Identification of Host Critical Stage Affected by Orobanche crenata and Variation in the Resistance of Faba Bean Genotypes under Infested Field and Controlled Conditions in Ethiopia

Orobanche crenata is a serious parasitic weed and a major constraint on legume crops, particularly for faba bean, which causes about 75–100% of yield losses in Ethiopia. Twenty faba bean genotypes were evaluated in Orobanche infested fields and pot experiments in Tigray, Ethiopia. The aim of the study was to determine the critical stage of host plants affected by parasite and to evaluate resistance level of faba bean genotypes. The degree of infection and host resistance level was evaluated at three host growing stages (flowering, pod setting, and maturity stages) using different traits like number of Orobanche emerged per plant, per plot, incidence, and severity. The agronomic data such as stand count at emergence, flowering, pod setting, maturity, plant height, pod number, seed per pod, hundred seed weight, and grain yield were recorded from five and three randomly selected plants in the field and pot experiments, respectively. The analysis of variance showed that there were high significant variations p < 0.01 in measured traits between the three host growing stages and between genotypes in agronomic traits. The effect of O. crenata on host plant was started from the flowering stage, but the pod setting stage is economically important stage at which actual effect of the parasite was observed both at field and pot experiments. Based on the result of the study, all tested traits at field and pot experiments allowed separating the faba bean genotypes into three groups: partially resistant and or tolerant genotypes “Ashange, Dide’a, and Obse,” moderately susceptible genotypes “Holleta, Selale, Wayu, Welki, Mesay, Bulga, Degaga, Gachena, Mosise, and Shalo,” and highly susceptible genotypes “Moti, Gebelcho, Dosha, Tumsa, Hachalu, and Tesfa Aloshe.”