Co-Application Of Biochar And Arbuscular Mycorrhizal Fungi Improves Salinity Tolerance In Cereal Grains (Triticum Aestivum L. And Zea Mays L.) And Mitigates Aluminum Toxicity In A Forest Species Of Tamarind (Tamarindus Indica L.)

Increasing salinization is a growing threat to worldwide agricultural productivity that is made worst by soil acidification and/or drought.The decrease in agricultural productivity has led to increasing food insecurity and the inability of most countries in the developing world to practice sustainable agriculture has made this matter worst.Thus,this study was designed in the first place to evaluate the mitigating effects of biochar and/or Arbuscular mycorrhizal fungi（AMF）on grain crops grown in saline-infested alkaline soil and secondly to investigate how similar treatments could improve the growth of an forest species Tamarindus indica under conditions of Al stress in an acidic soil.Study one reports on the mitigating effects of biochar（5%）,Arbuscular mycorrhizal fungi（20 g/pot,AMF,Glomus mosseae）,and biochar+AMF on maize（Zea mays L.）and wheat（Triticum aestivum L.）plants grown under saline stress in a greenhouse.The plants were grown on alkaline soil and subjected to four different saline levels;0（CK）,50（S₁）,100（S₂）,and 150（S₃）m M Na Cl.For maize,after 90 d in 100 m M Na Cl control treatment（S₂）,the plant’s height and fresh weight were reduced by 17.84%and 39.28%,respectively,compared to CK.When the saline-treated soil（100 m M Na Cl）was amended with AMF（A₂）,biochar（B₂）,and biochar+AMF（AB₂）,the growth parameters were increased by22.04%,26.97%,30.92%（height）and 24.79%,62.36%,and 107.7%（fresh weight）,respectively.Compared to CK and single AMF/biochar treatments,the combined application of biochar and AMF showed the most significant effect in improving maize growth under saline stress.This increment was also similar for the wheat plant under similar conditions.The superior mitigating effect of biochar+AMF was attributed to its effective ability in（i）improving soil nutrient content,（ii）enhancing plant nutrient uptake,（iii）increasing the activities of antioxidant enzymes,and（iv）increasing the levels of membrane unsaturation by improving the contents of palmitoleic acid（C16:1）,oleic acid（C18:1）,linoleic acid（C18:2）,and linolenic acid（C18:3）.Thus,this study shows that amending alkaline-saline soils with a combination of biochar-AMF can effectively mitigate abiotic stress and improve plant growth.Study two is a 90 d greenhouse pot experiment that was conducted to evaluate the efficiency of soil amendments with biochar and/or three Arbuscular Mycorrhizal Fungi（AMF）strains;Glomus fasciculatum（Gf）,Glomus aggregatum（Ga）,and Rhizophagus irregularis（Ri）,on T.indica grown under Aluminum stress.The amendments consisted of5%biochar and 20 g kg^-1 AMF as（i）control;（ii）biochar;（iii）biochar+Gf;（iv）biochar+Ga;（v）biochar+Ri;（vi）Gf;（vii）Ga;（viii）Ri.The treatments with biochar significantly（P<0.05）increased soil p H and reduced the content of soil exchangeable Al³⁺relative to the control and exclusive AMF treatments.All the treatments improved total nitrogen and phosphorus uptake by roots and shoot of T.indica which resulted in improved plant growth and root/shoot dry weight.The ability of biochar to enhance the soil’s water-holding capacity played a vital role in improving the intensity of mycorrhization.Overall,biochar amendments significantly improved the photosynthetic potential of T.indica and the activities of antioxidant enzymes compared to other treatments.Thus,the combined effects of enhanced（a）soil physicochemical parameters,（b）mycorrhization,（c）nutrient uptake,（d）photosynthetic potential,and（e）antioxidant activities played an important role in mitigating Al-related stress to improve the growth of T.indica.Therefore,the application of biochar in combination with AMFs can serve as a strategy for ensuring plant biodiversity in acid and Al-toxic soils in arid and semi-arid regions in Africa.