Competition for nutrients between phytopathogenic and antagonistic soil fungi
2001
Celar, F. | Kac, M. (Ljubljana Univ. (Slovenia). Biotechnical Fac., Agronomy Dept.)
Five phytopathogenic fungi were used in the experiments, three of the Fusarium genus (F. solani, F. sambucinum, F. moniliforme) together with Rhizoctonia solani and Sclerotinia sclerotiorum. Of five agonistic fungi tested, four belong to the Trichoderma genus (T. longibrachiatum, T. harzianum, T. viride, T. koningii), additionally Gliocladium roseum was included in the study. The results of the experiments show that compared to the phytopahogenic fungi, in most cases the antagonistic fungi are capable of using the nitrogen as ammonium at statistically significant higher rates during the first six days of cultivation. Further on, it has been shown, that they begin by using the nitrogen as ammonium and switch to the nitrate form of nitrogen when the former is being nearly used up. As far the nitrogen in the nitrate form is considered, the situation is reversed: in most cases the phytopathogenic fungi of the Fusarium genus perform a statistically significant quicker use of the nitrogen in the form of nitrate compared to the antagonistic fungi. The fungi R. solani and S. sclerotiorum first use nitrogen in the form of ammonium and if this one is getting short, they switch to the nitrate form of nitrogen. The fungi from the Fusarium genus use the two sources of nitrogen simultaneously. Even at the beginning, when there is plenty of nitrogen in the ammonium form available they use the nitrite form of nitrogen at the same time. Owing to the rate of using glucose from the growth medium the phytopathogenic fungi can be divided into two groups compared to the antagonistic fungi. The fungi from the Fusarium genus use the glucose at much higher rates compared to the antagonistic fungi. Fungi S. sclerotiorum in R. solani behave differently since their rates of using the glucose from the growth medium are statistically significantly lower.
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