The use of natural plant growth regulators (PGRs) as ecofriendly agrochemicals is gaining much attention, but the fate of these compounds once they enter the soil environment is poorly understood. In this work, we compared the plant growth inhibitory activity of the phytohormone S-abscisic acid (S-ABA) in the presence of three soils with that observed in soilless (Petri dish) conditions and related the differences in activity to the sorption and dissipation processes of the phytohormone in the soils. In Petri dishes, S-ABA inhibited the germination of Eruca sativa, Allium porrum, Lactuca sativa, and Hordeum vulgare with mean inhibitory concentration values (IC₅₀) in the range of 0.5–8.2 mg/L. Eruca sativa was selected for subsequent studies based on its high sensitivity to S-ABA (IC₅₀ = 0.5 mg/L). The inhibition of germination of E. sativa by S-ABA was fully reversible at a low phytohormone concentration (5 mg/L) and partially reversible at a higher phytohormone concentration (60 mg/L). S-ABA also inhibited the growth of pre-germinated seedlings of E. sativa, albeit at higher concentrations than those at which it inhibited germination. The three soils used in the study weakened the inhibitory activity of S-ABA by soil factors in the range of 0.008–0.380. As S-ABA displayed low or even negative sorption in the soils tested, the decrease in the activity of S-ABA was attributed to its biodegradation in the soils, rather than to a decrease in its bioavailability due to sorption. Despite the reduction in the activity of S-ABA observed in the presence of the soils, the phytohormone still expressed its activity at quite low soil concentrations (0.3–20 mg/kg), showing higher activity in soils where the compound degraded more slowly.

天然植物生长调节剂（PGR）作为环保农用化学品的使用受到广泛关注，但人们对这些化合物进入土壤环境后的命运知之甚少。在这项工作中，我们比较了三种土壤中植物激素 S-脱落酸 (S-ABA) 的植物生长抑制活性与无土（培养皿）条件下观察到的植物生长抑制活性，并将活性差异与吸附和消散联系起来土壤中植物激素的过程。在培养皿中，S-ABA 抑制 Eruca sativa、Allium porrum、Lactuca sativa 和 Hordeum vulgare 的发芽，平均抑制浓度值 (IC ₅₀ ) 在 0.5–8.2 mg/L 范围内。由于 Eruca sativa 对 S-ABA 具有较高的敏感性（IC ₅₀ = 0.5 mg/L），因此选择 Eruca sativa 进行后续研究。 S-ABA 对苜蓿发芽的抑制在低植物激素浓度（5 mg/L）下是完全可逆的，在较高植物激素浓度（60 mg/L）下是部分可逆的。 S-ABA 还抑制 E. sativa 发芽前幼苗的生长，尽管其浓度高于抑制发芽的浓度。研究中使用的三种土壤在0.008-0.380范围内削弱了土壤因子对S-ABA的抑制活性。由于S-ABA在测试的土壤中表现出低甚至负吸附，因此S-ABA活性的降低归因于其在土壤中的生物降解，而不是由于吸附而导致其生物利用度降低。尽管在土壤存在下观察到 S-ABA 的活性降低，但植物激素在相当低的土壤浓度（0.3-20 mg/kg）下仍然表现出其活性，在化合物降解较慢的土壤中显示出更高的活性。