosques densos con dosel cerrado. La correlación regional del espectro polínico del sitio Huapilacuy II con otros registros de la región de Los Lagos permite establecer diferencias latitudinales y longitudinales en la composición arbórea de los bosques templado-lluviosos que se expandieron durante el Holoceno Temprano a Medio. En particular, para la costa noroccidental de la isla Grande de Chiloé se establece la presencia de la asociación costera del bosque valdiviano (As. Lapagerio-Aextoxiconetum), distribuida actualmente en el litoral chileno entre los 30 y 43˚ S. En contraste, para otras áreas de la región las asociaciones valdivianas registradas exhiben dominancia de Eucryphia cordifolia, Caldcluvia paniculata, Weinmannia trichosperma y distintas especies de Nothofagus. No obstante, las diferencias en la composición arbórea, las especies de briófitas fósiles registradas en varios de los sitios comparados son comunes con las reseñadas para los bosques de la costa noroccidental de Chiloé, lo que muestra la amplitud ecológica de las briófitas chilenas asociadas a bosques templado-lluviosos perennes con dosel cerrado.

New fossil remains were found in Neogene and quaternary sedimentary sequences exposed in Alpa Corral and río San Bartolomé localities (Rio Cuarto Department, Córdoba, Argentina). They were assigned to Nopachtus cabrerai (Xenarthra, Cingulata, Glyptodontidae), Notiomastodon platensis (Proboscidea, Gomphotheriidae) and cf. Trigodon gaudryi (Notoungulata, Toxodontidae), and traces of the Scoyenia ichnofacies, as Taenidium barretti, were identified. Based on these findings, we conclude that: 1, the species Nopachtus cabrerai and cf. Trigodon gaudryi are registered for the first time in the Sierras Pampeanas region and support (along with the rest of the known taxa) a clear faunistic similarity to the Pampean region; 2, the beginning of the Neogene sedimentation in the Alpa Corral area (Las Barrancas river and San Bartolome river) would have started during the early Pliocene (Montehermosan Age); 3, the paleoenvironment would have been a fluvial system, with meandering canals interspersed with paleosols developed in floodplains with overflow deposits or abandoned meanders; 4, the paleontological and sedimentary record suggests a well-marked diachronism (from west-southwest to east-northeast) between the beginning of the Neogene sedimentation in the southern sector of San Alberto valley (late Miocene [Huayquerian Age]), the Alpa Corral region (early Pliocene [Monthermosan Age), and Río La Cruz valley (late Pliocene [Chapadmalalan Age]).

Introduction. The arracacha is a native Andean tuberous root, with higher productions in Brazil and Colombia. Among the limitations of the crop is the lack of information about reproductive biology (flowering and sexual seed production) stands out, which hinders the breeding of new varieties. The National Germplasm Bank System for Food and Agriculture (SBNAA) of Colombia, under the custody of the Corporacion Colombiana de Investigacion Agropecuaria (AGROSAVIA), conserves 71 accessions of Arracacia xanthorrhiza Bancr., where flowering is frequent in up to 10 % of them. Objective. To characterize the floral structure and describe the reproductive cycle of nine arracacha accessions that flowered between 2019 and 2020. Materials and methods. The study was conducted at La Selva Research Center, Rionegro, Antioquia, Colombia, where the germplasm back is kept. The morphological characterization of the accessions was carried out by recording sixteen variables at the level of floral structure, in addition to monitoring the reproductive cycle. Results. Four groupings were obtained where the variables pollen color, anther color, petal color, plant height, number of staminate flowers, and number of seeds had the greatest contribution to the variability found. The floral reproductive cycle lasted 73 days on average, in which four phenophases were found: 1. umbel emergence, 2. style separation, 3. pollen shedding, and 4. fruit filling, with an average duration of 11, 3, 4, and 55 days, respectively. Among the factors that induced flowering in arracacha were: age, plant genetics, and climate. Conclusion. The floral structures and reproductive cycle of the nine accessions of arracacha that flowered between 2019 and 2020 were characterized.

Introduction. The root-lesion nematodes, Pratylenchus spp., have a wide host range and reduce the yield of different crops. Information on the diversity of Pratylenchus species is scarce in Costa Rica. Objective. To identify the Pratylenchus species associated with 12 crops based on the D3 region of the 28S rDNA gene. Materials and methods. During 2013 to 2015, root samples were collected in Alajuela, Cartago, Guanacaste, Heredia, and San José in crops of rice (Oryza sativa), black pepper (Piper nigrum), sugarcane (Saccharum officinarum), aster (Aster sp.), coffee (Coffea arabica), banana (Musa paradisiaca), lily (Lilium sp.), gypsophila (Gypsophila sp.), onion (Allium cepa), potato (Solanum tuberosum), strawberry (Fragaria x ananassa), and leather-leaf fern (Rumohra adiantiformis). The D3 region of the 28S rDNA gene from each population was amplified and sequenced. A GenBank Blast Search was performed for each sequence. The phylogenetic relationships were established by Bayesian Inference. Results. Blast Search indicated the presence of P. pseudocoffeae in aster, P. brachyurus in black pepper, P. crenatus in onion and potato, P. hippeastri and P. gutierrezi in sugarcane and coffee, respectively. Pratylenchus bolivianus in leather-leaf fern and potato, P. penetrans in onion, strawberry, gypsophila, and lily, P. zeae in rice and sugarcane, while P. speijeri in banana. The phylogenetic analysis corroborated the Pratylenchus species identity with exceptions of sequences from 1) banana, grouped to P. coffeae complex group, 2) sugar cane, grouped to P. hippeastri complex group 3) onion and potato were related with P. crenatus, in an independent group, and 4) leather-leaf fern and potato were grouped with P. bolivianus with low resolution. Conclusions. Nine genetic groups of Pratylenchus were found, some of those should be verified with other molecular markers to get a conclusive identification.

Introduction. Silvopastoral systems play an important role in livestock production, provide benefits to the animal and edaphic components, and offer environmental services such as atmospheric carbon sequestration in the soil and biomass. Objective. To evaluate the capacity of atmospheric carbon sequestration in three systems of different complexities focused on livestock production, in northern Colombia. Materials and methods. The study was carried out at the Turipana Research Center of the Corporacion Colombiana de Investigacion Agropecuaria between 2019 and 2021. The dasometric parameters of the tree/shrub component were evaluated. The aboveground (CBA) and belowground (CBR) biomass of these species were estimated with allometric models. The fallen litter biomass (CLIT) and soil organic carbon up to 30 cm, with readings every 10 cm, were quantified by the combustion method and total accumulated carbon. The design corresponded to complete randomized blocks, with three treatments and four repetitions. The treatments corresponded to two silvopastoral systems (SSP) of different complexity and a grass without trees (Pr). Results. Aerial biomass was higher in the SSP (2.18 ± 1.13, 4.51 ± 3.76 t ha-1 C) than in Pr (0.19 ± 0.09 t ha-1 C). The highest accumulation of CBR (1.16 ± 3.76 t ha-1 C) and CLIT (3.09 ± 2.45 t ha-1 C) occurred in SSP2. The soil organic carbon accumulated (COS) values showed higher accumulation in the first stratum. The COS represented in the three systems more than 70 % of the total contribution in accumulated carbon contribution. Conclusion. Under the environmental conditions of the humid tropical dry forest, silvopastoral systems increased the stock of atmospheric carbon in the soil and biomass. The use of SSP is a strategy in the mitigation of greenhouse gases in the livestock production system.

Introduction. The intensification of agriculture with soybeans (Glycine max L.) as the main component of the productive system causes significant damage to the soil of Argentina and many other parts of the world. Objective. To evaluate the ecological sustainability of four agricultural sequences, under different management of their fallows. Materials and methods. The trial was carried out at the J. Hirschhorn Experimental Station of the Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata (34º 52´ LS, 57º 58´ LO), Buenos Aires, Argentina, where since 2011 four crop sequences have been worked with and, as of 2015, with four different managements of its fallows (control, compost, cover crop without fertilizer and cover crop plus fertilizer). For the sustainability evaluation, five indicators were used: N, P, S, and carbon balance, as well as water use efficiency. The sustainability index was also calculated. Results. The barley (Hordeum vulgare L.) / soybean (Glicine max L.) 2nd - corn (Zea mays L.) - soybean - wheat (Triticum aestivum L.) sequence was the one with the highest sustainability under three of the four management systems. The sequence wheat / soybean 2nd - soybean - soybean - wheat was the one with the lest sustainability for all of the management approaches. Conclusion. The analyzed sequences presented differences in ecological sustainability, which indicates the importance of choosing its components in the search to improve the sustainability of agroecosystems. The use of cover crops in fallows improved sustainability, when associated with greater use of fertilizers and when it was not. The use of compost had a smaller immediate effect since only in the sequence with the highest frequency of soybeans did it produce improvements in sustainability.

Introduction. Basil (Ocimum basilicum L.) is a little-known crop in the Bolivian highlands as its response to water use efficiency (WUE) in a Walipini-type greenhouses. Objective. To evaluate the behavior of two varieties of basil and the water use efficiency (WUE) in the application of foliar biofertilizer in a Walipini-type greenhouse. Materials and methods. The experiment was installed at the Ventilla Ecological Farm, in the Central Highlands of Bolivia, with an experimental period of 135 days (July 13 to November 25), 2014. A factorial experiment with two factors (varieties: Nufar F1 and Italian Large Leaf) and two levels of foliar biofertilizer (Biol) was used under a completely randomized block design. Results. Through the WUE, specific leaf area, and net assimilation rate relationship, it was observed that basil had a better development in Walipini-type greenhouse (underground greenhouse) since biomass accumulation was not significantly affected. The results showed that the production of basil in this environment using foliar biofertilizer, Biol, differ mainly by the variety rather than by the doses of Biol, showing that Nufar F1 had better development. Conclusion. A significant relationship was observed between Nufar F1 and Italian large Leaf for biomass weight when applying Biol at two different levels. It shows that there does not necessarily have to be a positive and significant relationship between biomass accumulation and WUE, so it is presumed that basil can develops regularly in Walipini-type greenhouses under semi-arid region conditions.

Introduction. Agricultural activity is a user and producer of energy, which can be evaluated through energy analysis, which also relates concepts of physics, biochemistry, and biology. Objectives. To evaluate from an expanded energy approach, different commercial models of primary milk production. Materials and methods. The study was based on retrospective data from nine dairy farms in the Pampa´s Argentina Region, between July 2014 and June 2015. Four indicators were calculated: energy output (EE), energy input (IE), energy efficiency (EE/IE), and anergy (A). Results. The highest EE were based on net primary productivity, under high supplementation conditions. The average IE was 239.9 GJ/ha/year, a range in which the systems with medium stocking rates were aligned. Water (67 %) was the main contributor. The efficiency (EE/IE) showed marked variability, based on the IE; although the vegetal biomass was the main cause of EE fluctuation, since the contributions of milk and meat did not differ between systems. The remaining energy stock (storage) was not used within the system, nor did it contribute to the system through its export, so it was defined as a fraction without practical use (A). Conclusions. The energy analysis was a valid tool to evaluate the sustainability of the systems, it was applied in production models with different intensification strategies. When including vegetal biomass, the highest energy outputs (EE) were seen in models with high supplementation, but in the dairy subsystem taken individually, animal stocking rate was associated with higher EE (due to increased productivity) and higher IE, due to the increase of water consumption.