No abstract

One way to mitigate climate change is by reducing atmospheric CO2 levels with the establishment of agroforestry systems (AFSs) that can capture and store atmospheric CO2. This study therefore estimated the carbon sequestration in two components, aboveground (cocoa trees, other tree species, and leaf litter) and soil, in 15 fine aroma cocoa AFSs in Amazonas, Peru. These cocoa AFSs had a minimum area of 1.5 ha and were distributed into three age groups (each group consisted of five systems or farms): young cocoa trees between 8 and 15 years old, middle-aged cocoa trees between 16 and 29 years old, and adult cocoa trees between 30 and more than 40 years old. Generalized linear mixed model (GLMM) analysis followed by Fisher’s LSD mean comparison test (p > 0.05) determined the significant level of total aboveground biomass and total carbon content in the AFSs’ components. The present findings confirm that Theobroma cacao, Mussa sp., Cordia sp., and Persea sp. were the most common species in all AFSs. Clearly, biomass and carbon content in Theobroma cacao and Cordia sp. increased slightly with age, while fruit species Mussa sp. and Persea sp. decreased with age. The total aboveground carbon stock in young cocoa tree systems (13.64 Mg ha−1) was lower than in middle-aged cocoa systems (20.50 Mg ha−1) and adult cocoa systems (24.86 Mg ha−1); nevertheless, no significant differences were found for any of the age ranges. On the other hand, carbon stocks in soil (up to 30 cm depth) in the AFSs ranged from 119.96 Mg ha−1 to 131.96 Mg ha−1. Meanwhile, the total carbon stored by aboveground and soil components in adults cocoa systems (156.81 Mg ha−1) was higher compared to middle-aged cocoa systems (140.60 Mg ha−1) and young cocoa systems (133.59 Mg ha−1), although no statistically significant differences were found. Eventually, the CO2 sequestration for young cocoa systems was 490.28 Mg ha−1, and middle-aged and adult cocoa system recorded more than 500 Mg ha−1 of CO2. Furthermore, these data can further be used by national governments, local governments, and organisations of producers, particularly in accessing payments for environmental services, which may improve economic incomes and contribute to climate change mitigation by reserving biomass and sequestering C from these agroforestry cocoa systems.

Cacao plant cadmium accumulation has become a major concern, especially for small Amazonian producers. A sustainable alternative to address its toxicity is the use of cadmium removal bacteria. In this regard, 138 rhizosphere isolates from cacao were examined. Supported by their phenotypic characterization and in vitro cadmium tolerance, three hypertolerant bacteria were selected and identified as members of the Bacillus (S1C2, R1C2) and Pseudomonas (V3C3) genera. They were able to grow normally and reduce the cadmium content under in vitro conditions. However, only S1C2 and R1C2 evidenced to employ intracellular Cd2+ accumulation, suggesting the variability of bacterial detoxification mechanisms. Their bioremediation capacity for Theobroma cacao CCN51 was also analyzed. Surprisingly, we found high detectable levels of Cd2+ in the non-cadmium supplemented control, suggesting an extra source of cadmium in the pot. Moreover, despite their cadmium reduction performance under in vitro conditions, they exerted highly variable outcomes on stem cadmium accumulation. While S1C2 and R1C2 showed a considerable reduction of Cd content in cacao stems, the strain V3C3 did not show any effect on Cd content. This highlights the complexity of the plant–bacteria interactions and the importance of the in vivo test for the selection of promising PGPR bacteria. Overall, our results suggest the cadmium alleviation potential and promising prospects of native Bacillus strains associated with Amazonian cacao.

<p>El objetivo fue evaluar el carbono total en bosque de tara en suelo, biomasa aérea y hojarasca, en el anexo Señor de los Milagros, distrito de Magdalena (Departamento Amazonas). Para realizar esta investigación se utilizaron 15 unidades muestrales. En la determinación de carbono en suelo se tomaron dos muestras del pie de cada unidad muestral, de 0-0,15m y de 0,15-0,30m. Las muestras fueron llevadas al laboratorio para su análisis. En la determinación de carbono en biomasa aérea y hojarasca se realizó la medición de variables dasométricas antes del derribo y se tomaron muestras de hojas, ramas yfuste, para ser pesados en campo y secados en laboratorio a 75°C. Los resultados obtenidos en el componente suelo fueron de 15,49tC/ha, y biomasa aérea de 64,39tC/ha, equivalente a 56,81tCO₂/ha y 236,12tCO₂/ha, respectivamente. En la determinación de ecuaciones alométricas, se obtuvo que el mejor predictor de biomasa es el DAP, generando relaciones alométricas con R2 mayor a 0.873. La ecuación que mejor se ajusta para estimar el contenido de biomasa seca en tara es la ecuación cuadrática Bt_(kg)=-190,982+61,743*DAP-1,991*DAP2. Finalmente se calculó que los bosques de tara secuestran un aproximado de 34 565,74tCO2/118ha en el distrito de Magdalena, que en términos económicos equivale a US$446 243,70. Esto demuestra que tienen un gran potencial para el mercado de carbono, lo cual sería una fuente de ingresos futura en caso de que se establezcan negociaciones o créditos de carbono.</p>

<p>El objetivo de la investigación fue evaluar los aspectos culturales de 12 cepas nativas de <em>Trichoderma </em>spp. Se llevó a cabo en los ambientes del Laboratorio de LABISANV, de la Universidad Nacional Toribio Rodríguez de Mendoza de Amazonas (UNTRM-A). Donde se evaluó el crecimiento radial del micelio de 12 cepas nativas de <em>Trichoderma </em>spp, en tres diferentes medios de cultivo tales como: Agar Papa Dextroza (PDA), Zezapex Dox Agar (ZDA) y Dricloran Rosa de Bengala (DRB) con tres temperaturas (25 °C, 30 °C y 35 °C). Se empleó un diseño completamente al azar (DCA) con arreglo factorial, con 108 tratamientos y 3 repeticiones por cada uno, con un total de 324 unidades experimentales. Con los datos obtenidos se realizaron análisis de varianza (ANOVA) al 5% de significancia, así mismo se efectuó pruebas de comparaciones múltiples de Tukey al (α ≤ 5 %). Obteniendo como resultados: Las cepas nativas de <em>Trichoderma</em> spp (CP14-5 y CP10-3) fueron las que reportaron el mayor crecimiento radial de micelio con 3.79 cm y 3.69 cm, respectivamente. El medio de cultivo en el que se reportó mayor crecimiento radial de micelio fue, Agar Papa Dextroza (PDA) con 3.78 cm. La temperatura de 30 °C, fue en la que se mostró el mejor crecimiento radial del micelio de las cepas nativas de <em>Trichoderma </em>spp con 3.24 cm. Demostrando de esta menara la influencia que tiene la temperatura y el tipo de medio de cultivo sobre el crecimiento radial del micelio de las cepas nativas de <em>Trichoderma</em> spp.</p>