## 3 Results
### Inhibitory Effects of Different Extracts of Arachis pintoi on the Growth of the Tested Plants  
Figure 1 presents the inhibitory effects of extracts with different polarity solvents including methanol, hexane, and ethyl acetate (EtOAc). It was exhibited that all extracts disclosed some reduction in germination and shoot and root lengths of noxious _E. crus-galli_ weed and _L. sativa_. Generally, the strength of the inhibitory effect was proportional to the dose. We then compared the inhibitory effects among the different solvent extracts by applying IC\({}_{50}\) values. These imply the extract quality that is required to reduce 50% of the shoot and root growth of _E. crus-galli_ and _L. sativa_. Therefore, a lower IC\({}_{50}\) value denotes a higher herbicidal activity. Among the extracted solvents, ethyl acetate extract (EtOAc) exhibited the greatest inhibition on germination of _E. crus-galli_ (IC\({}_{50}\) = 8.82 mg/mL), followed by methanol extract (IC\({}_{50}\) = 9.71 mg/mL), and hexane extract (IC\({}_{50}\) = 11.71 mg/mL). Conversely, hexane extract showed the highest suppression against the root and shoot length of _E. crus-galli_ (IC\({}_{50}\) = 4.08 and 8.40 mg/mL, respectively); the next most effective was EtOAc extract (IC\({}_{50}\) = 7.94 and 12.55 mg/mL, respectively), and methanol was the least (Figure 1). For germination suppression of _L. sativa_, hexane extract showed the highest inhibitory effect (IC\({}_{50}\) = 1.86 mg/mL), followed by methanol (IC\({}_{50}\) = 3.98 mg/mL), and the lowest was the EtOAc extract (IC\({}_{50}\) = 4.14 mg/mL). Also, the hexane extract displayed the strongest inhibition on the elongation of root and shoot of _L. sativa_ (IC\({}_{50}\) = 1.70 and 1.54 mg/mL, respectively), followed by the EtOAc extract (IC\({}_{50}\) = 2.01 and 2.03 mg/mL, respectively). Consequently, the suppressive strength can be ranked in the following order: hexane extract > EtOAc extract > methanol extract. In short, all extracts exerted strong inhibition; however, among the solvent extracts, hexane showed the most inhibition on the growth of the tested plants (Figure 1). \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Treatment** **(g/m2)**} & \multicolumn{2}{c}{**Inhibition (\%) Compared with the Control**} \\ \cline{2-3}  & **Dry Weight** & **Rice Yield** \\  & **(g)** & **(g/m2)** \\ \hline
200 & 13.71 c \(\pm\) 2.0 (43.1) & 520.4 a \(\pm\) 15.3 (\(-\)35.1) \\
150 & 15.86 bc \(\pm\) 2.21 (34.2) & 487.1 ab \(\pm\) 22.9 (\(-\)26.5) \\
100 & 18.82 bc \(\pm\) 1.33 (21.9) & 459.0 b \(\pm\) 18.3 (\(-\)19.2) \\
50 & 20.06 ab \(\pm\) 3.55 (14.5) & 396.6 c \(\pm\) 10.0 (\(-\)3.00) \\ Hand-weeding & 2.33 d \(\pm\) 0.49 (90.3) & 462.7 b \(\pm\) 11.2 (\(-\)20.2) \\ Herbicide & 2.13 d \(\pm\) 0.61 (91.2) & 488.5 ab \(\pm\) 23.6 (\(-\)26.9) \\ Control & 24.09 a \(\pm\) 3.20 (0.0) & 385.1 c \(\pm\) 13.1 (0.0) \\ \hline \hline \end{tabular} The means in the same column with different letters are significantly different at \(p\) \(<\) 0.05. The values in the parentheses are the inhibition means percentage compared with the control. The symbol “\(-\)” indicated the stimulation percentage compared to the control. The symbol “\(\pm\)” implies the standard error of the experiment.  
\end{table} 
Table 4: Allelopathic effects of _Arachis pintoi_ powder on the growth of natural paddy weeds and rice yield in field trial. Figure 1: Inhibitory effects of _Arachis pintoi_ extracts on the growth of _Echinochla crus-galli_ and _L. _L. _L. sativa_. Different letters (a, b, c) enclosed with columns within a parameter (germination, root, and shoot) are significantly different (_p_ \(<\) 0.05). Determination of Total Phenolic and Flavonoid Contents of the Different Extracts from Arachis pintoi  
In this experiment, we evaluated the total phenolic (TPC) and flavonoid (TFC) contents in three different extract phases from _A. pintoi_ powders (methanol, hexane, and ethyl acetate extracts).