الفهرس 
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Abstract
The present work aimed to evaluate the suppressive effect of certain composts (CMS) on incidence of root rot and wilt diseases of faba bean, to enhance suppressiveness of CMC on diseases by yeast seed treatment and to investigate the mechanism(s) by which CMS suppress such diseases.
Results of the study can be summarized as follows:
1- Twenty one isolates of fungi (4 of R. solani, 6 of F. subglutinans, 3 of each of F. oxysporum and F. nygamas, 2 of each of F. verticilliodes and F. proliferatum and one of F. babindo) were isolated from diseased faba bean plants collected from Assiut counties and showing root rot and wilt symptoms.
2- They proved to be pathogenic on Masr 1 faba bean cv. under greenhouse conditions. F. oxysporum isolates caused wilt disease however, isolates of R. solani and other Fusarium species caused root rot. Virulence of isolates on the tested faba bean cv. was different. The highly pathogenic isolates No. II of each of R. solani and F. subglutinans (the incitant of root rot) and No. I of F. oxysporum (the incitant of wilt) were employed in further studies.
3- Testing the effect of soil amendment with Planta Rich and Rich Composts (CMS) on severity of Rhizoctonia and Fusarium root rot and Fusarium wilt of faba bean was tested under greenhouse and field conditions. Soil was artificially infested with the causal fungal pathogens and supplemented with different rates of CMS equivalent to 2, 7, 10 and 14 T/F before sowing Masr 1 faba bean cv. Uncomposted soil was used as control. Results showed that the tested CMS have a suppressive effect on severity of root rot and wilt diseases of faba bean under greenhouse and field conditions.
In general, the tested rates of CMS had different suppressive effects on incidence of root rot and wilt diseases, however, the two types of CMS caused similar effects on disease severity percentage. Application of the high rates of CMS (10-14 T/F) to soil caused the highest reduction percentage in severity of Fusarium root rot and Fusarium wilt in greenhouse and the field followed by 7 T/F then 2 T/F, while, raise the tested rates of CMS from 2 up to 14 T/F did not affect reduction percentage in severity of Rhizoctonia root rot disease.
4- Under field conditions, treated soil with the two types of CMS (Planta Rich and Rich) and the pathogenic fungi caused pronounced increase in plant growth parameters (plant hight, fresh weight/plant, number of branches/plant, number of pods/plant and fresh weight of pods/plant) of Masr 1 faba bean cv. Increment percentage of the tested plant growth parameters varied by types of CMS, CMS rate and pathogenic fungi.
Supplemented soil with the lowest CMC rates (2 & 7 T/F) caused the highest plant hight and fresh weight/plant, in case of soil infested with Fusarium wilt or Rhizoctonia root rot fungi, however, the opposite trend was true for plant weight in case of soil infested by Fusarium root rot fungus. On the other hand, raise CMS rates from 2 up to 14 T/F had no effect on percentage of increment in plant hight or number of branches/plant. Results also show that in soil amended with the two types of CMS, the tested fungi affected significantly number of branches/plant. The highest number of branches/plant was recorded in soil infested with F. oxysporum, followed by that infested with other tested fungi.
Number of pods/plant was increased in plants grown in soil infested with R. solani and supplemented with 2 and 7 T/F CMS and that infested with F. oxysporum and treated with 7 and 10 T/F CMS. However, pods fresh weight/plant was increased in all tested CMS and fungal treatments. Supplemented infested soil with root rot pathogens with 2 and 10 T/F CMS and that infested with Fusarium wilt fungus with 2, 7 & 14 T/F CMS caused the highest increase in pod fresh weight/plant followed by other tested treatments. Increment percentage of number and fresh weight of pods/plant were different by different types of CMS, tested rates of CMS and fungal species.
5- Studies on enhancement of suppressive effect of CMS on severity of root rot and wilt diseases of faba bean by yeast treatment under greenhouse and field conditions revealed the following:
a- Pichia gluilliermondi yeast isolate No. V proved to be highly antagonistic to growth of R. solani and F. subglutinans and F. oxysporum (the incitants of root rot and wilt diseases, respectively) was selected for seed treatment.
b- Application of CMS (Plant Rich and Rich) alone at the rates equivalent to 2, 7, 10 and 14 T/faddan in greenhouse experiment and 7 and 10 T/F in the field to the soil infested with the tested pathogens reduced percentage of diseases and increased percentage of plant growth compared with uncomposted soil.
c- Combined CMS treatments with yeast seed treatment enhanced the suppressive effect of CMS on disease severity and caused much more increase in plant growth compared with CMS treatments alone.
d- The tested CMS proved to be similar in their effect on disease severity or plant growth.
6- To investigate the mechanisms by which Planta Rich and Rich CMS suppress root rot and wilt of faba bean, influence of soil amendment with CMS on population density of Bacillus spp., fluorescent Pseudomonas, Actinomycetes and fungi in soil, enumeration of antagonistic microbs in the two types of CMS, and determination of pathogenesis-Related Protein(s) in faba bean plants associated with soil suppressiveness were studied. Results can be summarized as following:
6.1- determination of soil microbial activity in composted soil:
a- Soil amendment with the two types of CMS at different rates equivalent to 2, 7, 10 and 14 T/F increased population densities of Bacillus spp., fluorescence Pseudomonas, Actinomycetes and fungi in soil infested with the root rot and wilt of faba bean pathogens compared with uncomposted soil.
b- Total counts of microorganisms in soil infested with pathogens after 30 or 60 days from planting date were higher than that recovered from soil at time of planting (after 7 days from soil infestation and CMS treatments). The total counts of bacteria and actinomycetes in different tested treatments were higher than that of fungi.
c- Raise the tested rate of CMS from 2 up to 14 T/F increased, in most cases, total numbers of bacteria and actinomycetes, however the total numbers of fungi were decreased, especially in the second counting date.
d- Population density of the tested soil microorganisms was slightly affected by the types of tested compost, while it was strongly affected by soil infestation with pathogens. The highest numbers of bacteria and Actinomycetes and the least numbers of fungi were detected in composted soil infested with Rhizoctonia solani followed by Fusarium oxysporum and finally F. subglutinans.
6.2- Enuemration of antagonistic microorganisms in suppressive CMS indicate the following:
a- Population of Bacillus, fluorescent Pseudomonas, Actinomycetes and fungi were different in Planta Rich and Rich CMS. Planta Rich CM have the highest population of such microbs compared with Rich CM except in case of Bacillus. Planta Rich CM showed also higher microbial activity determined by FDA hydrolyses method than Rich CMS.
b- Out of 39 isolates of Bacillus, fluorescent Pseudomonas, Actinomycetes and certain fungi belongs to the genera Aspergillus, Penicillium, Gliocladium, Rhizopus, Fusarium and Acrophiolphora, 29 isolates proved to be antagonistic to growth of root rot and wilt fungi of faba bean, in vitro. The antagonistic effect of these isolates to growth of pathogens was different and varied from weak to strong.
6.3- Electrophoratic analysis of extracts of healthy and infected faba bean plants of Masr 1 cv. (by root rot and wilt fungi) grown in infested soil with the tested pathogens and supplemented with the suppressive CMS (Planta Rich or Rich) at the rate of 10 T/F was done to determine pathogenesis-related proteins associated with the suppressive effect of CMS. Results show the following:
a- Nineteen protein bands were detected with molecular weight (MW) ranged from 16.3 to 67.5 KDa. Protein Pands No. 5 and 7 with MW 44 and 42.3 KDa, respectively, were induced by Rich CM treatment, however, Planta Rich CM treatment induced Pand No. 7 only. Induction of protein Pand No. 13 (MW 23.3 KDa) was only associated with fungal infection in composted soil.
b- Sex chitianse bands (Chit-2, Chit-3, Chit-4, Chit-5, Chit-7 and Chit-8) were detected in healthy and diseased plants grown in composted soil. However, Chit-1 and Chit-6 isoforms were induced in composted soil infested with the tested fungi.
c- Sex peroxidase bands (PRX-1, PRX-2, PRX-3, PRX-4, PRX-6 and PRX-7) were detected in extracts of healthy and diseased faba bean plants grown in soil supplemented or not supplemented with suppressive CMS. However, PRX-5 isoform was induced only in diseased plants grown in composted soil.
d- Seven esterase bands (ESt-1, ESt-2, ESt-3, ESt-5, ESt-6, ESt-7 and ESt-8) were detected in healthy and diseased plants grown in composted soil. The ESt-4 isoform was detected only in diseased plants grown in soil treated with Rich CM.