Relationship between seed coat characteristics and water uptake, electrical conductivity after soaking in soybean genotypes

The objective of the study was to assess the effect of different seed coat and seed size on the speed of water uptake and electrical conductivity due to cotyledon damage. Measurement of the time course of water uptake by four varieties of soybean revealed that varieties with black seed coat took up water more slowly than varieties with yellow seed coat. The varieties with black seed coat also showed the evidence of less imbibition injury as revealed by low electrical conductivity. The major factors contributing to slow water uptake in black seeds were fewer small, elongated seed coat pores, high density waxy material embedded in the seed coat(similar to hard seed) and thick palisade cell. It is likely that a closed micropyle was related with initial water uptake. On the other hand, although small seeds also have high density waxy material embedded in the seed coat, small seed varieties imbibed water faster than large. We thought that this result was due to the greater area of seed coat in touch with water, and seed coat ability in controlling the water potential of seed. But electrical conductivity after aging was higher in yellow seed than black seed regardless of seed size.