Light is a major external environmental factor that influences the circadian rhythm of photosynthetic organisms and various physiological phenomena, such as growth, maturation, and behavior. The number of light-reaching organisms changes depending on the season and atmospheric conditions, and the intensity and wavelength of light differ depending on the organisms inhabiting the environment. Altered light changes the circadian rhythm of fish, which is controlled by clock genes, such as period 2 (Per2), cryptochrome 1 (Cry1), and melatonin. In this study, we set the zeitgeber time (ZT; 14 light-10 dark, LD) based on the actual sunrise and sunset times and examined Per2 and Cry1 activities, levels of aralkylamine N-acetyltransferase (AANAT), and melatonin in Pholis nebulosa, a drifting seaweed species exposed to irregular light. Per2 and Cry1 levels increased during the daytime and decreased after sunset. The AANAT levels decreased during the daytime and increased during the night. Melatonin concentration was highest around midnight (ZT21, 23:30), but exhibited similar concentrations during the daytime. While the activity of Per2, Cry1, and AANAT levels exhibited a typical circadian rhythm observed in most vertebrates, melatonin concentrations did not show a significant difference between the daytime and nighttime. These findings provide insights into the circadian rhythm patterns of organisms exposed to irregular light environments, such as P. nebulosa, which differ from those of typical fish species.

본 연구는 우수한 꿀벌 신품종 육성을 위해 국립농업과학원에서 육성된 재래꿀벌 RX계통을 분양받아 ’23~’24 년까지 부안군 변산면에 위치한 전북농업기술원 잠사곤충시험장 양봉사에서 꿀벌세력, 수밀력, 질병저항성, 온순성, 질병발생, 월동능력을 한라벌 품종과 비교하여 조사하였다. 8~11월 RX계통의 꿀벌세력 감소는 3.9%로 한라벌 39.8% 대비 상대적으로 낮았고, 수밀력, 청소능력, 온순성은 유의적 차이가 없었다. 낭충봉아부패병 등 질병은 전북동물위생시험소에서 병성검정한 결과, 두 시험군 모두 항원이 검출되었으나 임상증상은 없었다. 그리고 월동 중 한라벌 품종은 폐사한 반면, RX계통은 모든 시험군이 월동에 성공하였고, 또한 월동전·후 먹이감 소량이 적어 월동능력이 우수한 것으로 판단하였다. 본 연구는 국립농업과학원 공동연구사업(PJ01504205)의 지원을 받아 수행하였다.

The Republic of Korea has implemented an obligatory vaccination on major livestock breeds to prevent and eradicate nationwide foot and mouth disease (FMD) since the end of 2010. The government has executed massive serological survey to check the immune level of various herds after vaccination, and seropositive rates against FMD virus (FMDV) structural proteins can be measured to assess FMD immunity level. The purpose of this study is to investigate the FMDV serological level of every cattle breeding farm in the country and to determine whether there is a significant difference between groups classified by time, age, and management authority. A total of 5,781 serum samples was collected in 18 cattle breeding farms from 2020 to 2021, and the seropositive rates were measured using PrioCHECK FMDV Type O ELISA kit. Firstly, the cattle breeding farms were classified by which they are managed: the central government, the local government, and the private agency. Every management authority had a seropositive rate of 99.5% or higher. Secondly, the samples were divided into 6 to 12 months old, 12 to 24 months old, and 24 months or more. The 6 to 12 months old group in 2020 showed a significantly low seropositive rate of 98.1%, but it was improved by implementing the enhanced vaccination policy from 2021 to 100%. In summary, there are considerably high seropositive rates including all groups with time, age, and by which they are managed, which means the FMD vaccination in cattle breeding farms is well-managed.

The objective of this experiment was to investigate the effect of drip irrigation volume on tomatoes (Solanum lycopersicum L.) grown in a greenhouse using perlite medium. Plants were treated by three different irrigation treatment I0, I25, and I50 (where irrigation volume of I25 and I50 was 25% and 50% higher than I0, having limited or no leaching). Growth characteristics of plants, yield and water use efficiency were measured. The result showed that plant height, leaf length and leaf width were lowest in the I0 treated plants. However, these parameters were not statistically significant differences between the plants that were grown in the I25 and I50 treatment. Soluble solids content, acidity and dry matter of 111th, 132nd, and 143rd days harvested tomato were higher in the plants irrigated with lowest volume (I0) than the higher volume (I25 or I50). In addition, water content was lower in the 111th and 132nd days of harvested tomatoes from the I0 treatment. The number of big-size tomatoes (>180 g) was significantly higher in the I25 irrigated plants. There was no significant difference in the total number of harvested fruits among the treatments. The average fruit weight and total yield of harvested tomatoes were lowest in the I0 treated plants. The water consumption of tomato was not significantly different amongst the treatments but water use efficiency was lowest in the I0 treatment. Principal component analysis revealed that total soluble solid and acidity of tomato showed a positive correlation between each other. These results suggest that I25 was the optimum irrigation treatment for tomato based on its measured growth characteristics, yield and water use efficiency.