Abstract: The production and turnover of fine root plays an important role in terrestrial C- and nutrients cycling of terrestrial ecosystem, and is of significance in indicating global environmental changes. Fine root longevity is a key parameter in estimating fine root turnover, which determines the velocities of C- and nutrients consuming and cycling. However, the estimated longevity of fine root had a larger difference, owing to the discrepancy among the methods adopted.As for the newest estimation methods minirhizotron and radiocarbon (e . g . , bomb ¹⁴C, and FACE ¹³C), there was a 10 times more difference of estimated value between them. This paper introduced the principles and advantages of these two methods, and analyzed the reasons inducing such a difference of estimation results from the aspects of fine root heterogeneity, mortality pattern, and sampling errors, which would benefit the future study in this field.

Key words: Oryza sativa, Allelopathy, Resources competition, Nitrogen stress, Econiche, Allelopathy-competition separation based bioassay (ACS)