Examinando por Autor "Vallejos Torres, Geomar"

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Carbon stocks in coffee farms and secondary forest systems in the Peruvian Amazon rainforest
(Research square, 2023-09-15) Vallejos Torres, Geomar; Gaona Jimenez, Nery; Ordoñez, Luis; Vallejos Torres, Andi; Mendoza Caballero, Wilfredo; Arévalo, Luis A.; Saavedra Ramírez, Jorge; Macedo, Wilder; Reategui, Keneth; Baselly Villanueva, Juan Rodrigo; Marín, César
Secondary forests and coffee cultivation systems with shade trees might have great potential for carbon sequestration as a means of climate change adaptation and mitigation. This study aimed to measure carbon stocks in coffee plantations under different managements and secondary forest systems in the Peruvian Amazon rainforest (San Martín Region). The carbon stock in secondary forest trees was estimated using allometric equations, while carbon stocks in soil, herbaceous biomass, and leaf litter were determined through sampling and laboratory analysis. The biomass carbon stock in secondary forests was 132.2 t/ha, while in coffee plantations with Inga sp. shade trees it was 118.2 t/ha. Carbon stocks were 76.5 t/ha in coffee with polyculture farming, and the lowest amount of carbon was found in coffee without shade trees (31.1 t/ha). The carbon sequestered by coffee plants in all agroforestry systems examined had an average of 2.65 t/ha, corresponding to 4.63 % of the total carbon sequestered, being the highest stored in the coffee system with Inga sp. shade trees. A higher content of glomalin-related soil proteins (GRSP) was found in coffee without shade trees, with 18.5 mg/g. This is evidence that Inga sp. is the most compatible model of shade system for coffee farms. We recommend the conservation of secondary forests due to the greater biomass and carbon storage, and establishing coffee plantations with Inga sp. shade trees for its integral benefits, such as climate change mitigation.
Evaluación del prendimiento y desarrollo de clones de caucho (Hevea brasiliensis) propagados por injerto en la selva peruana
(Universidad Autónoma de Yucatán, 2024-07-15) Navarro, Jorge M.; Alva Arévalo, Alberto; Lozano, Andi; Alva Arévalo, Celso Misael; García Gonzales, Patricia; Gaona Jimenez, Nery; Baselly Villanueva, Juan Rodrigo; Saavedra Ramírez, Jorge; Vallejos Torres, Geomar
The latex yield in Hevea brasiliensis trees is highly variable; Therefore, it is important to propagate commercial clones of this species by grafting in order to standardize or improve latex yields and therefore improve the economic income of producers in this part of the Amazon region. Objective. To evaluate the attachment and development of rubber clones propagated by grafting in the Peruvian jungle. Methodology. Nine-month-old patterns installed in the field were used. These were grafted with budding rods from the commercial clones TR-1, FX-3864, RRIM-600, IAN-873 and MDF-180. A completely randomized block design was used with five treatments and three blocks with 15 experimental units; each containing 30 repetitions. The data obtained were subjected to analysis of variance and Tukey's multiple range test (p<0.05) and the Kruskal Wallis test. Results. The best results in attachment and number of shoots were obtained in grafts with clone MDF-180 with values of 73.33 % and 7.83 shoots respectively; Regarding days to the appearance of the shoot and length, clone TR-1 presented it with 36.63 days and 27.47 cm; The largest leaf area was presented by the graft with clone IAN-873 with 55.46 cm2, while the highest chlorophyll content was obtained in grafts with clone RRIM-600 with 47.18 SPAD. Implications. More studies are required to establish the quality and adaptability of rubber clones propagated by grafting in different site conditions and establish patterns of tree productivity in a short time; Likewise, it is desired to evaluate the quality and quantity of latex produced by these clones. Conclusions. These results indicate the feasibility of propagating Hevea brasiliensis through shoot grafting in the field, which opens great possibilities for propagating rubber trees with better commercial characteristics, particularly with greater latex production.
Niveles de glomalina y carbono en función de los agregados del suelo en la Amazonía peruana
(Universidad Centroccidental Lisandro Alvarado (UCLA), 2024-09-01) Vallejos Torres, Geomar; Mendoza López, Karla; Ordoñez Sánchez, Luis; Lozano Sulca, Yimi; Gaona Jimenez, Nery; Baselly Villanueva, Juan Rodrigo
La selva amazónica de Perú ha experimentado grandes cambios en el uso de suelos, mediante la deforestación del ecosistema forestal para la instalación de silvopasturas y cultivos agrícolas como café y cacao, lo que ha contribuido al aumento de CO2 en la atmósfera. Este estudio evaluó los niveles de glomalina y carbono en función de los agregados del suelo en estos ambientes. Se estudiaron tres tipos de ecosistemas: i) ecosistema de bosque, ii) agroecosistema de silvopastura y iii) agroecosistema de café. En cada uno se establecieron nueve parcelas de 100 m2 y se extrajeron muestras de suelos a una profundidad de 0-20 cm. Se evaluó el carbono orgánico del suelo (COS) así como la glomalina extraíble (GE) y total (GT), en cuatro diferentes rangos del tamaño de los agregados (>2 mm, 2-1 mm, 1-0,25 mm y 0,25 mm). El efecto del tipo de ecosistema y agregados sobre el COS y glomalina se analizó mediante un ANOVA, así como con una prueba de regresión. Los ecosistemas estudiados influyeron significativamente en la disponibilidad de COS y glomalina; se obtuvo mayor COS en el agroecosistema de café, seguido del ecosistema de bosque con 101,08 y 80,17 t·ha-1. El bosque presentó mayor concentración de GE y GT respecto al cafetal y las silvopasturas. El tamaño de los agregados influyó significativamente en la disponibilidad de COS, GE y GT; cuando fueron de menores dimensiones, los contenidos de COS y glomalina disminuyeron. El tipo del sistema y los agregados del suelo influyeron significativamente en la disponibilidad de COS y glomalina en los tres ambientes estudiados.
Paraglomus occidentale, a new arbuscular mycorrhizal fungus from the sources of the Amazon river in Peru, with a key to the Paraglomeromycetes species.
(Verlag Berger, 2020-02-06) Corazon Guivin, Mike Anderson; Cerna Mendoza, Agustín; Guerrero Abad, Juan Carlos; Vallejos Tapullima, Adela; Ríos Ramírez, Orlando; Vallejos Torres, Geomar; De la Sota Ricaldi, Ana María; Santos, Viviane Monique; Alves da Silva, Gladstone; Oehl, Fritz
A new arbuscular mycorrhizal fungus, Paraglomus occidentale, was found in an agricultural plantation of the inka nut (Plukenetia volubilis) in the Amazonia region of San Martín State in Peru. The inka nut was grown in mixed cultures together with Zea mays and Phaseolus vulgaris. The fungus was propagated in bait and single species cultures on Sorghum vulgare, Brachiaria brizantha, Medicago sativa and P. volubilis as host plants. The fungus differentiates hyaline spores terminally on cylindrical to slightly funnel-shaped hyphae, singly in soils or rarely in roots. The hyaline spores have a triple layered outer wall and a bi- to triple-layered inner wall. They are (59)69–84(92) µm in diameter. The new fungus is distinguished from all other known Paraglomus spp. by spore wall structure including staining characteristics in Melzer’s reagent, which is yellow-grayish to grayish on the outermost and generally dark yellow on the second spore wall layer. Phylogenetically, the new fungus is recognized in a well-separated clade, near to P. laccatum and P. occultum. Finally, an identification key to the Paraglomeromycetes species is included comprising all known species of the genera Paraglomus, Innospora and Pervetustus.
Propagation of Theobroma cacao by rooted cuttings in mini-tunnels
(Hindawi, 2022-04-28) Vásquez Zamora, Lucía Melissa; Rengifo Del Aguila, Sofía; Guerrero Abad, Juan Carlos; Vallejos Torres, Geomar; Imán Correa, Sixto Alfredo; Torres Flores, Elías; Mesén Sequeira, Francisco; Corazon Guivin, Mike Anderson
Cacao is an economically important crop that is currently planted in Asia, Africa, and America. Cuttings is a technique of vegetative propagation suitable for the conservation of selected desirable characteristics in cacao trees. The objective of this study was to evaluate the rooting of cacao cuttings in mini-tunnels with different doses of indole-3-butyric acid (IBA) to obtain a simple and viable vegetative propagation protocol. The experiment was carried out under a completely randomized design (CRD). Cuttings 5 to 7 cm long were collected from the middle area of cacao tree crowns and treated with doses of 0, 1000, 2000, and 3000 ppm of IBA; then they were placed in Jiffy© pellets and set to root in plastic-covered mini-tunnels with fog irrigation. The results indicate that treatments with 0 and 1000 ppm of IBA produced the highest values in survival (100%, both treatments) and rooting percentage (87.7 and 90.0%, respectively) as well as number and length of roots (4.3 roots-4.21 cm in length and 4.5 roots-5.32 cm in length, respectively); likewise, cuttings treated with 0 ppm rooted after 24–40 days, followed by doses of 1000 ppm (24–46 days). All rooted cuttings without IBA (0 ppm) achieved 100% acclimatization in nursery. In general, the best results were obtained without IBA application (Control 0 ppm) in all the parameters evaluated, similar to those obtained with the application of 1000 ppm IBA; these results indicate the success and efficiency of the vegetative propagation protocol proposed in this study.
Soil organic carbon balance across contrasting plant cover ecosystems in the Peruvian Amazon
(Instituto de Investigaciones Agropecuarias, INIA, 2023-10-31) Vallejos Torres, Geomar; Gaona Jimenez, Nery; Lozano, Andi; Paredes, Christopher I.; Lozano, Carlos M.; Alva Arévalo, Alberto; Saavedra Ramírez, Jorge; Arévalo, Luis A.; Reategui, Keneth; Mendoza, Wilfredo; Baselly Villanueva, Juan Rodrigo; Marín, César
The Peruvian Amazon has been significantly affected by land use and climate change, decreasing decomposition processes, which cause a significant depletion of soil C stocks. In this study, we estimated soil organic C (SOC) mediated by different plant covers in coffee (Coffea arabica L.) plantations and secondary forests in several districts of the San Martín Region, Peru. We calculated the critical threshold, saturation point, and the organic C deficit of these Amazonian soils. The association between geography, soil physical-chemical characteristics, and SOC was estimated through principal component analysis. Across all sites of the study, SOC stock had an average value of 69.19 t ha-1, with 48.95 t ha-1 constituting inorganic C. The highest SOC stock (225.28 t ha-1) was observed under secondary forest in the Jepelacio district. The SOC stocks were positively correlated with altitude and CaCO3 content only in secondary forests. The current measured amount of organic C within 15 cm soil depth was 28.5 g C kg-1, which is very low and close to the critical threshold (20.6 g C kg-1) -estimated based on its clay and silt contents. Our SOC stocks measurements indicated a worrisome situation, as they are close to the critical threshold, which exposes this area to a greater and stronger degradation.