Preharvest salicylic acid treatments to improve quality and postharvest life of table grapes (Vitis vinifera L.) cv. Flame Seedless

Abstract

Significance of preharvest salicylic acid (SA) treatments on maturity, quality and postharvest life of grape cv. Flame Seedless were studied during two years. The experiment was performed on 12-year old own rooted, grapevines planted at 3 m × 3 m spacing trained on overhead system. Vines were treated with aqueous solutions of SA (0.0, 1.0, 1.5 and 2.0 mM) at pea stage and at veraison. After harvesting, clusters were divided into two lots in which one was subjected to initial quality evaluation, while the other was stored in cold room (3-4 °C, 90-95 % RH) for evaluation of postharvest quality. SA at the dose of 1.5 and 2.0 mM hastened berry maturity by 3 to 5 days, produced less compact bunches alongside larger berries in contrast to control and the lowest dose. The same doses effectively maintained peel colour, higher firmness, lower pectin methyl esterase activity and electrolyte leakage alongside suppressing degradation of TSS and TA during cold storage. These two doses also exhibited higher efficacy on maintaining anthocyanins, phenols and organoleptic properties while reducing weight loss, rachis browning and decay incidence. Correlation analysis demonstrated that many quality parameters are interdependent. In conclusion, preharvest spray of 1.5 mM SA proved to be an effective means of improving quality and extending postharvest life of grape cv. Flame Seedless.

Keywords: Quality; Salicylic acid; Shelf life; Table grapes; Vitis vinifera L.

Fig. 1

Variation in berry firmness (panel a) and enzymatic activity of pectin methyl esterase (PME, panel b) of grape cv. Flame Seedless during cold storage (3–4 °C, 90–95 % RH) in relation to different treatments of salicylic acid. Results represent pooled data of two seasons in 2012 and 2013.Vertical bars represent ± S.E. of means for 6 replicates (3 per season), (0.0, 1.0, 1.5 and 2.0 are salicylic acid concentrations in mM)

Fig. 2

Variation in peel colour (L ^*, a ^* and b ^*) of grape cv. Flame Seedless during cold storage (3–4 °C, 90–95 % RH) in relation to different treatments of salicylic acid. Results represent pooled data of two seasons in 2012 and 2013.Vertical bars represent ± S.E. of means for 6 replicates (3 per season, n = 30 berries), (0.0, 1.0, 1.5 and 2.0 are salicylic acid concentrations in mM)

Fig. 3

Variation in total anthocyanin content (TAC, panel a) and total phenol content (TPC, panel b) of grape cv. Flame Seedless during cold storage (3–4 °C, 90–95 % RH) in relation to different treatments of salicylic acid. Results represent pooled data of two seasons in 2012 and 2013.Vertical bars represent ± S.E. of means for 6 replicates (3 per season), (0.0, 1.0, 1.5 and 2.0 are salicylic acid concentrations in mM), GAE: gallic acid equivalents

Fig. 4

Variation in physiological loss in weight (panel a) berry shatter (panel b), decay incidence (panel c) and membrane electrolyte leakage (MEL, panel d) of grape cv. Flame Seedless during cold storage (3–4 °C, 90–95 % RH) in relation to different treatments of salicylic acid. Results represent pooled data of two seasons in 2012 and 2013.Vertical bars represent ± S.E. of means for 6 replicates (3 per season, n = 2 kg clusters), (0.0, 1.0, 1.5 and 2.0 are salicylic acid concentrations in mM)