Effects of two rhizobacteria inoculants on maize growth performance at different concentrations of glyphosate

The use of Rhizobacteria as biofertilizer is on the increase due to the ability of some of the bacteria to solubilize some insoluble essential nutrients in the soil and produce phytohormones necessary for plant growth. The effectiveness of two plant growth promoting rhizobacteria (Bacillus cereus and Pseudomonas aeruginosa) in plant growth promotion at different concentrations of glyphosate were evaluated. Some agronomic parameters such as plant height, size of girth, number of leaves on the screen house and field were measured and recorded. The results of the effects of P. aeruginosa on the height of maize at different concentrations showed that the plants inoculated with the isolates and planted on the soil without glyphosate (control) recorded the highest height on the 2nd (34.9 cm), 4th (52.45 cm), 6th (61.17 cm) and 8th (66.25 cm) weeks after planting, when compared to those planted on the soil spiked with different concentrations of glyphosate. The effects of the isolates on the size of girth of maize on the soil spiked with different concentrations of glyphosate showed the highest girth size on the soil inoculated with P. aeruginosa eight weeks after planting (8 WAP) with a girth size of 2.0cm and least at 14.4 mg/ml of glyphosate with a girth size of 1.2 cm at 8 weeks after planting. Similar trend was observed on the soil inoculated with B. cereus (without glyphosate) with the highest girth in the 2nd and 4th WAP (1.02 and 1.42 cm, respectively). The results of our field studies showed no significant difference (P≤0.05) in the height and number of leaves of the maize at different treatments and time (weeks after planting). Similar trend was observed i n the yield of maize. This study has shown that these isolates can be useful as biofertilizers especially in the absence or at low concentration of glyphosate. Keywords: Rhizobacteria, maize, Inoculants, Plant-growth-promotion

Effects of Environmental factors on the Growth and Proliferation of Yeasts

Yeast is one of the organisms that grow and survive in diverse conditions. The influence of environmental factors on its growth and proliferation were evaluated. The yeast used for the study was isolated from honey using Sabouraud Dextrose Agar and pour plate methods. The effects of temperature, pH and ultraviolet radiation on the growth of Rhodotorula, Debaryomyces, Zygosaccharomyces and Candida species were determined using standard methods. The growths of all the yeast isolates were greatly affected at 80oC.  Rhodotorulla species showed least growth at 50oC, but optimal growth was recorded at 30oC after 96 h of incubation. A similar trend was observed in Debaromyces species. Zygosaccharomyces species recorded high reduction in growth at 60oC after 96 h of incubation, though there were no significant differences in the growths of the isolates at 60oC and 80oC. Candida species recorded the least effect of temperature at 30oC and highest at 60oC and 80oC after 96 h of incubation. The results of the effect of pH on growth of the yeasts showed that  Rhodotorula and Zygosaccharomyces had optimum growth at pH of 5 and 4 respectively. All the isolates showed increase in growth with increase in incubation time. Exposure of the isolates to UV-rays negatively affected the growths of the isolates. The growths of the yeasts decreased with increase in exposure time. This study showed that yeast can survive adverse temperature and pH and can as well survive UV-ray exposure