Synergistic effects of biochar and PGPR modulate peanut physiology and metabolism to mitigate drought stress with reduced synthetic nitrogen

Drought stress is a major constraint for peanut ( Arachis hypogaea L.) production in arid and semi-arid environments. To alleviate drought induced growth and yield losses, farmers often rely on high nitrogen (N) application. However, this approach has economic and environmental concerns. Consequently, there is growing interest in sustainable alternatives such as organic inputs that have great potential to enhance soil water relations and plant performance under limited water availability. This study aimed at optimizing N dose (30, 15, 0 kgNhac − 1 ) with organic sources i.e. biochar (BC) 2% and 1% w/w and Biozote-max (BZ) to improve plant performance under drought. Combined application of BC and BZ integrated with reduced N doses significantly improved root and shoot biomass, leaf area, relative water content, stomatal conductance and chlorophyll content both in frequent and limited water regime than locally practiced 60 kgNhac − 1 . However, integrated application of 2%BC + BZ+15 kgNha − 1 and 1%BC + BZ+30 kgNhac − 1 better maintained counterpart plant water status and gas exchange under drought than in frequent water. Gas chromatography mass spectroscopy (GCMS) analysis of superior performing treatment (1%BC + BZ+30 kgNha − 1 ) revealed activation of hexosamine biosynthesis pathway reflecting primary metabolic adjustments in roots. While high nitrogen application shifted plants to secondary metabolism characterized by upregulation of tyrosine metabolism in roots under drought. Hence, this study demonstrates that integrating biochar, biozote-max and nitrogen particularly 15 or 30 kgNhac − 1 is more effective strategy for alleviating drought effects and sustaining plant primary metabolism in limited water.