Contribution in isolation and identification of some pathogenic fungi from wheat seeds, and evaluation of antagonistic capability of Trichoderma harzianum against those isolated fungi in vitro

Abstract

The aim of this study was to isolate and to identify the pathogenic fungi accompanying interior in hard wheat seeds, and to evaluate the antagonism capability in vitro of (Trichoderma harzianum) against those pathogenic isolated fungi. Three samples of local hard wheat seeds (Triticum durum Desf) were brought from Oum-elbouaghi (Algeria) silos yields, follower for varieties: Vitron, Waha, and Cirta. ).They were stored for one year. The results of isolation on potato-dextrose agar (PDA) medium and after identification of fungal accompanying interior in the seeds clarified about (83) fungus isolates following for species next : Fusarium acuminatum (1 isolate) in a ratio of (1.2%), and Alternaria(82 isolates) with a ratio of (98.795 %).The Alternaria isolates apportioned among two species: Alternaria alternata with 39 isolates(12 isolates for: Alternaria alternata1 and 27 isolates for : Alternaria alternata2) and Alternaria infectoria with 43 isolates).And, besides it was clearly seen that the Cirta variety was a lowest infected with fungi(19 isolates) in ratio of (22.89 %), and both varieties Waha and Vitron with(32 isolates)for each one in a ration equal (38.554 %) . The results of the antagonistic capability in vitro of (Trichoderma harzianum) against isolated fungi, showed that: 1- The direct confrontation in vitro of Trichoderma harzianum against the different fungus isolates on PDA medium, showed that: a In the fourth day of the experiment, Trichoderma harzianum inhibited the mycelia growth of different pathogenic fungi in dual cultures, with different ratios, it was equal to: 6.66% for Fusarium acuminatum, and 23%, 26.66% and 40% for Alternaria alternata1, Alternaria alternata2, and Alternaria infectoria, respectively. b-The microscopic observations of the different interactions hyphal between Trichoderma harzianum and different fungus isolates, showed that the antagonistic fungus affected on Alternaria species with the decomposition phenomenon (Lyses), where it analyzed the mycelia and spores of Alternaria altrenata2 and Alternaria infectoria, while it analyzed the mycelia of Alternaria alternata1, compared with control. 2- The remote confrontation in vitro of Trichoderma harzianum against the different fungus isolates on PDA medium showed that : a- The volatile metabolic substances of Trichoderma harzianum affected the growth of the different pathogenic fungi, with different ratios over the seven days of treatment, compared with control.b- The microscopic observations Noted that the volatile metabolic substances of Trichoderma harzianum affected some isolated fungi with mycelia analysis prevent the spore's formation of the Alternaria alternata2, while stopped the spore formation of Fusarium acuminatum, compared with control