Examinando por Autor "Leiva, Santos"

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Análisis proximal y rendimiento de cinco especies nativas con valor forrajero
(Universidad del Zulia, 2022-01-13) Oliva, Manuel; Meléndez Mori, Jegnes Benjamín; Maicelo Quintana, Jorge Luis; Milla Pino, Manuel Emilio; Leiva, Santos
El objetivo del presente estudio fue evaluar el establecimiento, crecimiento, rendimiento y valor nutritivo de cinco especies nativas con valor forrajero (Cenchrus clandestinus, Philoglossa mimuloides, Philoglossa sp., Trifolium dubium y Trifolium repens). El experimento se realizó en el distrito de Molinopampa (Perú), donde se instalaron parcelas de 30 m2. La altura de planta se midió mensualmente hasta los 90 días. El material se cortó a nivel del suelo, se pesó, se secó y se determinaron los rendimientos de forraje verde y materia seca. El valor nutricional de las muestras se realizó siguiendo el procesamiento de la AOAC. Los resultados muestran que el porcentaje de establecimiento más alto fue alcanzado por T. repens (89,51%). La altura de planta mostró que P. mimuloides y Philoglossa sp. registraron su mayor crecimiento entre los días 30 y 60 después del establecimiento; y además fueron las especies con mayores niveles forraje verde (7,46 y 8,04 kg/m2) y materia seca (8,58 y 8,90 t/ha). En términos de valor nutricional, T. dubium y C. clandestinus registraron los niveles más altos de proteína y fibra, respectivamente; mientras que las especies del género Philoglossa tienen mayor digestibilidad.
Effect of Endophytic Trichoderma sp. Strains on the Agronomic Characteristics of Ecotypes of Theobroma cacao L. under Nursery Conditions in Peru
(Hindawi, 2022-05-24) Chavez Jalk, Antony; Leiva, Santos; Bobadilla Rivera, Leidy Gheraldine; Vigo Mestanza, Carmen Natividad; Arce, Marielita; Oliva Cruz, Manuel
Peru is one of the main producers of fine aroma native cacao, expanding its areas considerably in recent years, which makes it necessary to seek adequate management alternatives to obtain advantageous yields. The present work had the objective of testing the influence of Trichoderma sp. endophytic strains on the agronomic characteristics of ecotypes of Theobroma cacao L. under nursery conditions, Cajaruro district, Utcubamba, Amazonas, Peru. The Trichoderma strains evaluated were Trichoderma breve; T. harzianum; T. longibrachatum; T. afrojarzianum, and Trichoderma sp. which were inoculated on cocoa seedlings of ecotypes CCN51; TCHS565; and nativo fino de aroma. The variables evaluated were chlorophyll indices (at 30, 45, 60, and 70 days after planting), percentage of endophyte colonization, root hair development, trichomes on stems, and agronomic characteristics (plant height, number of leaves, stem diameter, root dry and fresh weight, root size, etc.). The results showed that the application of Trichoderma breve in the fine aroma native cocoa ecotype (T12) presented the highest chlorophyll index at 75 days after planting (DAP) with 43.53 +- 1.59 and 49.77 +- 2.42 for the apex and leaf base, respectively, with a percentage of colonization in the root hairs of 66.67%, and with better characteristics for the number of leaves with 12.00 +- 3.46. T12 showed positive influences for plant height, leaf number, and chlorophyll index. Treatments based on T. harzianum + CCN51 (T5) and T. afroharzianum + TSHS565 (T6) showed 100% colonization of the root hairs and trichomes on stems. Endophytic Trichoderma fungi are an alternative for organic production of fine aroma cocoa in Peru, improving the agronomic characteristics of the crop.
In vitro biological activity of Beauveria bassiana, Beauveria peruviensis, and Metarhizium sp. against Hypothenemus hampei (Coleoptera: Curculionidae)
(Hindawi, 2023-09-30) Chuquibala Checan, Beimer; Torres de la Cruz, Magdiel; Leiva, Santos; Hernandez Diaz, Elgar; Rubio, Karol; Goñas Goñas, Malluri; Arce Inga, Marielita; Oliva Cruz, Manuel
Coffee (Coffea arabica) is the main commodity in Peru and is the economic support for thousands of small farmers. However, coffee production is affected by the coffee berry borer (Hypothenemus hampei). Currently, H. hampei is the most important pest in whole coffee-growing regions in Peru. This study aimed to evaluate in vitro biological activity of Beauveria bassiana, Beauveria peruviensis, and Metarhizium sp. against Hypothenemus hampei in two trials at different times. Conidia production, Conidia viability, and pathogenicity against H. hampei were evaluated at three concentrations (1 × 105, 1 × 107, and 1 × 109 conidia/mL−1). In addition, lethal times (LT50 and LT90) and lethal concentrations (LC50 and LC90) were calculated. There were significant differences in conidia production ( < 0.001) and conidia viability ( < 0.041). The highest conidia production and conidia viability were reached by B. bassiana and B. peruviensis, respectively. Likewise, there were differences in the pathogenicity of the strains in the two tests carried out (test 1: < 0.0009 and test 2: < 0.0001). The highest mortality occurred in the treatments of B. bassiana 1 × 109 conidia/mL−1, B. bassiana 1 × 107 conidia/mL−1, and B. peruviensis 1 × 109 conidia/mL−1. The treatments with lower LT50 and LT90 were B. bassiana 1 × 109 conidia/mL−1 and B. peruviensis 1 × 109 conidia/mL−1, and the strains with the lowest LC50 and LC90 were B. peruviensis and B. bassiana. The in vitro characteristics shown by B. bassiana and B. peruviensis conditions suggest they should be evaluated in the field to determine the capability of these strains to reduce populations of H. hampei.