ABSTRACT
Japanese fir (Abies firma Sieb. et Zucc.) usually shows a trifurcated branching form, differentiated into main and lateral shoots. We compared the radiocesium (137Cs) concentration in needles between the terminal main shoot and two terminal lateral shoots of Japanese fir in order to examine whether the shoot position (main or lateral) affected 137Cs concentration in needles. The 137Cs in needles of main shoot was significantly higher than that of the two lateral shoots, suggesting that differences in shoot positions are a factor affecting the 137Cs in needles. To examine the relationships between 137Cs in needles and shoot morphological traits, the dry mass of needles and branches and the length of branches were measured. The main shoots had statistically significant heavier needles and branches and longer branches than lateral shoots. However, the 137Cs in needles was not significantly correlated with the morphological traits of shoots. Our results suggest that the difference in 137Cs in needles between main and lateral shoots cannot be attributed to the difference in shoot morphology (dry weight and branch length). We recommend that when sampling needles for the evaluation of contamination of 137Cs, the shoot positions should be considered to eliminate 137Cs variation arising from these traits.
Acknowledgments
We thank Prof. K. Shizuma at the Graduate School of Engineering, Hiroshima University for his support in sample measurements and data analysis. The present research was supported through the Hiroshima University Phoenix Leader Education Program for the “Renaissance from Radiation Disaster”, funded by the Ministry of Education, Culture, Sports, Science and Technology.
Disclosure statement
No potential conflict of interest was reported by the authors.