## 4 Discussion
During the present study, the growth of unicellular _M. aeruginosa_ was inhibited more strongly by juglone than that of the colonial type (Figure 2e; Figure 4). We observed this same pattern of differential inhibitory effects on _M. aeruginosa_ in a prior study using different allelochemicals extracted from rice hulls [18]. Notably, juglone showed a selective effect on cyanobacteria, compared to its effects on green algae and some diatoms. These results indicate that juglone has potential as an effective bactericode for controlling blooms of nuisance cyanobacterial species while leaving other algae less affected. Considering that _M. aeruginosa_ generally exists in its colonial form, relatively high concentrations of juglone (>1 mg L\({}^{-1}\)) would be necessary for effective control. A combination of juglone and other allelochemicals [18; 21; 22] may allow juglone to be effective even at lower concentrations. The synergetic effects of such combination treatments could not only to improve inhibition, but also reduce the hormetic or stimulatory effects induced by one allelochemical. This hypothesis warrants further investigation. Our results support the general allebotathic hypothesis that biotic sensitivity to chemicals varies according to diverse parameters, such as taxonomy, morphology, and anatomy of target organisms, as well as types and doses of chemicals [48; 49]. The results of our laboratory and field assays demonstrate that algal sensitivity to juglone differed depending on algal taxa and cell types (Table 3). \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Classifications**} & \multirow{2}{*}{**Species**} & **Growth** & **Concentrations (mg L\({}^{-1}\)) and Effects** & **References** \\  & & **Resposes** & & \\ \hline \multirow{4}{*}{Diatoms} & Asf & H & 0.01(\(-\)), 0.1(\(+\)), 1(\(----\)) & Lab \\  & Frc & H & 0.01(\(-\)), 0.1(\(++\)), 1(\(----\)) & Lab \\  & Sth & A(\(-\)) & 0.01(\(-\)), 0.1(\(--\)), 1(\(--\)) & Lab \\  & Sya & H & 0.01(\(-\)), 0.1(\(-\)), 1(\(---\)) & Lab \\ \hline \multirow{4}{*}{Green algae} & Chv & A(\(+\)) & 0.01(\(++\)), 0.1(\(++\)) + + + + & Lab \\  & Cla & H & 1.74(\(+\)), 17.4(\(-\)), 174(\(----\)) & [25] \\  & Euc & H & 1.74(\(+\)), 17.4(\(-\)), 174(\(----\)) & [25] \\  & Mit & H & 1.74(\(+\)), 17.4(\(-\)), 174(\(----\)) & [25] \\  & Nes & A(\(-\)) & 0.52(\(---\)) & [27] \\  & Pam & A(\(-\)) & 1.74(\(-\)), 17.4(\(-\)), 174(\(----\)) & [25] \\  & Sca & H & 0.01(\(+\)), 0.1(\(+\)) 0.5(\(+\)), 1(\(---\)), 10(\(----\)) & [24] \\  & Sca & A(\(+\)) & 0.1(\(++++\)), 1(\(++\)) & Field \\  & Scq & A(\(+\)) & 0.01(\(++\)), 0.1(\(++\)), 1(\(++\)) & Lab \\  & Scq & A(\(+\)) & 0.1(\(++\)) + 1(\(++\)) & Field \\  & Sec & A(\(-\)) & 0.174(\(-\)), 17.4(\(--\)) & [26] \\  & Spg & H & 1.74(\(+\)), 17.4(\(-\)), 174(\(----\)) & [25] \\ \hline \multirow{4}{*}{Cyanobacteria} & Anf & H & 0.01(\(+\)), 0.1(\(-\)), 0.5(\(--\)), 1(\(---\)), 10(\(--\)) & [24] \\  & Anf & A(\(-\)) & 0.1(\(----\)), 1(\(---\)) & Field \\  & Ma ** & A(\(-\)) & 0.01(\(--\)), 0.1(\(--\)), 1(\(---\)) & Lab \\  & Ma ** & A(\(-\)) & 0.1(\(-\)), 1(\(-\)) & Field \\  & Noc & H & 0.01(\(+\)), 0.1(\(+\)), 0.5(\(-\)), 1(\(-\)), 10(\(--\)) & [24] \\  & Och & A(\(-\)) & 0.0174(\(-\)), 0.174(\(--\)) & [26] \\  & Ocu & A(\(-\)) & 0.1(\(-\)), 1(\(---\)) & Field \\  & Phs & A(\(-\)) & 0.1(\(---\)), 1(\(---\)) & Field \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparison of allebotatic responses of various freshwater algae to juglone. First, the inhibitory effect of juglone at 0.1 mg L\({}^{-1}\) was highest against the unicellular form of _Microystis_, followed by _Anabaena_, _Phormidium_, _Oscillatoria_, and _Microystis_ in its colonial form. Second, the cyanobacteria were the taxonomic group most sensitive to juglone, followed by diatoms (aside from _S. hantzschii_) and green algae. Finally, unicellular morphology was most sensitive to juglone, followed by small chain, large chain, and colonial morphologies.