Photocount statistics of ultra-weak photon emission from germinating mung bean.

Ultra-weak photon emission (UPE) is an endogenous bioluminescence phenomenon present in all biological samples with an active oxidative metabolism, even without an external pre-illumination. To verify the potential of UPE for non-invasive monitoring of metabolism and growth in germinating plants, the aim of this study was to investigate the UPE from a model system - germinating mung bean seedlings (Vigna radiata) - and analyze the statistical properties of UPE during the growth in two different conditions of imbibition (pure water and 1% sucrose). We found that in all days and in both conditions, photocount distributions of UPE time series follow the negative binomial distribution whose parameters changed during the growth due to the increasing ratio of signal-to-detector dark count. Correspondingly for both groups, the mean values of UPE increased during the seedlings growth, while the values of Fano factor show a decreasing trend towards 1 during the 6day period. While our results do not show any significant difference in hypocotyl length and weight gain between the two groups of mung seedlings, there is an indication of a tiny suppressing effect of sucrose on UPE intensity. We believe that UPE can be exploited for a sensitive non-invasive analysis of oxidative metabolism during the plant development and growth with potential applications in agricultural research.