No abstract

This study investigated the effect of deficit irrigation at three management allowable depletion levels (MAD) 25%, 50%, and 75% on phytochemicals, ascorbic acid, antioxidant activity, glucose, fructose, and fresh and dry mass in two green leafy lettuce cultivars (Lollo Bionda and Vera) at harvest. Genotype response was observed during deficit irrigation on fresh and dry mass at harvest. Vera revealed similar fresh mass at MAD levels 25% and 50%. Chicoric acid, caftaric acid, and chlorogenic and caffeic acid tended to increase at 50% MAD, while kaempferol, quercetin, and myricetin increased at 75% MAD in both cultivars indicating increasing antioxidant properties. Ascorbic acid content declined with increasing MAD levels and no definite trend on β‐carotene content was noted in these cultivars with respect to MAD irrigation. Deficit irrigation at 50% and 70% increased glucose concentration in cv. Lollo Bionda. Deficit irrigation influences the abiotic stress condition that stimulates the biosynthesis of phytochemicals in plants and improves crop quality. However, deficit irrigation can affect marketable crop yield. Based on findings of this study, the lettuce cv. Vera can be recommended as a suitable cultivar for deficit irrigation (at MAD 50% levels) for improving dietary phytochemicals and crop quality without compromising fresh mass for marketing.

This study was initiated to investigate the impact of transportation, storage, and retail shelf conditions on lettuce quality and phytonutrients losses in the urban fresh produce market supply chain. Reducing postharvest losses is a priority to reduce the loss of the dietary‐based phytonutrients and to improve the health of the consumers. Limited information is available in South Africa related to the postharvest and nutrition loss in the urban fresh produce market supply chain. In this study, we quantified the postharvest losses, changes in phytochemicals, and loss of minerals in lettuce at different points of Tshwane Fresh Produce Market supply chain. Lettuce supply to the Tshwane Fresh Produce Market from two different provinces, Gauteng and North West, were included in this study for comparison. Lettuce from the two provinces was collected from five different farms. The loss of fresh weight, changes in visual quality, phytonutrition properties, and economic loss of lettuce at the supply chain points: (a) transport; (b) storage; (c) and at the retail shelf was investigated. Five boxes of lettuce per supply chain point from Gauteng and North West provinces were randomly selected. The results indicated that the high temperature (25°C) and low RH (40%) at the retail shelf affected the weight, overall quality, and phytonutrition properties of lettuce. Cumulative economic loss was higher at the retail shelf due to the inferior quality of lettuce. The study identified where major quality and phytonutrition losses occur during marketing. The study demonstrated to identify the where major food and nutritional loss losses occur during marketing. This information will significantly benefit food sustainability by introducing technologies to manage food and nutrition losses.