Alleviation of water limited stress in the grass pea (Lathyrus sativus L.) through arbuscular mycorrhizal fungi and rhizobium bacteria symbiosis

Grass pea ( Lathyrus sativus L.) is a considerable leguminous crop, but its growth and development are astricted by drought, which is intimidatory to grass pea production especially in arid or semiarid regions. Farmers are currently adopting good agricultural practices in the crop production. When producing forage, bio organic nutrients are being considered as a better alternative to chemical fertilizers. Here, two consecutive-year of experiments were conduct to investigate the efficiency of bacteria and arbuscular mycorrhizal fungi in changing the growth and yield related traits of grass pea under different irrigation regimes (well watered, mild and severe limited water conditions). The results demonstrated that the unfertilized and stressed plants had the lowest performance of grass pea, while plants inoculated with biofertilizers performed the best. The limited water caused a decline in total chlorophyll content (20.3%), leaf area index (20.32%), relative water index (5.5%), seeds/pod (2.9%), pods/plant (20.23%), 1000-seed weight (2.92%), pod harvest index (0.72%), seed yield (24.5%) and biological yield (17.69%) relative to well-watered treatment, over two years. Rhizobium bacteria inoculation enhanced contents of relative water, seeds/pod, 100-seed weight, biological yield and pod harvest index by average of 9.25%, 4.82%, 4.81%, 16.78% and 1.36%. Moreover, arbuscular mycorrhizal fungi inoculation increased the relative water content (7.7%), seeds/pod (3.8%), 1000-seed weight (3.9%), pod harvest index (1.04%) and pod partitioning index (13.9%). It can be concluded that application of a mixture of biofertilizers belonging to different groups could be a beneficial method and show a positive effect on the ​productivity of grass pea under limited water conditions.