Soil Amendment Using Biochar and Application of K-Humate Enhance the Growth, Productivity, and Nutritional Value of Onion (Allium cepa L.) under Deficit Irrigation Conditions

Abstract

Water scarcity, due to physical shortage or inadequate access, is a major global challenge that severely affects agricultural productivity and sustainability. Deficit irrigation is a promising strategy to overcome water scarcity, particularly in arid and semiarid regions with limited freshwater resources. However, precise application of deficit irrigation requires a better understanding of the plant response to water/drought stress. In the current study, we investigated the potential impacts of biochar-based soil amendment and foliar potassium-humate application (separately or their combination) on the growth, productivity, and nutritional value of onion (Allium cepa L.) under deficient irrigation conditions in two separate field trials during the 2018/2019 and 2019/2020 seasons. Our findings showed that deficit irrigation negatively affected onion resilience to drought stress. However, these harmful effects were diminished after soil amendment using biochar, K-humate foliar application, or their combination. Briefly, integrated biochar and K-humate application increased onion growth, boosted the content of the photosynthetic pigments, enhanced the water relations, and increased the yield traits of deficient irrigation onion plants. Moreover, it improved the biochemical response, enhanced the activities of antioxidant enzymes, and enriched the nutrient value of deficiently irrigated onion plants. Collectively, these findings highlight the potential utilization of biochar and K-humate as sustainable eco-friendly strategies to improve onion resilience to deficit irrigation.

Collaborative Impact of Compost and Beneficial Rhizobacteria on Soil Properties, Physiological Attributes, and Productivity of Wheat Subjected to Deficit Irrigation in Salt Affected Soil

“…Water stress and soil salinity have together exacerbated a severe ecological threat for agricultural sustainable development which has caused a weakened soil structure, low aeration, surface crusting, high pH, and low filtration rate [ 21 , 38 ]. Moreover, osmotic stress limits water and nutrient uptake resulting in decreased soil enzymes activity and soil physicochemical properties [ 39 ].…”

“…Soil enzymes activity (urease and dehydrogenase) was increased in response to PGPR inoculation which in turn improved root structure, soil particulates, and polysaccharides from microbial cells [ 23 ]. Consequently, an improvement in porosity, aeration, infiltration, and water uptake by roots reflecting positively on plant water status and plant ions was observed [ 21 ]. PGPR could secrete organic acids and phytohormones, acting as biocontrol agents.…”

“…Plants are continuously subjected to changeable abiotic factors, and while these plants are unable to escape from the adverse circumstances, they should either tolerate them or die. In recent decades, scientific research has begun focusing on developing natural and safe substances to enhance plant development, growth, crop productivity, and quality as well as combat harsh environmental conditions [ 21 , 22 ]. Compost and plant growth-promoting rhizobacteria are more ecologically friendly; enhance uptake, absorption, and translocation of nutrients to plant tissues during critical stages of plant growth and development under abiotic stress [ 23 , 24 ].…”

Bread Wheat Productivity in Response to Humic Acid Supply and Supplementary Irrigation Mode in Three Northwestern Coastal Sites of Egypt

“…Effect of HA on wheat seedling growth in the presence and absence of nitrogen (N) was also investigated. Small amounts of HA (54 mg L −1 ) in the water medium resulted in a 500% increase in root length [32]. HA enhanced the fresh and dry weight of roots considerably.…”

Quinoa Response to Application of Phosphogypsum and Plant Growth-Promoting Rhizobacteria under Water Stress Associated with Salt-Affected Soil

“…The combined application of phosphogypsum and PGPR gave higher chlorophyll a, b, and carotenoids contents in leaves. The increase in chlorophyll and carotenoids content in leaves was due to stifled Na and increased Ca and Mg in soil solution as well as decreased Na content and increased K content in the leaves, which helped nutrient uptake and caused water uptake to be easier [ 41 ].…”