Challenges and promising opportunities for biostimulants application in sustainable agriculture

To sustain the growing human population within current incoming climate challenges, it is imperative to enhance both the quality and yield of crops to ensure global food security with a focus on sustainability. Modern agricultural practices and future perspectives for agricultural systems are more critical than ever, as they aim to minimize environmental and human health impacts stemming from the widespread use of mineral fertilizers and chemical products intended to improve crop yield and quality. In this context, biostimulants emerge as a promising solution to mitigate these issues and provide a renewable option for fostering sustainable agricultural development. Biostimulants contain various bioactive compounds that promote plant growth and development, improve nutrient uptake, and enhance stress tolerance to maintain an environmentally sustainable approach. They also promote the degradation and humification of organic substances in soils, making them environmentally friendly resources. Additionally, several natural-based biostimulants are derived from microorganisms such as bacteria, fungi, or microalgae, which play a crucial role in promoting plant growth and development by colonizing the rhizosphere and facilitating nutrient uptake and synthesis of plant hormones. Biostimulants were initially employed in organic agriculture for high-value horticultural crop production but have now gained traction in conventional crop production due to their demonstrated ability to enhance plant productivity and quality. This manuscript aims to critically review the challenges and promising opportunities associated with the application of biostimulants to promote sustainable agriculture. It will delve into various aspects including concepts, principal sources, roles in enhancing nutrient uptake and recovery, morpho-physiological and biochemical changes in plants, crop yield, and quality, and the main uses in mitigating abiotic and biotic stresses under climate change scenarios.