الخلاصة:
Abstract
Tomato wilt caused by Fusarium oxysporum f. sp. lycopersici (Lo7) is a serious disease in greenhouses and open fields in the temperate regions of the world. Biological control of the disease using Trichoderma species has been well recognized. The present study investigated the effect of exogenously applied nutrients (NH4, NO3, Sugars, K+, Ca2+, Fe2+ and P+) on conidial germination of T. harzianum (Jn 14) and F. oxysporum f.sp lycopersici (Lo7) in vitro, and in vivo. Furthermore, the increased growth response of tomato plants in the presence of the biological control agent T. harzianum (Jn14) was assessed. In addition to the enzymes production (Chitinases and Glucanases) by T. harzianum (Jn 14), and their effect on conidia germination, and germtube growth of F. oxysporum f.sp lycopersici. The results showed that NO3, Ca2+ and P+, significantly stimulated conidia germination and germtube growth of T. harzianum (Jn14) at concentrations (0.01-1mM), but reduced conidia germination and germtube growth of F. oxysporum f. sp. lycopersici (Lo7) in vitro. Furthermore, NO3, Ca2+, P+ and Fe2+ significantly increased the population of T. harzianum (Jn14), but decreased the population of F. oxysporum f. sp. lycopersici (Lo7) in vivo. In addition, tomato plants growth parameters were stimulated in the presence of T. harzianum (Jn14). Concerning enzyme's production, T. harzianum (Jn14) produced 15% more endochitinases than T. asperllum (T 203), while the later produced 2% more of the exochitinases. In addition, the isolate Jn14 of T. harzianum produced 21% more glucanase than the isolate Jn58. Concerning antibiosis, T. harzianum (Jn14) culture filtrates inhibited conidia germination and germ tube growth of F. oxysporum f. sp. lycopersici (Lo7) at the concentration of 1000 µl/ml in vitro.
