## 3 Results
### NMR Monitoring of Mild Drought Stress
Figure 4: T\({}_{2}\) in ms of the first (**a**,**b**), second (**c**,**d**) and last peaks (**e**,**f**) obtained in leaves from two ranks and for all treatments at 42 days after sowing (DAS) (**a**,**c**,**e**) and 57 DAS (**b**,**d**,**f**). Bars represent standard deviation. Different letters means statistical differences (\(p<0.05\)). Figure 3: (**a**) T\({}_{2}\) distribution obtained by the MEM method for leaf ranks 8 and 4 of well-watered plants at the second stage; (**b**) correlation between amplitudes of the second and third peaks for LR 4 (red) and LR 8 (bleu) for stages 1 (cube) and 2 (triangle). The T\({}_{2}\) value of the first peak (T\({}_{2\text{-}1}\)) remained around 18 ms in the older leaves (LR 4) under all treatments at both stages. Likewise, the T\({}_{2\text{-}1}\) of leaf rank 8 remained around 15 ms at the two stages. Water stress had no effect on T\({}_{2\text{-}1}\) independently of the developmental stage of the plants. The addition of TIMAC SL28 increased T\({}_{2\text{-}1}\) at 57 DAS in old leaves (LR 4). The T\({}_{2\text{-}2}\) of the second peak measured in old leaves (LR 4) of the control plants remained around 160 ms at both stages (Figure 4c,d). At 42 DAS, T\({}_{2\text{-}2}\) decreased significantly (around 140 ms) in the leaves of water stressed plants, but at 57 DAS, the T\({}_{2\text{-}2}\) of these leaves did not differ significantly from that in the leaves of control plants. At the first stage, leaves from plants treated with TIMAC SL28 showed strong variability in T\({}_{2\text{-}2}\) and no significant differences in the leaves from control and water stressed plant were detected. At the second stage (57 DAS), T\({}_{2\text{-}2}\) in leaves treated with TIMAC SL28 was equivalent to the T\({}_{2\text{-}2}\) of leaves of control or water stressed plants. In leaf rank 8, the T\({}_{2\text{-}2}\) measured in control plant leaves was lower than in LR4 at both stages (around 110 ms at 42 DAS and around 120 ms at 57 DAS) (Figure 4c,d). In this leaf rank, T\({}_{2\text{-}2}\) was lower in the leaves of water stressed plants regardless of the stage (around 90 ms, and around 100 ms respectivly). At the first stage (42 DAS), the impact of water stress on T\({}_{2\text{-}2}\) was limited by the addition of TIMAC SL28. At the second stage (57 DAS), the T\({}_{2\text{-}2}\) measured in S-Ti leaves was equivalent to that measured in the leaves of water stressed plants, showing no effect of the biostimulant. As for all the other peaks, T\({}_{2\text{-}3}\) of old leaves were longer than those of mature leaves, the T\({}_{2\text{-}3}\) in the older leaves (LR 4) of control plants is 500 ms at 42 DAS and increased to 550 ms at 57 DAS. At 42 DAS, water stress led to a significant decrease in T\({}_{2\text{-}3}\). At 57 DAS, the T\({}_{2\text{-}3}\) in the leaves of water stressed plants had increased to reach the value of the T\({}_{2\text{-}3}\) measured in the leaves of control plants, so the effect of water stress on the T\({}_{2\text{-}3}\) was no longer significant after 15 days. In leaf rank 8 of control plants, T\({}_{2\text{-}3}\) increased from around 230 to 340 ms between the two stages (Figure 4e,f). The water stress induced a significant decrease in T\({}_{2\text{-}3}\) at the two stages (T\({}_{2\text{-}3}\) around 210 and 260 ms respectively). The addition of TIMAC SL28 did not lead to any difference in the T\({}_{2\text{-}3}\) in the LR 8 leaves of control and water stressed plants. Regardless of the development stage, the T\({}_{2\text{-}3}\) in leaves from S-Ti plants did not differ significantly either from control or water stressed plants. The LWW\({}_{1}\) of LR 4 was around 75 g\(\cdot\)m\({}^{-2}\) in control plants and remained constant at both stages (Figure 5a,b). Moreover, no significant effect of water stress was observed on the amount of this water fraction. The addition of TIMAC SL28 significantly increased the amount of water associated with this peak in the leaves of both leaf ranks but only at 57 DAS.