Effect of Foliar Spraying with Different Sources of Calcium on Browning, Quality and Storability of Lettuce Crop

This study examined the influence of foliar spray containing various sources of calcium (calcium chloride, calcium nitrate, and calcium oxide) at two different concentrations (1% and 2%) of lettuce (cv. Iceberg). The study was carried out over two consecutive winter seasons (2021-2022 and 2022-2023), comparing treated plants with untreated control plants (sprayed only with water) on total yield, quality characteristics and storability of lettuce heads. Results showed that the plant treated with calcium nitrate at 1% or 2% was the most favorability treatment for enhancing the total yield/plot, head weight and number of leaves/head. However, plant treatment with calcium chloride at 2% treatment improved physical properties of head (head compactness, firmness, and dry weight) and chemical properties [ascorbic acid, total chlorophyll content, and total phenolic compounds (TPC)], also, gave the lowest values of browning% of the leaves at harvest and increased storability of heads, which provided the lowest weight loss value, browning (score), polyphenol oxidase (PPO) activity, maintained head firmness, total soluble solids, ascorbic acid, total chlorophyll content, and (TPC) during the storage period and gave heads with an excellent appearance without any decay after 20 days of storage at 0 ºC.