Growth Characteristics and Physiological Responses of Soybean (Glycine max L.) under Excessive Soil Moisture Stress

초록

Due to global climate change and poor drainage soil characteristic in paddy fields, soybeans which are one ofmain upland crops in Korea are prone to get stressed by excessive soil moisture during cultivation. Excessivesoil moisture stress causes poor growth, yield loss, and disease to soybeans. In order to prevent damages byexcessive soil moisture stress, it is important to understand responses of soybeans under excessive soil moisturecondition. Therefore, this study investigated morphological and physiological responses of soybeans byexcessive soil moisture at various growth stages; V2, R1, R3, R5 and whole growing period. Soybeans wereplanted and characteristics of photosynthesis, chlorophyll fluorescence and 1-Aminocyclopropane-1-carboxilicacid (ACC) were measured from leaves after excessive soil moisture treatment. After harvest, growth and yieldcomponents were measured. As a result, soybean showed the smallest stalk height from soybeans which hadexcessive soil moisture at V2 and whole growing period. On the other hand, the greatest yield loss occurredwhen excessive soil moisture applied at R5, while the smallest at R2 and whole growing period. Soybean leavesshowed the smallest photosynthetic rate and stomatal conductance under excessive soil moisture condition. These decline continued at least 1 week and restored to the values of photosynthetic rate and stomatal conductancefrom soybeans with no stress. Soybeans under excessive soil moisture exhibited greater ACC values thanone of no stress. These increment of ACC continued 2 weeks and diminished. Soybeans treated with excessivesoil moisture at V2, R1, R3 and whole growing period had decrease in photosynthetic rate and increase in ACCvalues. These results can indicate that changes of ACC contents in soybean leaves may be used as indicator ofexcessive soil moisture stress.

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