This study evaluated cold tolerance and selected superior individuals from 100 Zoysia japonica ‘Zenith’ plants. Following pre-cold treatment at 4 °C for 24 h, candidates were screened using electrolyte leakage (EL) with a 10% selection intensity. Selected candidates and cold-sensitive controls were exposed to 0, −5, and −10 °C for 24 h and assessed using visual injury, EL, Evans blue staining, and 3,3′-diaminobenzidine (DAB) staining. Visual injury increased with decreasing temperature but did not clearly distinguish cold tolerance. Individual 11 exhibited the lowest lethal temperature causing 50% injury (LT₅₀) based on both EL (−10.4 °C) and Evans blue staining (−11.0 °C). The two LT₅₀ estimates were strongly correlated (r = 0.996) and concordant (Lin’s concordance correlation coefficient = 0.909). DAB-based recovery analysis showed effective hydrogen peroxide (H₂O₂) clearance in individuals 5, 11, 21, 23, and 40, with individual 23 exhibiting the lowest reactive oxygen species area under the curve (121.5). A modified Generalized Value Index integrating visual injury, mean LT₅₀, oxidative stress, and recovery slope identified individuals 5, 11, 18, 23, and 30 as superior cold-tolerant selections. Therefore, combining membrane-damage and oxidative-recovery indicators can provide a robust framework for selecting cold-tolerant Z. japonica ‘Zenith’ for field validation and breeding.

Moss in container seedling nurseries competes with seedlings for water and nutrients while blocking light, thereby inhibiting growth. This study aimed to address this issue by evaluating the moss control efficacy of 11 chemical compounds, including terpinyl acetate (TA), limonene, and Hinoki essential oil (HEO). The plate experiment results led to the selection of 6 substances (TA, limonene, HEO, pine leaf extract, baking soda, pelargonic acid) that stably controlled both Polytrichum commune Hedw. and Marchantia. Polymorpha L. When TA, limonene, and HEO were combined with surfactants, moss control rates increased and showed stable performance. In the container seedling experiment, TA, limonene, and HEO demonstrated high moss control effects while exhibiting low growth inhibition. When these three substances were combined with surfactants, the electrolyte leakage index (ELI) decreased, indicating minimal cell membrane damage. Additionally, TA treatment maintained stable soil physicochemical properties with no significant changes in pH or nutrient levels. Microscopic analysis of moss cells showed cell wall deformation and expansion of intercellular spaces in the three substance treatment groups. Future verification of long-term effectiveness, expansion of application targets, and assessment of economic feasibility could lead to the development of eco-friendly moss removal agents for improving container seedling quality.

Cold stress is a critical factor restricting the cultivation of subtropical evergreen species such as Camellia sinensis and C. japonica in temperate climates. This study aimed to develop an integrated framework for evaluating cold tolerance by combining visual assessment, electrolyte leakage (EL), Evans blue staining, and nonlinear regression modeling. All experiments were conducted with n = 3 samples per treatment, and statistical analyses were performed at a significance level of α = 0.05. Under freezing treatment at −6 °C, C. japonica exhibited faster and more severe damage, including leaf curling and vein darkening, compared to C. sinensis. Electrolyte leakage and cell death increased rapidly in C. japonica, and a sharp rise in cell death occurred in both species when EL exceeded 55%. Logistic regression of EL data estimated LT₅₀ values of −10.96 °C for C. sinensis and −9.38 °C for C. japonica, while EL Temp₅₀ values were −9.59 °C and −8.97 °C, respectively, indicating higher membrane stability in C. sinensis. The difference in LT₅₀ between the two species was statistically significant (p < 0.05). Biochemical and heatmap analyses from 25 °C to −12 °C showed that C. sinensis maintained higher chlorophyll, antioxidant activity, and sugar levels, reflecting stronger cold tolerance. In contrast, C. japonica accumulated more proline and MDA, indicating higher stress sensitivity and membrane damage. This study presents a reproducible, quantitative framework for evaluating cold tolerance in Camellia species, offering valuable insights for breeding and expanding cultivation under climate change.