Nitrogen-Fixing Soil Bacteria Plus Mycorrhizal Fungi Improve Seed Yield and Quality Traits of Lentil (Lens culinaris Medik)

Field experiments were carried out in Urmia, Iran to study the effect of biofertilizer application [i.e., nitrogen-fixing soil bacteria (Azotobacter) and mycorrhizal fungi (Glomus intraradices)] on quantitative and qualitative traits of lentil under rainfed and irrigated conditions. The effects of Azotobacter, mycorrhizal fungi, and mycorrhizal fungi plus Azotobacter applied at sowing were assessed on lentil growth under rainfed (i.e., no irrigation during growing season) and irrigated conditions (one irrigation at flowering initiation) compared with control plants (no application of Azotobacter or mycorrhizal fungi). Application of biofertilizers improved leaf moisture content by an average 19.2%, irrespective irrigation level, with the combination of mycorrhizal fungi plus Azotobacter causing the maximum increase (31.1%). Application of biofertilizers improved chl-a and total chlorophyll contents by an average 18.4% and 14.4% under supplemental irrigation, while reduced proline content by an average 14.4% under rainfed conditions and 8.3% under irrigated conditions. Improved biomass yield, seed yield, and seed protein by an average 5.9%, 6.5%, and 20.5% under rainfed conditions and by 24.9%, 21.9%, and 28.2% under irrigated conditions were observed with biofertilizer application compared with control. Plants treated with mycorrhizal fungi plus Azotobacter under supplemental irrigation showed the maximum increase in biomass yield (by 36.9%), seed yield (by 28.4%), and seed protein (by 38.3%). The beneficial effect of mycorrhizal fungi plus Azotobacter on photosynthesis, plant growth, and seed yield can be related to better water and nutrient uptake in lentil plants with application of biofertilizers, particularly under conditions of water shortage. Findings provide novel evidence concerning the effects of certain biological fertilizers on lentil growth and productivity under rainfed conditions, allowing recommendations for improving productivity of lentil cultivation systems in arid and semi-arid areas.