Christopher Paredes

Urochloa brizantha (Brizantha) is cultivated under varying altitudinal and management conditions. Twelve full-sun (monoculture) plots and twelve shaded (silvopastoral) plots were established, proportionally distributed at 170, 503, 661, and 1110 masl. Evaluations were conducted 15, 30, 45, 60, and 75 days after establishment. The conservation and integration of trees in silvopastoral systems reflected a clear anthropogenic influence, evidenced by the preference for species of the Fabaceae family, likely due to their multipurpose nature. Although the altitudinal gradient did not show direct effects on soil properties, intermediate altitudes revealed a significant role of CaCO₃ in enhancing soil fertility. These edaphic conditions at mid-altitudes favored the leaf area development of Brizantha, particularly during the early growth stages, as indicated by significantly larger values (p < 0.05). However, at the harvest stage, no significant differences were observed in physiological or productive traits, nor in foliar chemical components, underscoring the species’ high hardiness and broad adaptation to both soil and altitude conditions. In Brizantha, a significant reduction (p < 0.05) in stomatal size and density was observed under shade in silvopastoral areas, where solar radiation and air temperature decreased, while relative humidity increased. Nonetheless, these microclimatic variations did not lead to significant changes in foliar chemistry, growth variables, or biomass production, suggesting a high degree of adaptive plasticity to microclimatic fluctuations. Foliar ash content exhibited an increasing trend with altitude, indicating greater efficiency of Brizantha in absorbing calcium, phosphorus, and potassium at higher altitudes, possibly linked to more favorable edaphoclimatic conditions for nutrient uptake. Finally, forage quality declined with plant age, as evidenced by reductions in protein, ash, and In Vitro Dry Matter Digestibility (IVDMD), alongside increases in fiber, Neutral Detergent Fiber (NDF), and Acid Detergent Fiber (ADF). These findings support the recommendation of cutting intervals between 30 and 45 days, during which Brizantha displays a more favorable nutritional profile, higher digestibility, and consequently, greater value for animal feeding.

The production system influences the cadmium (Cd) content and mycorrhization in cocoa plantations. The objective of this study was to determine the effects of different production systems on Cd uptake and the presence of mycorrhizas in cacao clones in field conditions, in the Peruvian Amazon. Twelve subplots of 108 m2 were selected in representative cocoa cultivation systems under agroforestry (AF) and monoculture (MON), with the cocoa clones ICS and CCN. Significant differences and data distribution were evaluated using ANOVA, principal component analysis, and Tukey's tests. Mycorrhizal colonization was higher in the AF_ICS system (71.11%) while the length of the extraradical mycelium was higher in the AF_CCN system (17.23%). The highest Cd content in soils was found under the AF_CCN and AF_ICS systems, both with 0.39 mg kg-1. The Cd content in cacao roots, leaves, and beans were higher in the MON_CCN system with 1.87, 2.06, and 1.12 mg kg-1 respectively. Cocoa monocultures (with both clones) generally showed lower levels of mycorrhizal colonization than agroforestry systems, which in turn (also for both clones) presented higher Cd content in beans, even exceeding the limit established by the world health authorities.

La multiplicación de esporas de hongos micorrízicos arbusculares (HMA) es una limitante para las aplicaciones agrícolas como biofertilizantes. En el presente estudio se realizó la multiplicación masiva de HMA procedentes de fincas de cacao (Theobroma cacao L.) en la región de San Martín, Perú, para optimizar su manejo y producción de esporas en condiciones ambientales controladas. Se diseñó un experimento en condiciones de invernadero, con un diseño completamente al azar, considerando tres fuentes de inoculo de HMA obtenidas en las provincias de Mariscal Cáceres, Lamas y Rioja, en dos periodos de tiempo (110 y 220 días) y dos cultivos hospedantes (maíz y arroz). Este material fue mezclado con un volumen de arena y tres de tierra agrícola, que fueron colocadas en cajones; transcurrido el periodo de tiempo se evaluó la población de esporas, colonización micorrícica, altura de la planta hospedante y peso seco de la parte aérea y de la raíz. La multiplicación de HMA a los 220 días, procedente de Mariscal Cáceres usando arroz como planta hospedante, demostró ser la más adecuada para la multiplicación de los HMA. El arroz actuó como un huésped adecuado y pudo multiplicar un mayor número de esporas. Se concluye que esta combinación puede ser utilizada como una metodología de propagación masiva de HMA debido a su gran capacidad para reproducirse.