Abstract: This study evaluates the antibacterial, cytotoxic activities, and phytochemical composition, of Callistemon citrinus, Hibiscus rosa-sinensis and Plumbago auriculata leaves and flowers, three ornamental plants in Mexico. However, in other countries offers a range of other uses. Ethanol extracts of C. citrinus leaf and flower presented stronger antibacterial activity than the extracts obtained from the other two plants. C. citrinus leaf showed low cytotoxicity (LC50 <600 µg/mL) on the brine shrimp test, whereas the ethanol extracts of H. rosa-sinensis and P. auriculata leaves showed no cytotoxic activity. Flower extracts obtained from the three plants did no exhibit cytotoxicity. GC-MS analysis revealed that the ethanol extract of P. auriculata leaf contained lupeol triterpene and lupeol acetate, neither of them have been previously reported in this genus. Gamma sitosterol was present in the leaf and flower extracts of P. auriculata. Higher contents of linoleic and linolenic acids were found in extracts of H. rosa-sinensis leaves and flowers. The ability of the ethanol extracts of C. citrinus leaves and flowers to inhibit the growth of Gram-positive and Gram-negative bacteria indicates a potentially broad antimicrobial spectrum. Moreover, the absence of cytotoxicity suggests the potential use of this plant to treat microbial infections.

Abstract The arbuscular mycorrhizal fungi (HMA) are a biological alternative to increase the absorption of phosphorus and reduce the excessive use of phosphate fertilizers. The objective of this work was to evaluate the effect of different concentrations of phosphorus fertilization on avocado plants with and without mycorrhiza. A factorial design was used with two factors: mycorrhizal inoculant (with three levels: Rizofermic-UV, Pacispora scintillans and uninoculated) and fertilization with phosphorus (with five levels: without fertilizer, 20, 40, 80 and 160 ppm; using H2PO4 as fertilizer source), each treatment with four replicates. 401 days after inoculation, height, diameter, number of leaves, leaf area, growth rate, fresh and dry weight and percentage of mycorrhizal colonization were evaluated. Variables were analyzed using a Fisher’s test, with a significance level of p< 0.05. being considered significant. The treatment with 160 ppm caused the death of the plants at 150 days, while inoculated seedlings plus 20 ppm showed an increase in significant growth variables (p< 0.05) with respect to the control. Both plants inoculated with Rizofermic-UV and P. scintillans showed a significant increase in growth variables with respect to the control (p< 0.05). The plants inoculated with P. scintillans and also with a treatment of 20 ppm of phosphorus, promote the greatest increase in growth variables. Mycorrhization had positive and significant effects on the development of the inoculated plants compared to the control plants.

Resumen Los hongos micorrízicos arbusculares (HMA) son una alternativa biológica para aumentar la absorción del fósforo y reducir el uso excesivo de fertilizantes fosfatados. El objetivo de este trabajo fue evaluar el efecto de diferentes concentraciones de fertilización fosforada en plantas de aguacate con y sin micorriza. Para el experimento se utilizó un diseño factorial con dos factores: inoculante micorrízico (con tres niveles: Rizofermic-UV, Pacispora scintillans y sin inocular) y fertilización con fósforo (con cinco niveles: sin fertilizante, 20, 40, 80 y 160 ppm; utilizando H2PO4 como fuente de fertilizante), cada tratamiento con cuatro repeticiones. A 401 días después de la inoculación se evaluó altura, diámetro, numero de hojas, área foliar, tasa de crecimiento, peso fresco y seco y porcentaje de colonización micorrízica. Las variables se analizaron con una prueba de Fisher, considerando significativo un valor de p< 0.05. El tratamiento con 160 ppm causó la muerte de las plantas a los 150 días, mientras que plántulas inoculadas más 20 ppm mostraron un incremento en variables de crecimiento significativo (p< 0.05) con respecto al testigo. Tanto plantas inoculadas con Rizofermic-UV como con P. scintillans mostraron un incremento significativo en variables de crecimiento con respecto al testigo (p< 0.05). Las plantas inoculadas con P. scintillans y además con un tratamiento de 20 ppm de fósforo, promueven el mayor incremento en las variables de crecimiento. La micorrización tuvo efectos positivos y significativos sobre el desarrollo de las plantas inoculadas respecto de las plantas control.