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Phenology of the Alien Invasive Plant Species Prosopis juliflora in Arid and Semi-Arid Areas in Response to Climate Variability and Some Perspectives for Its Control in Ethiopia

Shiferaw Wakshum, Bekele Tamrat, Demissew Sebsebe, Aynekulu Ermias

Polish Journal of Ecology

2020

Vol. 68, nr 1

37--46

This study aims to (i) evaluate the phenology of Prosopis juliflora (Prosopis), (ii) investigate the effects of climate variability (temperature and precipitation) on the phenology of Prosopis, and (iii) assess the critical months of seed dispersal for the species management. Monthly data for phenology events: leafing, flowering, green and mature pods were collected from 8 stems of Prosopis trees at each of two localities in Ethiopia during 2016/2017. In Amibara district we found that relative abundances of green leaves, flowering, green pods, and mature pods were 91, 15, 9, and 2% in order. However, these were less than by 8, 53, 91, and 90%, respectively in Awash Fenatle district. The lowest proportions of mature and green pods were recorded in the dry season and the highest in the spring season. We recorded the highest and lowest relative abundances of flowering between November and December, and January and February, respectively. In this study, both temperature (F = 2.01, P = 0.04) and precipitation (F = 2.85, P = 0.01) had shown significant effects on the relative abundances of green leaves but insignificant effects on other phenology stages. Higher green leaf abundances were recorded during high rainfall, whereas lower abundances of leaves were recorded in high temperatures. But, the relative abundances of Prosopis leaves showed inconsistent with the variations of precipitation. Thus, awareness creation for stake holders about the phenology calendar of Prosopis should be given to abandon the invasiveness of the species towards the prime grazing lands in the region.

Ultrasound assisted green synthesis of cerium oxide nanoparticles using Prosopis juliflora leaf extract and their structural, optical and antibacterial properties

Arunachalam T., Karpagasundaram U., Rajarathinam N.

Materials Science Poland

2017

Vol. 35, No. 4

791--798

Cerium oxide nanoparticles (CONPs) were prepared using ultrasound assisted leaf extract of Prosopis juliflora acting as a reducing as well as stabilizing agent. The synthesized CONPs were characterized by ultraviolet-visible absorption spectroscopy (UV-Vis), particle size analyzer (PSA), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). From the UV-Vis analysis, the optical band gap of the prepared CONPs (Eg = 3.62 eV) was slightly increased as compared to the bulk ceria (E g = 3.19 eV). The phytochemicals in the extract reduced the particle size to 3.7 nm ± 0.3 nm, as it is evident from the PSA. FT-IR results confirmed the Ce-O stretching bands by showing the peaks at 452 cm-1. The Raman spectrum showed a characteristic peak shift for CONPs at 461.2 cm-1. XRD analysis revealed the cubic fluorite structure of the synthesized nanoparticles with the lattice constant, a of 5.415 Å and unit cell volume, V of 158.813 Å3. XPS signals were used to determine the concentration of Ce3+ and Ce4+ in the prepared CONPs and it was found that major amount of cerium exist in the Ce4+ state. HRTEM images showed spherical shaped particles with an average size of 15 nm. Furthermore, the antibacterial activity of the prepared CONPs was evaluated and their efficacies were compared with the conventional antibiotics using disc diffusion assay against a set of Gram positive (G+) bacteria (Staphylococcus aureus, Streptococcus pneumonia) and Gram negative (G-) bacteria (Pseudomonas aeruginosa, Proteus vulgaris). The results suggested that CONPs showed antibacterial activity with significant variations due to the differences in the membrane structure and cell wall composition among the two groups tested.