Nodulation and nitrogen accumulation in pulses vary with species, cultivars, growth stages, and environments

Biological N-2-fixation underpins the role of pulse crops in the development of sustainable cropping systems, but it is uncertain how nodulation and N accumulation may differ with pulse species, cultivars, and environments. This 3 yr field study investigated nodulation at the early and late flowering stages and seed and straw N uptake for chickpea (Cicer arietinum L.), dry bean (Phaseolus vulgaris L.), faba bean (Vicia faba L.), field pea (Pisum sativum L.), and lentil (Lens culinaris Medik.). At early flowering, all pulses except dry bean had more nodules in the wetter (2010) than drier year (2009). Faba bean had the most nodules followed by field pea and chickpea, while the nodulation varied with plant growth stages and environments. For both pea and lentil, more nodules were observed at early flowering, but higher nodule biomass was obtained at late flowering. Chickpea had higher nodule biomass at late than early flowering but number of nodules varied with year. Seed N uptake was highest in field pea, whereas straw N uptake was highest in faba bean. Our results suggest a possibility of improving pulse N-2-fixation by targeting nodule numbers and nodule biomass, although the outcome of plant N uptake will vary with environments.