اثر دما، pH و منابع غذایی بر فعالیت آنتاگونیستی Acrophialophora jodhpurensis. علیه Alternaria alternata

The genus Chaetomium is a cosmopolitan and endophytic fungus, which some of its species have antagonistic activity against phytopathogens. In this study the effect of temperature, pH, various carbon and nitrogen sources and amino acids on antagonistic activity of Acrophialophora jodhpurensis (Chaetomium jodhpurense Lodha), isolated from tomato root was investigated in dual culture against Alternaria alternata. The effects of temperature (15, 17, 20, 24, 28, 30, 35 and 37◦C) and pH (4, 5, 6, 7, 7.4, 8 and 9) were investigated on 2% potato dextrose agar (PDA) medium. Effect of various carbon sources, such as starch, dextrose, fructose, sucrose with 1% concentration also 1% and 0.5% concentration of glucose was investigated. The carbon sources were added to half-strength potato agar medium. The highest level of antagonistic activity was observed in the presence of glucose at 0.5% concentration. Therefore, the half-strength potato agar medium with 0.5% glucose was selected as the basal medium for investigating the influence of different nitrogen sources and amino acids. Effect of different nitrogen sources, such as sodium nitrate, ammonium sulfate, uric acid, ammonium chloride, ammonium phosphate at 0.033% concentration in each case and amino acids such as glycine, arginine, leucin, asparagine, serine and phenylalanine at 1 gL-1 concentration were investigated. Radial growth of the fungal pathogen was determined when the control petri dishes were covered with the pathogen’s mycelia. Each experiment was repeated three times with three replications for each repetition. Results showed the higher antagonistic activity of A. jodhpurensis against A. alternata at pH 7, temperature of 30 ̊C, in the presence of the amino acid asparagine, and sodium nitrate was found to be the best nitrogen source.