Managing traditional and soilless culture systems to produce corn salad (Valerianella olitoria) with low nitrate content and lasting postharvest shelf-life.

摘要

Corn salad (V. olitoria [V. locusta]) is traditionally cultivated in soil and commercialized as ready-to-eat produce. Soilless culture system (SCS) allows clean leaf production, easing and shortening postharvest handling in process industries, and to control growth factors. A comparison between the traditional culture system (TCS) and a SCS was conducted, with 2 plant densities (1067 and 2134 plants/m2). TCS was simulated in polystyrene trays filled with local soil and peat (1:1 v/v), overhead irrigation, and weekly fertilizer application. Forty-cell trays for SCS, filled with 1:1 perlite and peat, were floated in a nutrient solution. At harvesting, plants were package and refrigerated for postharvest shelf-life (8 days) evaluations. After 40 days, plants from SCS were marketable. Production was significantly affected by culture system x plant density interactions. Greater yield was obtained in SCS, particularly with high plant density (1668 g/m2). Reduced leaf nitrate content was obtained in both systems, reaching 132 and 333 mg kg fresh weight with TCS and SCS, respectively; these values were below the 2500 mg/kg acceptable threshold. During storage, leaf weight loss was ~1% and not affected by the cultural techniques. SCS produced high quality marketable plants in 40 days, with low nitrate content, while TCS required an extended growing period.