## 3 Results and Discussion
### OAV Analysis of HS-SPME-GC-MS Data  
The contribution of VOCs to the overall aroma profile of tea is influenced not only by their concentrations but also by their respective odor thresholds. The ratio between an odor-ant's concentration and its detection threshold, commonly referred to as the odor activity value (OAV), serves as a critical determinant of its impact on the sample's aroma [4; 26; 28]. Comprehensive details regarding the concentration, odor threshold, odor descriptions, and OAVs of VOCs across the four sample groups are presented in Table S4. VOCs with OAVs \(\geq\)1, as well as those with OAVs between 0.1 and 1, are selectively highlighted and discussed in Table 1. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \multirow{2}{*}{**NO.**} & \multirow{2}{*}{**Volatile Compounds**} & \multirow{2}{*}{**Odor Characteristics**} & \multirow{2}{*}{**OT** (\#g/L)**} & \multicolumn{5}{c}{**OAVs**} \\ \cline{4-9}  & & & **FD-CK** & & **FD-D** & **WNZ-CK** & **WNZ-D** \\ \hline
1 & Hex-(3Z)-enyl acetate & Green, fruity & 13 & 0.19 & - & 1.58 & 0.25 \\ \hline
2 & Methyl salicate & Minty, green & 40 & 0.12 & 0.17 & 0.27 & 1.18 \\ \hline
3 & 1-Hexanol & Herbal, fruity & 5.6 & 0.62 & 0.63 & 0.64 & 0.64 \\ \hline
4 & 1-Heptanol & Green, leafy, violet & 5.4 & 0.68 & 0.79 & 0.7 & 0.7 \\ \hline
5 & 1-Octen-3-ol & Earthy, mushroom & 1.5 & 2.36 & 2.53 & 2.35 & 2.76 \\ \hline
6 & (Z)-Hex-3-en-1-ol & Green, grassy & 3.9 & 1.66 & - & - & - \\ \hline
7 & 1-Octanol & Waxy, green, orange & 125.8 & 0.03 & 0.06 & 0.1 & - \\ \hline
8 & 1-Linalool & Floral, citrus, rose & 0.22 & 3155.46 & 1577.42 & 2307.87 & 2190.92 \\ \hline
9 & 1-Nonanol & Floral, rose, orange & 45.5 & - & - & 0.16 & - \\ \hline
10 & 1-Octen-3-ol & Farlow, mushroom & 1.1 & 119.45 & 115.99 & 130.9 & 99.64 \\ \hline
11 & 6-methyl-5-Hepten-2-one & Citrus, lemon & 0.16 & - & 1.68 & - & 3.06 \\ \hline
12 & 1-Octen-3-one & Earthy, herbal, mushroom & 0.003 & - & - & - & 113.76 \\ \hline
13 & (Z)-Jasmone & Floral, woody, herbal & 0.26 & 9.31 & 0.16 & - & 1.81 \\ \hline
14 & (E)-alpha-Ionone & Violet & 0.1 & - & 5.09 & 2.76 & 29.44 \\ \hline
15 & beta-Damascone & Fruity, floral, berry & 0.002 & 9.32 & 19.18 & 60.44 & 157.58 \\ \hline
16 & (E)-beta-Ionone & Foral, fruity, woody & 0.007 & 217.88 & 8.6 & 746.08 & 658.21 \\ \hline
17 & Hexanal & Green, grassy & 5 & 0.61 & 1.34 & 0.81 & 1.24 \\ \hline
18 & 2-Hexenal & Green, almond, fruity & 30 & 0.16 & 0.66 & 0.14 & 0.67 \\ \hline
19 & Heptanal & Green, fatty, herbal & 2.8 & 0.71 & 0.7 & - & 0.68 \\ \hline
20 & (E)-2-Heptenal & Green, vegetable, fatty & 13 & - & 0.14 & - & 0.16 \\ \hline
21 & (E,E)-2,4-Heptadien & Fatty, green & 0.032 & - & 58.5 & - & 59.41 \\ \hline
22 & Octanal & Aldehydic, citrus & 0.587 & 4.02 & 4.45 & - & 4.13 \\ \hline
23 & Oct-(2E)-enal & Fatty, green, herbal & 0.2 & - & - & - & 9.83 \\ \hline
24 & Benzeneacetaldehyde & Green, floral, hyacinth & 5.2 & - & 0.19 & - & 0.2 \\ \hline
25 & Nonanal & Aldehydic, orange, rose & 1.1 & 2.79 & 3.18 & 2.78 & - \\ \hline
26 & (E)-2-Nonenal & Fatty, cucumber, citrus & 0.19 & 10.01 & - & - & 10.78 \\ \hline
27 & Decanal & Aldehydic & 3 & 0.74 & 0.96 & 0.71 & 0.91 \\ \hline
28 & (E)-2-Decenal & Fatty, earthy, green & 0.3 & 7.9 & 7.82 & 7.48 & 10.78 \\ \hline
29 & Nona-(2E,4E)-dienal & Fatty, melon, green & 0.1 & - & - & - & 19.16 \\ \hline
30 & Neral & Citrus, lemon & 53 & 0.04 & 0.04 & 0.62 & - \\ \hline
31 & Citral & Citrus, lemon, sweet & 40 & 1.06 & 1.43 & 1.42 & 1.43 \\ \hline \end{tabular}
\end{table} 
Table 1: The main aroma-active compounds with an odor activity value (OAV) \(\geq\) 0.1 in 4 groups. In total, 45 VOCs exhibited OAVs \(\geq\)0.1, with 27 of these compounds showing OAVs greater than 1 across the four groups. Specifically, 15, 16, 14, and 22 VOCs with OAVs \(\geq\)1 were identified in FD-CK, FD-D, WNZ-CK, and WNZ-D, respectively. These findings suggest that drought stress prompted an increase in the number of VOCs with OAVs \(\geq\)1 in both cultivars, with WNZ-D experiencing a marked 57.14% rise compared to WNZ-CK.