Plants exposed to suboptimal temperatures suffer damage to physiological processes, growth, development and yield. Acting as enhancers of physiological and metabolic performance of plants, biostimulants have been used to mitigate crop damage caused by abiotic stresses. This study aimed to determine which formulation and dosage of FH Attivus® biostimulant have the best effects on the development of bean plants exposed to suboptimal temperatures (<20 °C). The experiment was conducted in a greenhouse under suboptimal temperatures in a randomized block design with four replications and ten treatments, consisting of three formulations and dosages of the biostimulant, applied at V4 stage, besides a control without biostimulant application. Growth, physiological and biochemical variables were evaluated. The application of biostimulant made bean plants more tolerant to low temperatures by maintaining CO₂ net assimilation rate (A) and increasing the activity of antioxidant enzymes. The relative chlorophyll content (SPAD index), PSII effective quantum yield of linear electron flux (ϕPSII), apparent electron transport rate (ETR) and photochemical extinction coefficient (qP) were higher in all treatments compared to the control, as well as the lowest values of A and ETR were observed in the control. In addition, the activities of all evaluated antioxidant enzymes were superior to the control at the lowest dosages of formulation 2, and at all dosages of formulation 3, indicating, in these treatments, greater protection of cells against oxidative damage. The use of biostimulant is, therefore, a management that makes plants less susceptible to low temperatures in the growing environment.

暴露于次优温度下的植物会遭受生理过程，生长，发育和产量的损害。作为植物生理和代谢性能的增强剂，生物刺激剂已被用于减轻非生物胁迫对作物的伤害。这项研究旨在确定哪种配方和剂量的FHAttivus®生物刺激剂对暴露于次优温度（<20°C）的豆类植物的生长具有最佳影响。该实验是在温室中，亚适度温度下以随机区组设计进行的，除了不施用生物刺激剂的对照外，还进行了四次重复和十种处理，包括三种制剂和剂量的生物刺激剂，在V4阶段施用。评估生长，生理和生化变量。₂净同化率（A）和增加抗氧化酶的活性。与对照相比，所有处理中的相对叶绿素含量（SPAD指数），PSII线性电子通量的有效量子产率（ϕPSII），表观电子传输率（ETR）和光化学消光系数（qP）均较高，最低。A的值 在对照中观察到ETR和ETR。另外，在制剂2的最低剂量下和在制剂3的所有剂量下，所有评估的抗氧化剂酶的活性均优于对照，表明在这些处理中，细胞对氧化损伤的保护作用更大。因此，生物刺激剂的使用可以使植物在生长环境中不易受到低温的影响。