To study the effects of external ethanol pretreatment on growth and drought tolerance in alfalfa, 21-day-old plants were pretreated with ethanol at 0-1000 mM for 4 days and then subjected to drought stress for 9 days. Ethanol pretreatment significantly enhanced plant survival under drought conditions, with the highest survival rate observed in the 250 mM treatment. In contrast, fresh weight and dry weight were not significantly affected by ethanol pretreatment. Relative water content was increased 7.15% at 250 mM ethanol treatment compared to 0 mM ethanol treatment. Chlorophyll content decreased compared to the control, while carotenoid content remained unchanged. total soluble carbohydrate content was reduced by ethanol pretreatment. Hydrogen peroxide (H2O2) levels were maintained only in plants treated with 250 mM ethanol, whereas lower and higher concentrations resulted in significantly decreased H2O2 content. These results suggest that ethanol pretreatment does not affect alfalfa growth, but significantly improves survival rate under drought conditions by maintenance of relative water content. Furthermore, it suggests that chemical priming using ethanol pretreatment could be applied as a method to improve drought tolerance of alfalfa plants.

ABSTRACT
Ⅰ. INTRODUCTION
Ⅱ. MATERIALS AND METHODS
    1. Plant growth and ethanol treatment
    2. Measurement of relative water content
    3. Measurement of chlorophyll a, b and carotenoidcontent
    4. Measurement of total soluble carbohydrate content
    5. Measurement of hydrogen peroxide (H2O2)
    6. Statistical analysis
Ⅲ. RESULTS AND DISCUSSION
    1. Effects of ethanol pretreatment on growth of alfalfa plants
    2. Effects of ethanol pretreatment on relative watercontent (RWC)
    3. Changes in chlorophyll a, b and carotenoid content
    4. Changes in total soluble carbohydrate content
    5. Changes in hydrogen peroxide (H2O2) content
Ⅳ. CONCLUSIONS
Ⅴ. ACKNOWLEDGEMENTS
Ⅵ. REFERENCES

• Gi-Beom Nam(Division of Applied Life Science (BK21) and Institute of Agriculture & Life Science (IALS), Gyeongsang National University, Jinju 52828, Republic of Korea)
• Il-Kyu Yoon(Division of Applied Life Science (BK21) and Institute of Agriculture & Life Science (IALS), Gyeongsang National University, Jinju 52828, Republic of Korea)
• Byung-Hyun Lee(Division of Applied Life Science (BK21) and Institute of Agriculture & Life Science (IALS), Gyeongsang National University, Jinju 52828, Republic of Korea) Corresponding author