Basil, renowned for its aromatic properties, exhibits commendable drought tolerance and holds significant value as an edible and medicinal plant. Recognizing the scarcity of studies addressing basil’s response to drought stress, we performed physiological experiments and omics analyses of sweet basil across four distinct levels of drought stress. During drought stress, basil showed increased activity of antioxidant enzymes and accumulated more osmoregulatory compounds. Our metabolic analysis meticulously identified a total of 830 metabolites, among which, 215 were differentially accumulated. The differentially accumulated metabolites under drought stress were predominantly esters and terpenes; however, none were identified as the primary volatile compounds of basil. Transcriptome analyses highlighted the pivotal roles of phenylpropanoid and flavonoid biosynthesis and lipid metabolism in fortifying the resistance of sweet basil against drought stress. α-linolenic acid, lignin, flavonoid, and flavonol contents significantly increased under stress; the essential genes involved in the production of these compounds were confirmed through quantitative real-time PCR (qRT-PCR), and their variations aligned with the outcomes from sequencing. This holistic approach not only enriches our understanding of the molecular intricacies underpinning basil’s drought resistance but also furnishes valuable insights for the molecular breeding of basil varieties endowed with enhanced drought tolerance.

Kenaf (Hibiscus cannabinus L.) is considered suitable for the remediation of cadmium (Cd)-contaminated farmlands, because of its large biomass and resistance to Cd stress. The addition of nitrogen (N) fertilizer is an important measure used to increase crop yields, and it may also affect Cd accumulation in plants. To clarify the effects of different forms and concentrations of N on plant growth and Cd absorption in kenaf, a hydroponic experiment was conducted using three N forms (NH₄⁺–N, NO₃⁻–N and urea–N) at four concentrations (0, 2, 4 and 8 mM, 0 mM as control) under Cd stress (30 μM). The plant growth, the antioxidant enzyme activity and the Cd contents of various parts of the kenaf seedlings were measured. The results showed that the N form had the greatest impact on the growth of the kenaf and the absorption and transport of the Cd, followed by the interaction effect between the N type and the concentration. Compared to the control, the addition of N fertilizer promoted the growth of kenaf to varying degrees. Among all the treatments, the use of 2 mM of NO₃⁻–N enhanced the biomass and Cd accumulation to the greatest extent compared to CK from 2.02 g to 4.35 g and 341.30 μg to 809.22 μg per plant, respectively. The NH₄⁺–N significantly reduced the Cd contents of different parts but enhanced the translocation factors of Cd stem to root (TF S/R) and leaf to stem (TF L/S) by 34.29~78.57% and 45.10~72.55%, respectively. The peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) enzyme activities of the kenaf increased with the N treatments, especially with NH₄⁺–N. Overall, applying low concentrations of NO₃⁻–N can better promote the extraction of Cd by kenaf.