Chlorophyll content and chlorophyll fluorescence as physiological parameters for monitoringOrobanche foetidaPoir. infestation on faba bean (Vicia fabaL.)

In total, 39 faba bean ( Vicia faba L.) advanced lines were evaluated for resistance to broomrape Orobanche foetida under highly infested field conditions. The trials were conducted during two consecutive copping seasons at Oued-Beja Research Station in Tunisia. The advanced lines XAR-VF00.13-1-2-1-2-1 and XBJ90.04-2-3-1-1-1-2A expressed high resistance level to O. foetida exceeding those recorded for resistance checks Najeh and Baraca. Results showed that O. foetida significantly affected the biomass, grain yield, chlorophyll content index (CCI) and the maximum quantum efficiency (F v /F m ratio). No significant effect of O. foetida parasitism was observed on host plant water content (WC). O. foetida parasitism significantly affected both CCI and F v /F m ratio. CCI decreases varied from 46.4% for the susceptible check Badi and 4.2% and 9.3% observed for the genotypes Baraca and XBJ90.04-2-3-1-1-1-2A. Compared to susceptible check, slight decreases of F v /F m ratio were observed for both advanced lines XBJ90.04-2-3-1-1-1-2A and XAR-VF00.13-1-2-1-2-1. Correlation between CCI and F v /F m with the resistance to broomrape makes this, easy-to-measure, parameter very useful as a practical screening tool for early parasitism detection, diagnosis and identification and selection of high resistant plants against this pathogen.