Background and aimsContinuous cropping obstacles (CCOs) are frequently encountered during the cultivation of Lagenaria siceraria (L. siceraria) in the same field for many years, which is related to the secondary metabolites secreted by plants, among which vanillin is one of the factors causing CCOs of L. siceraria. This study investigated the effects of different concentrations of exogenous brassinolide (BR) on L. siceraria under CCOs.MethodsHigh-performance liquid chromatography (HPLC) was used to determine the contents of vanillin in rhizosphere soil of non-planted soil, 1-year-old, 2-year-old, and 3-year-old L. siceraria cultivation. This study investigated the effects of BR at concentrations of 0.05, 0.10, 0.20 and 0.40 mg/mL on L. siceraria under CCOs by applying 6.00 mg/mL vanillin to simulate CCOs.ResultsThe contents of vanillin in the rhizosphere soil of non-planted soil, 1-year-old, 2-year-old, and 3-year-old were 0.01, 0.03, 0.06 and 0.10 mg/g. The BR could effectively alleviate the stress imposed by vanillin and enhance the tolerance of L. siceraria to vanillin stress. When the concentration of BR was 0.20 mg/mL, the alleviation effect on vanillin stress was the most significant. Compared with the vanillin stress group, the plant height, the projected area of the root, number of tips, and total root length enhanced by 1.52, 4.21, 4.43, and 6.12 times. When the light intensity was 1200 lx, the transpiration rate and stomatal conductance increased by 68.57% and 48.00%. At the same time, the antioxidant enzyme activities had the best alleviation at 0.20 mg/mL.ConclusionThe vanillin significantly inhibited the growth of L. siceraria seedlings at elevated concentrations. Furthermore, its persistent accumulation in the soil via root exudation was identified as a contributing factor to CCOs. It was worth noting that 0.20 mg/mL BR could alleviate the damage caused by CCOs to L. siceraria seedlings.

In this paper, pectin-based plastic films were developed by grafting vanillin to pectin chains and introducing Fe3+ ions. The mechanical properties, thermal stability, moisture resistance, UV-light barrier property, biodegrad-ability, and practical application of fabricated plastic film were evaluated. Results confirmed the successful grafting of vanillin and the presence of hydrogen bonds and metal-ligand bonds, giving the plastic film highest fracture stress of 41.68 +/- 4.10 MPa, which was nearly 481.31% enhancement than that of neat pectin film. Additionally, the thermal stability, moisture resistance, and UV-blocking property (200-400 nm) of fabricated plastic film were significantly improved. Moreover, the plastic film exhibited satisfying processability, which can be processed to bag and appearing excellent food preservation ability. After use, the plastic film can be completely biodegradable in soil (degradation time approximate to 7 weeks) and seawater without manual interference. Thus, our proposed pectin-based plastic film can be recommended as a non-polluting and sustainable food packaging substitute.