الفهرس 
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Abstract
The present investigation revealed the presence of nine soil-borne fungal genera/ species associated within the rhizosphere of horticultural and field plant species plants cultivated at different localities of two counties ( Mansoura and Talkha) in Dakahlia Governorate during the year of 2007/2008. Of them seven fungal genera are considered as plant pathogenic fungi viz. Aspergillus, Alternaria , Fusarium, Penicillium, Rhizoctonia, Stemphyllium, and Rhizopus. However, the filamentous fungus, Trichoderma spp. and the yeast, Saccharomyces spp. are considered as bio-control agents that could be used in pest management programs. In-vitro study revealed the nematicidal properties of such native Trichoderma species against M.incognita . Irrespective to concentrations tested the five species of Trichoderma showed significant inhibition in egg hatching to various extent. The higher the concentrations used the greater extent of inhibition gained. At all concentrations tested, T. harzianum ranked the first and significantly inhibited hatching rate of M.incognita with values of 24.20, 20.17 and 15.29 at 25, 50 and 100% concentrations. However, T. lignorum ranked the second at 50 and 100% concentrations. The impact of Trichoderma species on % of nematode mortality of M.incognita was also undertaken. Irrespective to concentrations and time of exposure all Trichoderma species showed enhancement in the production of nematicidal compounds against M.incognita . After 24 hours of exposure T .koningii ranked the best and showed high % of nematode mortality with values of 47.0, 47.0 and 64.0 % at three concentrations . T.glaucum ranked the second at 50 and 100%.concentrations. Regarding to in – vivo studies two methods of application i.e. soil drenching and seed dressing were undertaken to study the potentials of the five native Trichoderma species viz. T.harzianum, T.hamatum, T.glaucum, T. koningii and T.lignorum for the management of the root-knot nematode, M.incognita infecting three or four economic crops. The fungal antagonist of Trichoderma species applied as soil drench or seed dressing showed successful results and significantly suppressed root-knot nematode, M. incognita population, leading to an enhancement in plant growth parameters of tested plants. Type and species of Trichoderma as well as method of application may be vital factors in effectiveness in both nematode control and the induction of enhanced plant growth . In soil drench application, fungal filtrates of most Trichoderma species at the two concentrations tested 50 and 100%, in addition to the nematicide, oxamyl, showed as good enhancers to plant growth of tested species i.e. sunflower, okra, cowpea and soybean plants infected with 600 freshly hatched ( J2) of M.incognita under greenhouse conditions to various degrees. The highest percentage of increase in total plant fresh weight was recorded in pots receiving T.lignorum ( 121.61) and T.hamatum (120. 14) at 50% on soybean and sunflower respectively . However, the least percentage of increase was recorded with T.glaucum ( 50%) and T. koningii 100% with values of 0.0 and 2.53 % on soybean and okra respectively . It can also be noticed that the leguminous crops i.e. cowpea as well as soybean showed better improvement than other plant species in pots receiving T.lignorum with values of 121.61 , 89.68 respectively and values of 86.24 and 84.52 in pots receiving T. koningii and T.harzianum and cultivated with cowpea respectively under greenhouse conditions at 23 C. The present study stated that more than one species of fungal filtrates of Trichoderma can significantly enhance growth on different plants viz. T.hamatum 50% in sunflower and soybean , T.lignorum 50% in soybean and cowpea , T.lignorum 100% in okra , T.harzianum in soybean ( 100% ) and cowpea (50%) , T. koningii in sunflower ( 50%) and cowpea ( 100%) and T.glaucum 100% in cowpea .On the other hand , fungal filtrates of Trichoderma at two tested concentrations 50 and 100 % and applied as soil drench showed nematicidal properties against M.incognita infecting sunflower, okra , cowpea and soybean with various degrees. On sunflower, most of tested fungal filtrates of Trichoderma in addition to oxamyl significantly suppressed nematode population whether in soil or root as compared to control. The highest reduction in nematode population in soil and root was recorded with pots receiving fungal filtrates of T.harzianum ( 100% ) with reduction percentage reached 76.30% and reproduction factor ( RF) = 0.29 followed by oxamyl ( % Redc. = 75.61 , RF = 0.30) . However , introduction of fungal filtrates of T.glaucum ( 100%) as well as T. hamatum 50% to sunflower inoculated with M. incognita enhanced population density in soil and showed reproduction factor ( RF) = 1.47 and 1.36 respectively compared to control ( 1.21 ) . Meanwhile, the least number of root galling was recorded with T. harzianum 50% with value of 98.65 and RGI= 0.67 followed by T. hamatum at two concentrations 50 and 100 % with percentage reduction reached 97.99 and 97.32 respectively and RGI= 1.0 per each. Oxamyl ranked the third and showed significant reduction in root galling with reduction percentage equal 96.64 and RGI= 1.00 .On okra plant, among all treatments tested oxamyl as nematicide ranked the best and significantly suppressed vermiform nematodes in soil and females in root with reduction percentage amounted to 68.22 and RF= 0.62 . The fungal antagonist , T. lignorum 50% ranked the second followed by T .harzianum 100% with percentage reduction amounted to 59.36 and 58.22 respectively . Root galling and egg masses production were significantly reduced in all treatments tested including oxamyl. The highest percentage of reduction in root galling ( 95.59 %) was recorded with T. lignorum 50% in par with oxamyl followed by T.harzianum 100% ( 92.63%) then T.hamatum 50 % ( 91.18%) . However, no egg masses were observed on roots of okra plant infected with M.incognita following the introduction of T.lignorum 50% . Moreover , T. koningii 50% in par with T.hamatum 50 % and T.harzianum 100% ranked next to T.lignorum 50% and showed % of reduction in egg masses reached 97.8 and EGI amounted to 0.33 for each. On cowpea plant, all treatments of Trichoderma species at two concentrations caused significant suppression in nematode population in soil, females in roots, root galling and egg masses production. The highest significant reduction ( 87.05) in nematode population was recorded with T.lignorum 100% with RF= 0.50 followed by T. harzianum 100 % then T. hamatum 50% with values of 81.30 and 80.32 and RF= 0.72 and 0.76 respectively. However, the highest reduction in root galling was recorded with T.hamatum 100% followed T. koningii 50% then oxamyl with reduction percentage 96.5 and root galling indices 1.00 for each treatment. On the other hand , significant reduction in egg masses production was noticed with all treatments including oxamyl, with no egg masses were observed on cowpea roots treated with T. koningii 50% and oxamyl.On soybean plant, results indicated that almost all species at two concentrations showed significant suppression in nematode population in soil, females in root compared to control. The highest reduction in total nematode population was recorded with T.lignorum 50% with values of 89.57 and RF = 0.18 . However , T.harzianum 100 % ranked next and showed RF= 0.42 . On the other hand , root galling was significantly reduced in all treatments receiving the fungal antagonist , Trichoderma species and oxamyl. The highest reduction in root galling was recorded with T. hamatum 100 % , T.lignorum 50% , T.harzianum 100 & 50 % , T.glaucum 100% and oxamyl with % of reduction equal to 92.11 and RGI = 1.00 . However, no egg masses were observed in soybean roots following the application of Trichoderma species and oxamyl . On the other hand , application of the five native species of Trichoderma as seed dressing revealed that pots receiving Trichoderma species as well as oxamyl significantly suppressed nematode population leading to an enhancement in plant growth parameters of sunflower, okra and cowpea infected with 3000 viable eggs of M.incognita with various extent . Of the native species of Trichoderma , application of T.harzianum as well as T.lignorum and T.glaucum as seed dressing exceeded other treatments of Trichoderma and significantly improved plant growth response with percentage of increase in total plant fresh weight 245.70 , 140.00 and 106.67 on sunflower respectively.