Stability Analysis of Egyptian Faba Bean Varieties and their Resilience to Variable Environmental Conditions and Orobanche Parasitic Weed Infestations

Broomrape (Orobanche crenata Forsk.) is an obligatory parasitic weed negatively affecting faba bean hosts grown in the Mediterranean countries. Breeding resistant/tolerant varieties may provide a reliable measure for proper production under infestation. The acceleration of climate change is represented in drastic fluctuations of the elements, greatly impacting the performance of new varieties, particularly in the case of faba reactions to broomrape, which are identified by quantitative genetics.

The results of ten field trials conducted under naturally broomrape-infested soils in the Faculty of Agriculture, Cairo University, Giza, Egypt, during the 2018/2019 and 2019/2020 seasons were used in stability analyses. During each season, five trials were carried out at five planting dates starting at the end of October. In each trial, ten faba bean varieties from different genetic backgrounds and with degrees of reaction to Orobanche infestation were randomly distributed as main plots in RCBD with three replications.

The stability analyses of performance across the twenty environments were performed using three parametric measures: two dynamic (S²d_i and b_i) and one static (CV_i%) stability parameter.

The investigated faba bean cultivars varied significantly in mean performance and stability as measured by all parameters. Based on the ranking of performance by using the centroid method for seed yield plot^-1 or host plant^-1, podded host% and the number of broomrapes, the varieties identified as broomrape-tolerant, particularly the synthetic ones, seemed to be more adaptable across wide environmental conditions and levels of infestation. The seed production of these varieties seems not to be affected across the studied environments in spite of the variable broomrape levels recorded. Thus, for breeding promising and resilient faba bean varieties, lines should be screened under several environmental conditions and those showing reliable performance could be synthesized according to their general combining ability tests.