Self-inhibition of Germination of Pycnidiospores of Mycosphaerella ligulicola in Relation to the Temperature of their Formation

At high concentrations, self-inhibition of germination of pycnidiospores of Mycosphaerella ligulicola increased with rise in temperature at which the spores were formed.

Spores formed at 15° (15° spores), which showed little self-inhibition at high concentrations, and 26° (26° spores), which showed marked self-inhibition at high concentrations, were used for experiments. Mixing 15° spores equally with 26° spores increased inhibition of the latter but the former were unaffected. Leachates from 15° and 26° cultures did not affect germination of 26° and 15° spores respectively, but germ tubes of 15° spores showed increased growth. Inhibition of 26° spores was overcome by washing ten times with deionized water and germ tube growth from washed spores was increased in culture leachates. Diffusates collected from dense suspensions of 26° spores did not affect germination. Diffusates from 15° spores prevented germination of 26° spores but not 15° spores where growth of germ tubes was increased. The inhibitory substance from 15° spores was not readily volatile and not affected by high temperature in solution. Volatile inhibitors were not detected from either 15° or 26° spores. Pfeffer 1 % glucose solution overcame self-inhibition of 26° spores but 1 % glucose or Pfeffer solution alone were ineffective.