Induce Biotypes From The Biocontrol Fungus Trichoderma harzianum Tolerant To Salinaty

Abstract

The study was carried out in order to evaluate about the concentration of NaCl that inhibit growth of the fungus Trichoderma harzianum Rifai and gaining a new biotypes tolerant to high levels of saline stress for using it as a biological control agent for plants pathogens endemic in the soil in the region of high salinity Result showed that the concentration 128.8 mmol/L of NaCl inhibit completly the radial growth of parently strain on czapek solid medium , We obtained 34 biotypes of the fungus Trichoderma harzianum grown on Czapek solid medium that treated with concentration 128.8 mmol /L of sodium chloride after exposure fungus spores suspention to Ultraviolet ray at a wavelength 320 nm for six exposure times (5, 10, 20, 40, 80, 160) minutes, Among 34 new biotypes, responded three biotypes only (Th5, Th26, Th33) to the increase of the concentration of NaCl in the Czapek solid medium and for level of 508.4 mmol/L, even though these biotypes have responded in different ways to the increase in salt concentration , the concentration 128.8 mmol/L caused reduction in the rate of radial growth were 8 ,22 ,23 % , with respect to dry weight of viable mass, the concentration 115.2 mmol/L caused reduction in the dry weight were 0.092, 0.066 0.073 gm /50ml , With respect to sporulation the concentration 101.6 mmol/L caused reduction in the rate of production of spores was 1300 x105, 1000 x105, 1100 x105 spore/ml With respect to the viability of spores, the concentration 94.9 mmol/L caused reduction in the spores viability were 10 ,19 ,17 % in the new biotypes Th5, Th26, Th33 respectively.