Biostimulants are products that reduce fertiliser requirements while also stimulating plant growth and protecting crops from abiotic stress by increasing tolerance. Biostimulants such as algal or other plant extracts, protein hydrolysates, humic and fulvic acids, and other enhanced combinations have been shown to promote further growth and stress adaptability. These outcomes consist of higher yield, enhanced nutrient absorption and utilization, increased photosynthetic activity, and tolerance to both biotic and abiotic stressors. While most biostimulants have a variety of effects on plant growth, this chapter concentrates on bioprotective effects against abiotic stress. Biostimulants have the potential to make agriculture more sustainable and resilient, as well as provide an alternative to synthetic protectants, which have proven increasingly unpopular with consumers. In this regard, this chapter seeks to discuss the specific function of biostimulants that have defensive effects against abiotic stress, but also highlights the urgent need to investigate the underlying processes that cause these benefits.

生物刺激素是减少肥料需求的产品，同时还可以通过增加耐受性来刺激植物生长并保护作物免受非生物胁迫。生物刺激素，如藻类或其他植物提取物、蛋白质水解物、腐殖酸和黄腐酸，以及其他增强的组合，已被证明可以促进进一步的生长和压力适应性。这些成果包括更高的产量、增强的养分吸收和利用、增加的光合活性以及对生物和非生物胁迫的耐受性。虽然大多数生物刺激剂对植物生长有多种影响，但本章重点介绍针对非生物胁迫的生物保护作用。生物刺激剂有可能使农业更具可持续性和复原力，并提供合成保护剂的替代品，事实证明，这些产品越来越不受消费者欢迎。在这方面，本章旨在讨论对非生物胁迫具有防御作用的生物刺激剂的特定功能，但也强调迫切需要研究导致这些益处的潜在过程。