Jin-Hyo Kim

Neonicotinoids are a group of systemic insecticides that are used extensively in agriculture, accounting for approximately 25% of the global market. The efficacy and systemic action of these compounds make them effective agents that bind to insect nicotinic acetylcholine receptors (nAChRs). In particular, nitroguanidines had a dominant market share of approximately 86%, driven by insecticide activity in Asia and the Americas. However, the extensive utilization and contamination of these substances pose a significant threat to pollinators, aquatic invertebrates, birds, and mammals. These concerns have prompted significant regulatory actions, including the EU’s prohibition on the outdoor use of imidacloprid, clothianidin, and thiamethoxam; the extension of restrictions in France; and the phase-out of thiamethoxam and clothianidin in Canada, while their use persists at considerable levels in Asia and the Americas. In addition, synergistic toxicity is an emerging concern with Neonicotinoids and other pesticide groups. Therefore, robust monitoring of environmental media and development alternatives is required to effectively manage ecological safety. Such measures are necessary to ensure the security of food production whilst safeguarding human and ecosystem health.

This study investigates the effect of nutrient composition and barley cultivars on saponarin production in young barley leaves (YBL) under low-intensity white LED light. Various treatments involving K ₂ HPO ₄ , NaCl, and salicylic acid (SA) were evaluated to be under 6500 K light with 210 PPFD. Among different nutrient combinations, 600 mg L ^-1 K ₂ HPO ₄ with 0.1% NaCl significantly enhanced saponarin concentration (12.3 g kg _dw ^-1 ) and total saponarin amount per plant (150 µg plant ^-1 ). In addition, the effects of light intensity on saponarin production were also examined across six barley cultivars, and the high light intensity (500 PPFD) notably increased total saponarin amount (212 µg plant ^-1 ) in Keunal-bori than Hyenuri cultivars. Otherwise, Hyenuri cultivar showed the highest total saponarin amount (114 µg plant ^-1 ) at low light intensity (100 PPFD), as well as the highest electricity efficiency (201 mg kWh ^-1 ). These findings provide valuable insights into optimizing cultivation conditions for each cultivar in plant factories to maximize saponarin production while balancing energy consumption and metabolic efficiency.

This study investigated the potential of feed additives for very long-chain fatty acids (VLCFA) and α-linolenic acid (ALA), which were identified in sea staghorn ( Codium fragile ) as natural feed additives to reduce enteric methane emissions in ruminants. An in vitro rumen fermentation model was used to evaluate the synergistic effects of VLCFAs and ALA, both individually and in combination, on methane​ emissions, dry matter digestibility, and the microbial community in the rumen. The results demonstrated that treatments with VLCFAs or ALA alone, at concentrations of up to 1.5% of the feed, did not significantly affect methane​ production, and significantly reduced the digestibility in the VLCFAs treatment. However, a mixture of 1.0% VLCFAs and ALA, particularly at a 2:1 ratio, significantly reduced methane​ emissions by 21% without compromising dry matter digestibility synergistically. Methanobrevibacter was over 96% of the total archaeal population, and Methanosphaera accounted for 2–3% of the total archaea. Furthermore, Prevotella and Succinivibrio were identified as predominant bacteria in the bacterial community. The treatment of VLCFAs or ALA alone slightly decreased the total gene counts, while the mixture of VLCFA-ALA treatment increased the total gene counts. In addition, the VLCFA-ALA mixture treatment increased the overall archaeal population and the archaea-to-bacteria ratio, while preserving the total bacterial population and digestibility; these were both negatively affected by VLCFAs alone.

The soil-applied pesticide can transfer to cultivated crops, and the residue concentration in the crops is decreased time-dependently by biological decomposition and crop growth. Pencycuron was most popularly used as a fungicide in field soil; however, the residue dissipation in greenhouse soil and its bioconcentration factor (BCF) for spinach, one of the most popular leafy vegetables, were not investigated. To estimate the residue dissipation of the soil-applied pencycuron, the residue dissipation was monitored in the recommended dose and the double dose treatments, and the 50% dissipation times ranged from 50 to 54 days; these times were met by the spinach cultivation time from seedling to harvest. The pencycuron residues in the spinach at the recommended dose and the double dose treatments were 0.006 mg kg⁻¹ and 0.025 mg kg⁻¹ at 48 days after the treatment (DAT), and 0.003 mg kg⁻¹ and 0.008 mg kg⁻¹ at 55 DAT, respectively. From the experimental data, the estimated BCFs of pencycuron were 0.003–0.008 for the spinach at 48 DAT and 0.001–0.002 at 55 DAT. During the seven-day additional cultivation, the fresh weights of the spinach were increased 1.5–1.8 times; thus, the crop growth would be considered as a main factor for the estimation of the crop residue.

The characterization of hexaconazole residues was evaluated through both single and sequential applications in Chinese cabbage and spring scallion. Maximum residue levels following foliar application were determined to be 1.14 mg kg^− 1 in the cabbage and 0.04 mg kg^− 1 in the scallion, whereas the soil application contributed minimally. Notably, the initial residue in the cabbage was 28 times greater than that observed in the scallion. Fourteen days after the final foliar application, the cabbage exhibited a 3.6-fold increase in fresh weight, compared to a 1.4-fold increase in the scallion. The degradation rates of hexaconazole were calculated at 0.089 day^− 1 for the cabbage and 0.207 day^− 1 for the scallion, corresponding with degradation half-lives (T_1/2) of 7.8 days for the cabbage, which was more than double the 3.4 days for the scallion. Biological T_1/2s in vitro were 210 min for the scallion, while the degradation was not detected in the cabbage. Finally, the 50% dissipation times (DT₅₀) were 3.6–3.8 days for the cabbage and 2.0-3.7 days for the scallion after foliar and sequential applications. In addition, hexaconazole exhibited persistence in soil under greenhouse conditions, resulting in the translocation of residues to rotational crops with detected concentrations reaching up to 0.013 mg kg^− 1.