Study of some resistance mechanisms to Orobanche spp. infestation in faba bean (Vicia faba L.) breeding lines in Tunisia

The behavior of seven faba bean breeding lines toward Orobanche foetida and Orobanche crenata infestation was examined under field, pots, and in vitro conditions and compared to reference cultivars. The breeding lines presented resistance reaction to Orobanche spp. in different experiment conditions. In infested field by O. foetida, the grain yield reduction ranged from 55.7 to 83% for the breeding lines compared to 97% for the susceptible cultivar Badï. Lines L6 and L7 were the less affected by Orobanche parasitism considering severity, number of emerged Orobanche, and yield. In pots, the number of attachments varied from .6 to 3.4 and from 1.4 to 6.4 for the breeding lines against 10.4 and 12.3 for Badï inoculated, respectively, by O. foetida and O. crenata. In Petri dish experiment, Orobanche germination reached the highest rates; 69.9 and 59.7%, respectively, with O. crenata and O. foetida for Badï. For the breeding lines, it ranged from 6.3 to 44.9% for O. crenata and from 4.8 to 40.8% for O. foetida. Moreover, all breeding lines showed low tubercles number and delay in Orobanche attachments as compared to Badï. All breeding lines, except L5, maintained an acceptable level of resistance to Orobanche species manifested by a reduced Orobanche germination rate, low Orobanche number and dry weight, delay of attachments, and higher grain production compared to Badï. L5 seems to be less resistant even it behaves better than Badï in different culture conditions. The studied breeding lines could be recommended as resistance sources or candidates for varieties registrations.