Volatile and gaseous metabolites released by germinating seeds of lentil and maize cultivars with different susceptibilities to fusariosis and smut.

The effect of volatile and gaseous metabolites released by germinating seeds of lentil cultivars more and less susceptible to fusariosis on the germination of spores of Mucor racemosus, Trichoderma viride, Verticillium dahliae and Botrytis cinerea was found to depend rather on the fungal genus than on the lentil cultivar. However, spores of Fusarium oxysporum reacted more sensitively during germination to the presence of exudates of both cultivars, when the more susceptible lentil displayed a stimulation, the less susceptible one an inhibition of spore germination. The greatest difference in the effect of exudates was observed in the more and less susceptible maize cultivars with respect to the germination of chlamydospores of Ustilago maydis, especially during the first hours of seed germination. Analysis of the exudates of germinating seeds showed the release of a greater amount of ethanol and methanol with acetaldehyde by the more susceptible cultivars of lentil and particularly maize.

Effect of volatile and gaseous metabolites of germinating pea seeds on Micromycetes.

Differences in the effect of volatile and gaseous metabolites of germinating pea seeds on the germination of spores of Mucor racemosus and macroconidia of Fusarium oxysporum are described. Germination of spores of M. racemosus was inhibited by seed metabolites whereas germination of macroconidia of F. oxysporum was stimulated during the first two days and inhibition occurred only after further two days of germination of the seeds. A pronounced inhibition of germination of spores of both micromycetes took place due to absorption of CO2 from volatile and gaseous metabolites. Absorption of some components of seed metabolites in a KMnO4 solution led to a decrease of the inhibitory effect on germination of spores of M. racemosus and stimulatory effect on germination of macroconidia of F. oxysporum.

Rhizosphere mycoflora of wheat after foliar application of chlorocholine chloride, urea and 4-chloro-2-methylphenoxyacetic acid.

A single-step spraying of wheat during shooting under field conditions with solutions of CCC (chlorocholine chloride), CCC and urea, CCC and Aminex (ammonium salt of 4-chloro-2-methylphenoxyacetic acid), or CCC, urea and Aminex caused changes both in numbers and composition of the rhizosphere mycoflora. The numbers both in the rhizosphere of differently treated plants and in the free soil decreased during vegetation. A more pronounced effect in the number of fungi was demonstrated in plants treated only with CCC. The difference was more considerable during first 10 days after the spray. As far as the relative occurrence of individual genera in the rhizosphere soil is concerned, fungi of the genera Penicillium Link ex Fr., Fusarium Link ex Fr., Verticillium Nees and Trichoderma Pers were most influenced after the treatment with the used agents.

The effect of volatile and gaseous metabolites of swelling seeds on germination of fungal spores.

Effects of volatile and gaseous metabolites of swelling seeds of pea, bean, wheat, corn cucumber, tomato, lentil, carrot, red papper and lettuce on germination of spores of five genera of fungi were found to depend rather on the fungal than on the plant genus. Germination of spores of Botrytis cinerea, Mucor racemosus and Trichoderma viride was most severely inhibited. Spores of Verticillium dahliae were less sensitive and germination of spores of Fusarium oxysporum was inhibited only in two cases. On the other hand, exudates of pea and bean stimulated germination of spores of Fusarium oxysporum. Also spores of Trichoderma viride germinated better in an atmosphere enriched with exuded metabolites of swelling lettuce seeds. When carbon dioxide produced by the swelling seeds was absorbed in potassium hydroxide, spores of Trichoderma viride and Verticillium dahliae did not germinate at all, the inhibitory effects of volatile and gaseous exudates on germination of spores of Mucor racemosus were accentuated, and also the percentage of germinated spores of Fusarium oxysporum decreased. Germination of spores of Botrytis cinerea was not influenced. Absorption of volatile and gaseous metabolites in a solution of potassium permanganate decreased in most cases their inhibitory effects, particularly in Botrytis cinerea.