Selection for Nitrogen Fixation Increases Yield in Faba Bean

Abstract

Improving biological nitrogen fixation (BNF) through plant breeding is a potential approach to increase seed nitrogen yield in faba bean. Previously two cycles of bidirectional recurrent phenotypic selection were conducted for a BNF index combining nodule number, nodule mass, acetylene reduction activity, and plant fresh weight (Sadiki, 1990). This research was conducted to determine responses to plant selection for BNF. Inbred lines were derived after 5 selfing generations from resulting subpopulations (MGP-H1, MGP-H2, MGP, MGP-L1, and MGP-L2) and used to evaluate selection response. The field evaluation was conducted in 3 environments (Tadla 1994, Tadla 1995, and Meknès 1994) with inoculation using the same inoculum used in the greenhouse. The data showed that the subpopulations generally ranked accordingly to the selection direction (Table 1). The subpopulations selected for high BNF maintained their superiority over the parental gene pool and over the subpopulations selected for low BNF. For both cycles selection progress was higher for increased than for reduced BNF potential. Selection for increased BNF potential resulted in significantly increased seed nitrogen content and yield. This research demonstrated that BNF was heritable and that it was possible to change BNF potential in faba bean through plant selection. Faba bean with increased BNF provides more plant N for rotations including cereals which are predominant in the Maghreb region. Cultivars with increased BNF potential will provide a significant economic impact on agricultural systems in many Moroccan marginal regions and on sustainable cropping systems in developed agricultural systems.KeywordsInbred LineFaba BeanSelection DirectionField EvaluationPlant SelectionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.