الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 187 |  |  |
| | | from | 187 | | |
Abstract
Faba bean (Vicia fabae L.) is considering the most important legume crops in Egypt. It is attacked by many foliar diseases as chocolate spot (Botrytis fabae and B. cinerea), rust (Uromyces fabae), Ascochyta blight (Ascochyta fabae), leaf spots (Cercospora zonata, Stemphylium botryosum and Alternaria alternata), downy mildew (Peronospora viciae) and root rot as well as viral diseases which are responsible to cause considerable losses in the yield and its components.
The obtained results of the present study could be summarised as follows:
1-Surveying of faba bean chocolate spot disease during seasons1998/99 and 1999/00 reveal that, severity % of chocolate spot disease was higher in 1999/2000 than in 1998/99 growing seasons. The highest disease severity was recorded at El-Beheira Governorate (El-Nubaria) while, Qualubia and Beni- Swief Governorates show the least disease severity in both seasons.
2-Isolation of fungi from spotted faba bean leaves during seasons 1998/99 and 99/2000 revealed that Botrytis isolates were the most frequency followed by Alternaria alternata, while Stemphylium botryosum was the lesser one during the two seasons. The highest frequency of Botrytis isolates was recorded at El-Menuofia during the first season whereas; it was recorded at Dakahlia, at the second season. As for tested locations, the highest frequency number of Botrytis isolates
Summary -130-
was recorded at El-Nubaria during the secaned season and Shbeen-El Koum at the first season.
3-Identification of isolated Botrytis isolates indicated that these isolates include Botrytis fabae and B. cinerea isolates. In the first season 1998/1999, B. cinerea occurred at the highest frequency (86.7%); meanwhile, B. fabae was less frequency (13.3%). However, this turned was slightly varied during the second season 1999/2000 where B. fabae and B. cinerea isolates recorded frequency 55.5% and 44.5%, respectively. The highest frequency of B. fabae was recorded at Kleen (Kafr-El Sheikh) during season 1998/1999. In the second growing season 1999/2000, the highest frequency of B. fabae isolate was recorded at Sharkia and El-Beheira Governorates. On the other hand, the highest isolation frequency of B. cinerea was recorded at Menuofia followed by Dakahlia.
4-The tested Botrytis isolates were differed clearly in their virulence onto faba bean leaves (Giza-40) under greenhouse conditions. All isolates of B. fabae were more virulent than B. cinerea ones irrespective of variation within isolates. In this respect, B. fabae (El-Nubaria isolate) was the most virulent
followed by Sakha isolate.
5- RAPD-PCR analysis of the ten isolates of Botrytis spp. (two isolates of B. cinerea and eight isolates of B. fabae) using the specific primer-2-6-d revealed that the ten Botrytis isolates were subdivided into main clusters with similarity 56.45% in between. In this respect, two Botrytis cinerea isolates were distinguished as single strain with high similarity between them. The eight B. fabae revealed different clusters with
Summary -131-
primer-2-6-d, where the similarity was high between isolates 7, 10 and 5. Also, similarity was high between isolates 8 and 9. Isolates 3 and 4 of B. fabae were similar to each but those two isolates were more similar to the B. cinerea isolates than other B. fabae isolates.
6-As for the effect of different media on growth, sporulation and sclerotial formation of tested Botrytis isolates in vitro, faba bean seed agar media (FBSA) was the best favourable medium for growth of all tested Botrytis isolates followed by PDA media and Faba bean leaf agar media (FBLA). Also, growth of B. cinerea isolates was faster than those of B. fabae onto all tested media. As for spore formation, FBLA medium was the best favourable medium for spore followed by FBSA media and PDA media respectively. Most isolates of B. fabae produced number of spores less than isolates of B. cinerea. Regarding sclerotial formation and their size, PDA was the best favourable medium for sclerotial formation followed by FBSA medium. The isolates produced small size of sclerotia in large number were belong to fabae type, while the isolates not producing sclerotia or producing sclerotia large in size but less in numbers were of the cinerea type.
7-All tested isolates were able to grow at all temperature degrees ranging between 10-30°C. In general, temperature ranging from 15 to 20 °C showed the best linear growth comparing with 10, 25 and 30°C respectively. Also, B. cinerea (Sakha isolate), followed by Etay EL-Baroud isolate gave the best growth respectively, while minimum growth was produced by Botrytis fabae (Sakha isolate). Generally,
Summary -132-
isolates of B. cinerea have sporulated more abundantly than B. fabae ones. Botrytis isolates grown on FBLA medium could not be able to sporulate at 10°C. The highest main average of spore number was at 20°C. Increasing spore density increased gradually disease severity. Concerning the effect of spore age on disease severity, the spores of 1 and 2 weeks produced the highest average of disease severity in case of tested isolates of B. cinerea and B. fabae, respectively. Inoculation of detached faba bean leaflets with 3 weeks old spores caused significant reduction in disease severity of Botrytis cinerea and B. fabae isolates. The most suitable plant age for infection with Botrytis fabae was 41 days followed by 65 days old plants when the disease severity was scored 7 days post inoculation. Infection has significantly increased by increasing plant age from 17 to 41 days.