Italian Ryegrass (IRG), which is known as high yielding and the highest quality winter annual forage crop, is grown in mid-south area in Korea. This study aims to analyze the cause-and-effect relationship between IRG yield and climate variables such as temperature and precipitation by using IRG data and climate data of Korea Weather Bureau. From path analysis of structural equation model under multivariate normality, we found that there was a weather effect on IRG yield that the winter grass IRG yield was directly affected by spring temperature and indirectly affected by spring rainfall. These results showed that IRG can be sown in early spring in the area where it is hard to prepare for winter due to low temperature. This paper can contribute to increase IRG yield by showing the cause-and-effect relationship and this study can be extended to various structural equation models for other crops.

The purpose of this research is to identify the significance of climate factors related to the significance of change of dry matter yield (DMY) of whole crop maize (WCM) by year through the exploratory data analysis. The data (124 varieties; n=993 in 7 provinces) was prepared after deletion and modification of the insufficient and repetitive data from the results (124 varieties; n=1027 in 7 provinces) of import adaptation experiment done by National Agricultural Cooperation Federation. WCM was classified into early-maturity (25 varieties, n=200), mid-maturity (40 varieties, n=409), late-maturity (27 varieties, n=234) and others (32 varieties, n=150) based on relative maturity and days to silking. For determining climate factors, 6 weather variables were generated using weather data. For detecting DMY and climate factors, SPSS21.0 was used for operating descriptive statistics and Shapiro-Wilk test. Mean DMY by year was classified into upper and lower groups, and a statistically significant difference in DMY was found between two groups (p<0.05). To find the reasons of significant difference between two groups, after statistics analysis of the climate variables, it was found that Seeding-Harvesting Accumulated Growing Degree Days (SHAGDD), Seeding-Harvesting Precipitation (SHP) and Seeding-Harvesting Hour of sunshine (SHH) were significantly different between two groups (p<0.05), whereas Seeding-Harvesting number of Days with Precipitation (SHDP) had no significant effects on DMY (p>0.05). These results indicate that the SHAGDD, SHP and SHH are related to DMY of WCM, but the comparison of R 2 among three variables (SHAGDD, SHP and SHH) couldn't be obtained which is needed to be done by regression analysis as well as the prediction model of DMY in the future study.

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Polycyclic aromatic hydrocarbons (PAHs) are a group of ubiquitous hazardous pollutants derived from fossil fuel, various combustion sources and pyrolysis of a wide range of plastics. Because PAHs can be uptake into crop plants, the inhibitory effects on rice and soybean plants were examined in greenhouse and growth chamber experiment. Soil-applied PAHs (phenanthrene of 0, 10, 30, 100 ppm) slightly reduced the plant height and dry weight both in transplanted rice and soybean plant. The inhibitory effect on growth was greater in soybean than rice. Plant height of soybean plants treated by 100 ppm was 58.9 cm and this value was 87.2% of untreated plant. In rice plant, the plant height was less inhibited (96.0% of untreated plant) by 100 ppm at 80 days after treatment (DAT). However, leaf chlorophyll content and chlorophyll fluorescence were less inhibited by PAHs at late growth stage (after heading) although the photosynthesis-related parameters were slightly inhibited from 20 DAT to 70 DAT. In agar medium experiment with infant seedlings, inhibition of seedling length and fresh weight by phenanthrene at 100 ppm were greater as compared to the experiment with adult plant in pot. Seedling length and fresh weight were reduced by 54.2% and 33.3% for rice and 27.9% and 13.2% for soybean, respectively. The results reflected that PAHs were more inhibitory during juvenile stage than adult stage and more inhibitory to rice plant than soybean for juvenile stage. et al., 1996)되어 있다. PAHs는 호 기적 조건에서 생분해가 된다고 한다 (Freitag et al., 1985;Srivastava et al. 1990,;Wild et al., 1990). 한편 식물은 근 권의 작용 등으로 인하여 PAHs의 분해가 촉진되는 경우가 있어 PAHs와 식물 생육 간에 밀접한 관계가 있는 것으로 ISSN 0252-9777(Print) ISSN 2287-8432(Online)