Changes of growth characteristics and free amino acid content of cultivated Porphyra yezoensis Ueda (Bangiales Rhodophyta) blades with the progression of the number of harvests in a nori farm.

It is essential for successful Porphyra breeding to understand the growth characteristics and the quantitative aspect of the taste of gametophytic blades. However, there have been only a few studies on such characteristics with the progression of the number of harvests in nori farms. In this study we examined the changes of blade shape, blade thickness and free amino acid (FAA) content of two P. yezoensis f. narawaensis pure lines (HG-4 and HG-5) with the progression of the number of harvests in a nori farm. With the progression of the number of harvests, the blade length-to-width ratio of both pure lines decreased, while the blade thickness increased. From the results, it is suggested that the increase of blade length is significantly higher in HG-4 than in HG-5, and that the blade is thicker in HG-5 than in HG-4. Total FAA contents between the two lines were not significantly different throughout the investigation period. Among the major four FAA (aspartic acid, glutamic acid, alanine and taurine), only glutamic acid content decreased with the progression of the number of harvests in both pure lines. These results suggest that the superior taste of dried nori sheets made of the first harvest of blades is due to thinner blades and higher content of glutamic acid. [ABSTRACT FROM AUTHOR]