# Effect of Seawater Irrigation on the Sugars, Organic Acids, and Volatiles in 'Reliance' Grape
## 3 Results
### Effect of 10% Seawater Irrigation on the Concentration of Sugar and Organic Acids  
As shown in Figure 3, the content of total soluble solids (TSS), soluble sugar, glucose, and fructose increased continuously during the growth and maturity of \"Reliance\" berries. Overall, 10% seawater irrigation in different periods enhanced the content of TSS, soluble sugar, glucose, and fructose in treated berries relative to the control berries. At EL 38, the TSS content of grapes in S1, S2, and S3 treatments increased by 1.87%, 1.80%, and 0.74%, respectively, compared with the control berries (Figure 3a); the soluble sugar content increased by 33.77%, 21.43%, and 15.69%, respectively (Figure 3b); the glucose content increased by 23.62%, 16.69%, and 14.31%, respectively (Figure 3c); the fructose contents increased by 38.69%, 34.65%, and 22.78%, respectively (Figure 3d). More importantly, the S1 treatment significantly affected the TSS, soluble sugar, glucose, and fructose content in the fruits from the EL 33 period; the S2 treatment had a significant impact on the TSS, soluble sugar, glucose, and fructose content in the fruit from the EL 35 period. For the S3 treatment, significant differences first appeared at EL 36. This result indicates that the sooner 10% seawater is irrigated, the earlier the sugar content is improved. In the last period, EL 38, berries of the S1 group showed higher content of TSS, soluble sugar, glucose, and fructose compared with the S2, S3, and the control groups.  
Figure 2: Effect of seawater irrigation on the texture of ‘Reliance’ grapes. (**a**) Skin hardness, (**b**) frangibility, (**c**) firmness, (**d**) average hardness of flesh. Values are the means of fifty 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 \(p<0.05\).  
Figure 3: Effect of seawater irrigation on the sugar and organic acid content of the ‘Reliance’ grape. (**a**) Total soluble solids, (**b**) soluble sugar, (**c**) glucose, (**d**) fructose, (**e**) titratable acid, (**f**) tartaric acid, (**g**) malic acid, (**h**) citric acid. Different lowercase letters indicate significant differences of samples in one developmental phase, according to [PERSON] multiple comparison post-hoc test at \(p<0.05\).  
The tittatable acidity decreased during the entire growth of \"Reliance\" berries, with malic acid, tartaric acid, and citric acid showing similar trends (Figure 3e-h). Malic acid was the most abundant organic acid in the early stages (EL 31-35), tartaric acid was the primary organic acid in the later stage of veraison to maturity (EL 36-38), and the content of citric acid was less than 1 g kg\({}^{-1}\) over the whole course of fruit development. More importantly, 10% seawater irrigation significantly decreased the content of tittatable, malic, tartaric, and citric acids in berries at EL 36-38. The significant differences as the consequence of 10% seawater treatment began from EL 35 or EL 36. By EL 38, the content of tittatable, malic, tartaric, and citric acids in S1, S2, and S3 groups were significantly lower than the control group. The most significant reduction was in the S1 group, S2 was the second, while S3 had the least. At EL 38, the content of tittatable acid in S1, S2, and S3 berries were 18.28%, 16.98%, and 13.59% lower than the control, respectively (Figure 3e); the tartaric acid was decreased by 36.44%, 25.13%, and 11.48%, respectively (Figure 3f); the malic acid levels were reduced by 34.51%, 30.72%, and 25.79%, respectively (Figure 3g); the content of citric acid were 37.61%, 20.13%, and 8.65% lower than the control berries, respectively (Figure 3h).