INDUCTION OF RESISTANCE AGAINST DAMPING-OFF AND ROOT ROT DISEASES IN FABA BEAN

Faba bean (Vicia faba L.) seeds cv. Misr 1  were treated with Bion (5 mM), salicylic acid (5 mM) as chemical inducers as well as Paenibacillus polymyxa and Trichoderma harzianum as biotic inducers to study their effect on the infection with Rhizoctonia solani and Fusarium solani f. sp. fabae under greenhouse and field conditions.
          Under greenhouse conditions (Agricultural Research Centre, Giza) all treatments induced reduction in the percentages of pre- and post-emergence damping off caused by R. solani or F. solani f. sp. fabae compared to untreated control. The highest percentage of survived plants was achieved from the inducer Bion (92 % and 88%) compared with untreated control (40% and 36%) in the presence of R. solani or F. solani f. sp. fabae respectively. Meantime, there was no significant difference between the Bion and the fungicide Rizolex –T (3 g/Kg seeds) treatments. However, all treatments caused significant increase in the figures of plant height, shoot and root dry weight, nodules number/plant and nodules dry weight over the control treatment grown in infested soil by R. solani or by F. solani f. sp.  fabae. The highest values of all growth parameters under study were recorded on faba bean plants check (healthy plants) grown in disinfested soil followed by Bion and Rizolex –T treatments in the presence of R. solani or F. solani f. sp.  fabae. There was no significant difference between Bion and Rizolex-T treatments with exception of nodules number and nodules dry weight /plant in the presence of R. solani. On the contrary, there was significant difference between Bion and Rizolex-T treatments with exception of plant height in the presence of F. solani f. sp.  fabae.
          Under field conditions at Giza (Giza Governorate) and Etay El-Baroud (El- Behira Governorate) Agricultural Research Stations during winter season 2013-2014, all the treatments significantly decreased the percentage of pre- and post-emergence damping-off and increased the percentage of survived plants compared with untreated control in two locations with exception of post-emergence percentage figures at Giza Agricultural Research Station. Regarding survived plants, there were no significant differences between the Bion (89.5% and 86.5%) as well as Rizolex-T (90.9% and 88.8%) treatments compared with untreated control (68.3% and 64.3%) at Giza and Etay El-Baroud Agricultural Research Stations respectively. However, all inducer treatments significantly improved growth parameters (i.e. plant height, number of pods/plant, seed weight /plant and one hundred seed weight) as well as yield compared to the untreated control in the two locations. Higher increase in seed yield (ton /feddan) was obtained with Rizolex-T and Bion treatments (62.2% and 57.9%) respectively, followed by salicylic acid and P. polymyxa with (39.4% and 28.4 %) respectively, increasing over the untreated control calculated as means of the two locations.
        Activities of peroxidase (PO), polyphenol oxidase (PPO) enzymes and phenol content were determined in faba bean plants treated with different inducers. Bion treatment showed the highest increase in PO and PPO activity, total and free phenols followed by salicylic acid treatment in the presence of R. solani or F. solani f. sp.  fabae.