Examinando por Autor "Rengifo Sánchez, Raihil Rabindranath"

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Biocontrol and plant growth-promoting potential of Bacillus and actinomycetes isolated from the rhizosphere and phyllosphere of potato (Solanum tuberosum L.) from different agroecological zones of Peru
(MDPI, 2025-12-23) Mamani Rojas, Lizbeth Margarita; Rengifo Sánchez, Raihil Rabindranath; Velarde Apaza, Leslie Diana; Ramírez Rojas, Max; Cántaro Segura, Hector
Potato (Solanum tuberosum L.) is a key staple crop in the Peruvian Andes, but its productivity is threatened by fungal pathogens such as Rhizoctonia solani and Alternaria alternata. In this study, 71 native bacterial strains (39 from phyllosphere and 32 from rhizosphere) were isolated from potato plants across five agroecological zones of Peru and characterized for their plant growth-promoting (PGPR) and antagonistic traits. Actinomycetes demonstrated broader enzymatic profiles, with 2ACPP4 and 2ACPP8 showing high proteolytic (68.4%, 63.4%), lipolytic (59.5%, 60.6%), chitinolytic (32.7%, 35.5%) and amylolytic activity (76.3%, 71.5%). Strain 5ACPP5 (Streptomyces decoyicus) produced 42.8% chitinase and solubilized both dicalcium (120.6%) and tricalcium phosphate (122.3%). The highest IAA production was recorded in Bacillus strain 2BPP8 (95.4 µg/mL), while 5ACPP6 was the highest among Actinomycetes (83.4 µg/mL). Siderophore production was highest in 5ACPP5 (412.4%) and 2ACPP4 (406.8%). In vitro antagonism assays showed that 5ACPP5 inhibited R. solani and A. alternata by 86.4% and 68.9%, respectively, while Bacillus strain BPP4 reached 51.0% inhibition against A. alternata. In greenhouse trials, strain 4BPP8 significantly increased fresh tuber weight (11.91 g), while 5ACPP5 enhanced root biomass and reduced stem canker severity. Molecular identification confirmed BPP4 as Bacillus halotolerans and 5ACPP5 as Streptomyces decoyicus. These strains represent promising candidates for the development of bioinoculants for sustainable potato cultivation in Andean systems.
Soil spatial variability in high-yield Peruvian Amazon coffee: a geostatistical approach for precision fertilization
(Frontiers Media SA, 2025-12-18) Mejía Maita, Sharon Yahaira; Quispe Matos, Kenyi Rolando; Díaz Chuquizuta, Henry; Rengifo Sánchez, Raihil Rabindranath; Mercado Chinchay, Ruth Lizbeth; Cuevas Gimenez, Juan Pablo; Solórzano Acosta, Richard Andi
Fertilization practices in coffee plantations often overlook the spatial variability of soils, particularly in mountainous regions with acidic conditions. Although geostatistics has been used to map nutrient distributions, its integration with multivariate analysis to identify differentiated fertilization zones in coffee systems remains limited. This study evaluated the influence of soil properties, altitude, and crop age on coffee yield by combining principal component analysis (PCA) and ordinary kriging to design site-specific fertilization strategies. A total of 70 soil samples were collected from three districts of the Peruvian high jungle (San Martín and Amazonas), measuring physical and chemical properties, altitude, and crop age. The following analyses were applied: (1) Spearman correlations to assess associations with yield, (2) PCA to identify fertility gradients, and (3) geostatistical models with cross-validation. The PCA identified two main gradients: PC1 (32.41% of variance) associated with cation exchange capacity (CEC) and organic matter, and PC2 (17.88%) associated with the availability of K and P and crop age. Cross-validation confirmed high accuracy in the spatial prediction of available P and K across the three study areas. Kriging maps revealed zones with high available K (>150 mg kg⁻¹) and P (>20 mg kg⁻¹) associated with yields >1.5 t ha⁻¹. The integration of PCA and geostatistics enabled the delineation of management zones with differentiated nutrient requirements, reducing fertilization needs by up to 30% in areas with high fertility potential (e.g., Alto Saposoa). Overall, the results provide a solid methodological basis for implementing precision fertilization strategies in tropical coffee systems, promoting more efficient nutrient use and greater production sustainability.