# Effect of Seawater Irrigation on the Sugars, Organic Acids, and Volatiles in 'Reliance' Grape
## 3 Results
### Effect of Seawater Irrigation on Aroma in 'Reliance' Grape at Growing Stages  
The volatiles of \"Reliance\" berries during the growing stages were analyzed to explore the effect of 10% seawater irrigation on the aroma of grapes. From Figure 4a, it can be concluded that during EL 31-38, the total aroma first decreased slightly and then increased during fruit development from EL 35. In general, the 10% seawater treatment significantly increased the total aroma of berries relative to the control berries. Treatments S1 and S2 significantly increased the fruit aroma content from stage EL 36, but the volatiles of treatment S3 were not significantly different from the control. At 38, the total berry aroma in the S1 and S2 groups was increased by 26.94% and 14.13%, respectively, compared with the control. Moreover, the total aroma of S3 berries was decreased by 4.14% relative to the control. The aroma of \"Reliance\" berries was classified into three categories according to the precursors and synthetic routes: isoprene pathway aroma, fatty acid pathway aroma, amino acid pathway aroma. Evaluation of the aroma concentrations according to the three pathway categories revealed an initial rise and then a decrease, with a similar trend for the total aroma (Figure 4b-d). Of note is the decrease in the isoprene and amino acid pathways aromas that occurred at EL 36 and 37, but which occurred at EL 33 and 35 for the fatty acid pathway aroma. At EL 38, treatments S1 and S2 significantly increased the aroma content of isoprene and fatty acid pathways, relative to the control. No obvious trend was found in the aroma of the amino acid pathway between treatment S1, S2, S3, and the control. The concentrations of C6 aldehydes, C6 esters, hexanal, and ethyl acetate were measured to further analyze the dynamic changes of representative volatiles of \"Reliance\" berries (Figure 4e-h). As the main volatiles synthesized in the upstream of the fatty acid pathway, the trends of C6 aldehydes were similar to the fatty acid pathway aroma (Figure 4e); C6 esters, showed a continuously rising trend over the entire course of fruit development (Figure 2f). At EL 38, the concentrations of C6 aldehydes in S1, S2, and S3 groups were significantly increased by 12.50%, 13.71%, and 4.06% relative to the control group, respectively. Furthermore, the content of C6 esters in the control berries was 40.58% and 13.69% lower than the S1 and S2 berries, respectively, and 27.93% higher than that of the S3 berries at EL 38 (Figure 4f). The content of hexanal and ethyl acetate, the most considerable portion of aldehydes and esters, in the S1 berries were increased by 19.84% and 70.62% at EL 38, respectively, relative to the control (Figure 4g,h). Figure 4: Effect of seawater irrigation on aroma in ‘Reliance’ grape at the growing stage. (**a**) Total aroma, column colors represent different treatments, and column textures represent different aroma pathways (**b–d**) changes of aroma in isoprene, fatty acid, and amino acid pathways, (**e,f**) changes of total aldehydes and esters in the fatty acid pathway, (**g,h**) changes of two main contributors of aldehydes and esters. Values are the means of three replicates, and error bars denote the SD. Different lowercase letters indicate significant differences of samples in one developmental phase, according to [PERSON] multiple comparison post-hoc test at \(p<0.05\). Effect of seawater irrigation on the Concentrations and Types of volatiles in 'Reliance' Grape at EL 38  
Table 3 shows the effect of 10% seawater irrigation on volatiles originating from different/same precursors and synthetic routes at EL 38. It can be seen that S1 treatment significantly increased most volatiles of the isoprene pathway and C6 esters of the fatty acid pathway. The highest contents of the amino acid pathway volatiles were mostly found in treatment S3.