Flavonoids are important in plant interactions with the environment and may have positive effects on human health. Effects of light quality and quantity on flavonoid concentration were studied in baby spinach (Spinacia oleracea L.) cultivated under three types of shade netting differing in transmittance of UV-B and PAR, at two times during the season. Leaves harvested at two growth stages for each sowing were subjected to different post-harvest storage conditions. Shade nettings had a relatively small effect on flavonoid concentration in baby spinach. The largest effect was found when radiation was most intense. The nettings then decreased total flavonoid concentration by 15-24% at the normal commercial growth stage at harvest. Radiation and plant growth both affected flavonoid concentration, in opposite or similar directions depending on time of season. This variation was reflected in the statistical analysis, showing significant interactions among the factors. There were large differences (up to 100%) in flavonoid concentration between the different times of the season, in shaded as well as unshaded spinach. Flavonoid concentration and composition changed during storage, but no consistent difference was found between the shaded and unshaded leaves. In most cases, total flavonoid concentration increased significantly during the first 6 days of storage. In conclusion, the use of shade netting is acceptable for production of baby spinach as regards flavonoid concentration and composition.

Baby spinach ( Spinacia oleracea L.) was grown under three types of shade netting (high transmittance, spectrum-altering, and low transmittance) to study the effect on the concentrations of vitamin C (ascorbic acid and dehydroascorbic acid), carotenoids, and chlorophyll and on the visual quality of the leaves. The spinach was sown in April and August and harvested at two growth stages. After harvest, leaves were stored in polypropylene bags at 2 and 10 degrees C. Shading significantly decreased the ascorbic acid concentration of April-sown spinach by 12-33%, but in the August-sown spinach, the response was inconsistent. Concentrations of total carotenoids and total chlorophylls were significantly higher under the nettings in many cases, especially under the spectrum-altering and low-transmittance nettings. Postharvest visual quality and postharvest persistence of the compounds analyzed were not greatly affected by shading. We conclude that these shade nettings are acceptable to use in baby spinach production when it comes to the studied aspects of internal and external quality of the produce.

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