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Strict biennials are among the least known lifecycles in plant ecology due to their rarity in nature, and their population genetics still remain unknown. The present study addressed the strict biennial lifecycle and associated population genetics of Pedicularis hallaisanensis , an endangered endemic plant in Korea. All P. hallaisanensis individuals were counted in August from 2021 to 2023 in the wild population of Gayasan National Park, and lifecycle and morphological changes were monitored monthly. A de novo draft genome and single nucleotide polymorphism (SNP) analysis were used to study the population's genetic structure. P. hallaisanensis strictly requires a 2-year lifecycle per generation, including 8 and 10 months of growing periods as a first-year seedling and second-year adult, respectively. Facultative annual and perennial lifecycles were undetected, resulting in odd-year and even-year flowering cohorts. Permutational multivariate analysis of variance on the detected 3,716 SNPs demonstrated that the flowering group (p < 0.005), microhabitat (p < 0.001), and their interaction (p < 0.01) had a significant effect on genetic structure, which was differentiated between odd-year and even-year flowering cohorts. Other cluster analyses also showed that a microhabitat under historical anthropogenic interventions contained lowered genetic diversity due to a decreased genetic distance between odd-year and even-year flowering cohorts (p < 0.05). Overall, the findings suggest that excessive anthropogenic interventions should be avoided to preserve genetic diversity in the wild P. hallaisanensis population. Moreover, conservation programs for similar biennial plants should collect wild breeds from both odd-year and even-year flowering cohorts to improve the genetic diversity of artificially propagated individuals. [ABSTRACT FROM AUTHOR]

Pedicularis hallaisanensis Hurusawa, native to Mt. Halla and Gaya, is an endangered endemic species. To support conservation efforts, this study investigated its germination characteristics and kind of seed dormancy. The seeds of P. hallaisanensis had fully developed linear embryos at dispersal, with no additional embryo growth observed. Water imbibition was observed prior to germination. The seeds were water-permeable. The seeds did not germinate at four temperature treatments (4 °C/1 °C, 15 °C/6 °C, 20 °C/10 °C, and 25 °C/15 °C). However, cold stratification and gibberellic acid treatments broke seed dormancy. Total germination was 15%, 15%, and 45% at 12, 16, and 20 weeks of cold stratification, respectively. Total germination at 25 °C /15 °C for GA treatments were 0%, 25%, 25%, and 80% at 500, 1000, 1500, and 2000 mg/L, respectively. This study showed that the seeds of P. hallaisanensis have intermediate physiological dormancy, requiring 20 weeks of cold stratification or more than 2000 mg/L GA concentration to maximize total germination. These results are useful for understanding ecophysiological mechanisms related to the species' habitat and for mass propagation to conserve this endangered species. [ABSTRACT FROM AUTHOR]

The orchid Dendrobium moniliforme faces endangerment due to habitat loss and illegal harvesting, necessitating the development of an optimized artificial propagation system to aid conservation and reintroduction efforts. This study evaluated the effects of three plant growth media, namely Murashige and Skoog (MS), Hyponex, and Orchid Maintenance Medium (OMM) (P668), and various organic additives (apple homogenate, banana homogenate, and coconut water) on the in vitro seedling growth of D. moniliforme. The results reveal that, in early postgermination stages, seedlings achieve maximum growth in the Hyponex medium, with a fresh weight (92 mg) and root length (2.7 cm) approximately 20-fold greater than those in the MS medium and OMM. After 6 months, for seedlings grown in MS medium and OMM with banana (50 g·L−1), the mean fresh weights were 29 and 107 mg, respectively; however, the highest biomass was observed in seedlings grown in the Hyponex medium with coconut water (50 mL·L−1), exhibiting a mean fresh weight of 201 mg. This study highlights Hyponex medium with coconut water as the most effective combination for promoting D. moniliforme growth and identifies suitable organic supplements for the in vitro cultivation of seedlings from asymbiotic seed culture. This propagation system offers valuable technical support for the mass production and conservation of this epiphytic orchid. [ABSTRACT FROM AUTHOR]

Atmospheric particles can impact cloud formation and play a critical role in regulating cloud properties. However, particle characteristics at the single-particle level and their ability to act as ice-nucleating particles (INPs) over the marine atmosphere are poorly understood. In this study, we present micro-spectroscopic characterizations and ice nucleation properties of particles collected during a cruise from South Korea to Antarctica in 2019. Most of the samples were dominated by fresh sea salt, aged sea salt, and sea salt mixed with sulfate particles, with total number percentages ranging from 48 % to 99 % over the western Pacific and the Southern Ocean. The mixing-state index of the particle population ranged from 50 % to 95 % over the Northern Hemisphere and Southern Hemisphere. Multiphase processes on sea salt particles resulted in chlorine deficiency. This selective aging process made the marine particle population more externally mixed. Ice nucleation onset conditions primarily for the deposition mode were measured and the investigated particles showed diverse ice nucleation abilities. The fresh sea salt particles with organic coatings exhibited the highest ice nucleation ability at a relative humidity with respect to ice as low as 121 %. The sea salt mixed sulfate particle was enriched in INPs by a factor of 1.9. Aging processes affected both the mixing state of the particles and their ice nucleation abilities. Our analysis shows that assuming an internally mixed particle population in the marine atmosphere can lead to errors of several orders of magnitude in predicting ice nucleation rates. [ABSTRACT FROM AUTHOR]

Black carbon (BC) aerosol is considered one of the most important contributors to rapid climate warming as well as snow and sea ice melting in the Arctic, yet the observations of BC aerosols in the Arctic Ocean have been limited due to infrastructural and logistical difficulties. We observed BC mass concentrations (mBC) using light absorption methods on board the icebreaker R/V Araon in the Arctic Ocean (< 80° N and 166° E to 156° W) as well as the North Pacific Ocean in summer and early autumn of 2016–2020. The levels, interannual variations, and pollution episodes of mBC in the Arctic were examined, and the emission sources responsible for the high-BC episodes were analyzed with global chemistry-transport-model simulations. The average mBC in the surface air over the Arctic Ocean (72–80° N) observed by the 2019 cruise exceeded 70 ng m -3 , which was substantially higher than that observed by cruises in other years (approximately 10 ng m -3). The much higher mBC observed in 2019 was perhaps due to more frequent wildfires occurring in the Arctic region than in other years. The model suggested that biomass burning contributed most to the observed BC by mass in the western Arctic Ocean and the marginal seas. For these 5 years, we identified 10 high-BC episodes north of 65° N, including one in 2018 that was associated with co-enhancements of CO and CH 4 but not CO 2 and O 3. The model analysis indicated that certain episodes were attributed to BC-containing air masses transported from boreal fire regions to the Arctic Ocean, with some transport occurring near the surface and others in the mid-troposphere. This study provides crucial datasets on BC mass concentrations and the mixing ratios of O 3 , CH 4 , CO, and CO 2 in the western Arctic Ocean regions, and it highlights the significant impact of boreal fires on the observed Arctic BC during the summer and early autumn months. [ABSTRACT FROM AUTHOR]