Influence of Preharvest Gibberellic Acid Treatments on Postharvest Quality of Minimally Processed Leaf Lettuce and Rocket

Abstract

Plant growth regulators are used in high-value vegetable crops during cultivation and after harvest to increase yield, enhance crop management, and improve or retain the produce quality. The aim of this work was to evaluate the quality characteristics during cold storage of minimally processed leaf lettuce and rocket, obtained from plants grown in a hydroponic floating system with mineral nutrient solutions (MNS) containing different levels of gibberellic acid (GA3). Plants were grown in greenhouse conditions on nutrient solutions containing 0, 10−8, and 10−6 M GA3. At harvest, lettuce and rocket were immediately processed as fresh-cut vegetables and stored for 21 d at 4 °C. After processing, weight loss, total soluble solids, titratable acidity, ascorbic acid and nitrate content, leaf color characteristics, and overall quality were evaluated. Adding 10−6 M GA3 to the MNS of a floating system significantly increased the yield of leaf lettuce and rocket plants and of minimally-processed leaves. In addition, preharvest GA3 treatments had positive effects on delaying senescence and enhancing shelf-life of minimally processed lettuce and rocket. The slowed senescence of GA3-treated samples maintained an overall quality over the threshold of marketability in both lettuce and rocket for up to 21 d of cold storage.

Use of Gibberellic Acid to Increase the Salt Tolerance of Leaf Lettuce and Rocket Grown in a Floating System

“…This goal was obtained in rocket plants grown with 20 mM NaCl in the MNS whereas salt stress did not affect the nitrate content of lettuce, showing that the root system of these species could differ in uptake capacity. Differences were also found in their response to GA 3 treatments as regards the nitrate content of the leaves as also found in previous works [24,32]. As already discussed, GA 3 positively affected NUE and this may be due to the effect of gibberellic acid on improving nitrogen utilization by enhancing N metabolism and its redistribution in the plants [31].…”

“…Crispa) and rocket (Eruca sativa L.). Six treatments derived from a factorial combination of three NaCl concentrations (0, 10, and 20 mM NaCl) and two GA 3 concentrations (0 and 10 −6 M GA 3 [24,32]; Gibrelex, Biolchim, Bologna, Italy) were tested for each species.…”

“…Yet, studies on the effects of gibberellic acid application on leafy vegetables grown in hydroponics are rather scant. Miceli et al [24,32] found that the supplementation of 10 −6 M GA 3 through the nutrient solution of hydroponically grown leaf lettuce and rocket can exert a significant effect on the yield, quality, and post-harvest life of these vegetables. Thus, the exogenous application of GA 3 trough the nutrient solution could also affect the salt tolerance of leafy vegetables.…”

Effect of Agronomic Practices on Yield and Quality of Borage at Harvest and During Storage as Minimally-Processed Produce

“…As reported by others authors for various leafy vegetables [26,[35][36][37][38][39], minimally-processed vegetables packed in sealed plastic bags characterized by low permeability to water vapor do not suffer dehydration due to the very high Consumer's perception of vegetable quality is mainly influenced by their color and appearance; thus, color modifications and overall appearance are the primary parameters for the quality evaluation of vegetables, especially those minimally-processed [44,48]. These modifications may occur due to both pre-harvest [48][49][50][51][52] or post-harvest [17,19,[35][36][37]53,54] factors. The color variability of borage leaves was mainly due to the difference between the tested borage accessions as already reported for chlorophyll content; accession H had leaves more yellowish (higher a* values) and greenish (higher b* values), resulting in a more vivid color (chroma) than accession D4 (Table 4).…”

“…Ascorbic acid is considered a very labile compound that can quickly degrade during storage at ambient temperature. Nonetheless, cold storage of vegetables packed in sealed bags showed to strongly slow down its deterioration or even increase its content as found for borage, broccoli, green asparagus, carrots, Swiss chard, and rocket [19,26,49,53,[85][86][87]. These increases have been attributed to physicochemical changes or to unidentified enzymes that regenerate ascorbic acid [86].…”