The biological characteristics of Pseudopeziza medicaginis in alfalfa

Abstract: An experiment was conducted to determine the effect of temperature, humidity, pH, light, carbon sources, nitrogen sources and inorganic salts on pathogenic biological characteristics of Pseudopeziza medicaginis in alfalfa Ningxia strains. This study showed that P. medicaginis of Ningxia strains grew well at the temperature ranging from 5 ℃ to 30 ℃ and the pH value ranging from 4.0 to 10.0, and the optimal temperature and pH value was 20~25 ℃ and 5.0~6.5, respectively. The growth of this fungus was inhibited by the increasing light intensity and it had ability to utilizing different carbon sources on solid medium, especially glucose and maltose. This fungus could use inorganic nitrogen and organic nitrogen source to some extent except for urea, indicating that colonies diameter and growth rate were in accord, but the number of colonies in inorganic nitrogen source was better used than that in organic nitrogen sources. The fungus in three kinds of saline solution shared in increasing common except for KH2PO4, however, apothecium was not observed in 4 saline solutions. Free water on leaf and its maintenance period directly influenced the germination of spore, indicating that the spores germinated when free water on leaf was over 3 hours.