INFLUENCE OF PRIMEXTRA AND GLYPHOSATEON THE RHIZOSPHERE MICROORGANISMS OF COWPEA (VIGNA UNGUICULATA) AND THEIR ABILITY TO SOLUBILIZE PHOSPHATE

Abstract

Four different concentrations of both primextra at (0.00, 3.00, 5.00, 7.00ml) and glyphosate at (0.00, 0.50, 1.00, 3.00)ml were separately applied to the soil at the back of the Department of Crop, Soil and Pest Management, Akure, Federal University of Technology Akure,Nigeria.15 days after application, cowpea seedlings were planted and were harvested after 30days of germination. Microorganisms from rhizosphere treated with glyphosate and primextra were cultured and identified using selective media (Wakesman A and B agar). The isolates were screened for inorganic phosphate solubilization and production of phosphatases.There were decrease in the bacterial and fungal population in the rhizosphere of cowpea as both glyphosate and primextra concentrations increased. Bacillus subtilis, B. cereus, Klebsiellapneumoniae, Proteusmirabilis,Escherichia coli,Serratia marcescens, Staphylococcus aureus,Micrococcus luteus, Aspergillus niger, Penicillum italicum, P. notatum and Articulosporium inflata were isolated from primextra treated soil while Bacillus cereus, B. subtilis, B. pumilis Micrococcus luteus, Pseudomonas aeruginosa, Proteus mirabilis,Staphylococcus aureus, Aspergillus flavus, Rhizopus nigrifican, Gonatobotryumapicola, Varicosporiumelodes, Trichodermaviride and Mucormucedo were isolated from glyphosate treated soil. The concentration of the solubilized tricalcium phosphate ranged from 97.87 to 559.47ug-1.Among all the organisms isolated from the untreated soil of primextra, only B. subtilis, M. luteus, S. aureus, K. pneumonia, showed general increase in the amount of solubilized phosphate (AMSP) and also among all the organisms isolated from the rhizosphere treated with low concentration of primextra, none of the bacteria showed increase in the amount of solubilized phosphate (AMSP) while at low concentration there was reduction in pH. There were increases in solubilized phosphate with increase in concentration of primextra.Proteus mirabilis isolated from Primextra treated soil showed the highest phosphatase activity of 27.719mM/min/ml at 30hrs while the lowest phosphatase activity of 3.86mM/min/ml at 6hrs was seen in Klebshiella aerogenes. Highest protein concentration of 31.724mg/ml at 30hrs was seen in Proteusmirabilis and lowest protein concentration of 0.55mg/ml was shown inBacillus cereus isolated from Primextra treated soil.Also, among the fungi isolated from Primextra treated soil, Articulosporium inflata showed highest phosphatase activity of 23.157mM/min/ml at 72hrs and highest protein concentration of 26.206mg/ml at 36hr. Proteus mirabilis isolated from glyphosate showed the highest phosphatase activity of ( 23.157mM/min/ml ) at 30hrs and the lowest activity of (8.771mM/min/ml) at 6hrs.Highest protein concentration (9.93mg/ml)at 24hr was shown in Bacillus cereus and B. subtilis had the lowest protein concentration (3.034mg/ml)at 12hr. Also ,among the fungi isolated from glyphosate treated soil, Aspergillus saprophyticus showed highest phosphatase activity (35.263mM/min/ml) at 72hrs and Aspergillus flavus had lowest activity (2.28Mm/min/ml )at 12hr. Rhizopus nigrificanhad highest protein concentration of (33.931mg/ml) at 36hr while Aspergillus flavus had lowest protein 10.482mg/ml at 12hr.