Topping is an essential step in cotton cultivation in Xinjiang, China, which can effectively increase the number of bolls per plant and optimize the yield and quality. Paclobutrazol, as a common chemical topping agent for cotton, faces challenges such as unstable topping effect and limited leaf surface absorption during application. In this study, paclobutrazol was used as the ligand and a zinc complex was synthesized by the thermosolvent method to replace paclobutrazol and improve the topping effect on cotton. The structure of the complex was characterized using FTIR, UV-vis, TG, and XRD analyses. The results confirmed that each zinc ion coordinated with four nitrogen atoms from the triazole rings of paclobutrazol and two oxygen atoms from nitrate ions, forming an octahedral geometry. Surface tension measurement and analysis revealed that the complex had a surface tension reduction of 12.75 mN/m compared to paclobutrazol, thereby enhancing the surface activity of the complex in water systems and improving its absorption efficiency on plant leaves. Two-year field trials indicated that the foliar application of the complex at a dosage of 120 g·hm⁻² in inhibiting cotton plant height was more stable to that of paclobutrazol or mepiquat chloride. It also shortened the length of fruiting branches, making the shape of cotton plants compact, thereby indirectly improving the ventilation and light penetration of the cotton field and the convenience of mechanical harvesting. Yield data showed that, compared with artificial topping, the complex at a dosage of 120 g·hm⁻² treatment increased cotton yield by approximately 4.6%. Therefore, the paclobutrazol–zinc complex is a promising alternative to manual topping and have great application potential in future mechanized cotton production.

Kasugamycin (KSM) is easily affected by photolysis, acid–base destruction, and oxidative decomposition in the natural environment, leading to its poor durability and low effective utilization rate, which affects its control effect on plant bacterial diseases. Nanomaterials modified with environment-responsive agents enable the control of the release of pesticides through intelligently responding to external stimuli, thereby improving efficacy and reducing environmental impact. In this study, a pH-responsive controlled release system was constructed using zeolitic imidazolate frameworks (ZIF-93) for the sustained and targeted delivery of KSM. The synthesized KSM@ZIF-93 exhibited a diameter of 63.93 ± 11.19 nm with a drug loading capacity of 20.0%. Under acidic conditions mimicking bacterial infection sites, the Schiff base bonds and coordination bonds in ZIF-93 dissociated, triggering the simultaneous release of KSM and Zn²⁺, achieving a synergistic antibacterial effect. Light stability experiments revealed a 34.81% reduction in UV-induced degradation of KSM when encapsulated in ZIF-93. In vitro antimicrobial assays demonstrated that KSM@ZIF-93 completely inhibited Erwinia amylovora at 200 mg/L and had better antibacterial activity and persistence than KSM and ZIF-93. The field experiment and safety evaluation showed that the control effect of KSM@ZIF-93 on pear fire blight at the concentration of 200 mg/L was (75.19 ± 3.63)% and had no toxic effect on pollen germination. This pH-responsive system not only enhances the stability and bioavailability of KSM but also provides a targeted and environmentally compatible strategy for managing bacterial infections during the flowering period of pear trees.