Shading Affects Yield, Elemental Composition and Antioxidants of Perennial Wall Rocket Crops Grown from Spring to Summer in Southern Italy

Abstract

Shading nets have been increasingly drawing research interest, as they allow us to improve the environmental conditions for greenhouse-grown crops. The effects of two shading nets (50% and 79% shading degree), plus an unshaded control, on yield, mineral composition and antioxidants of perennial wall rocket (Diplotaxis tenuifolia L.-D.C.) grown under tunnels in southern Italy were determined. The shading application resulted in a yield decrease, compared to the unshaded control, except for the highest production under 50% shading in July. The highest yield was recorded in the April–May and May–June and the lowest in July. Similar trends were recorded for plant dry weight, leaf number per rosette and mean weight, but the latter showed the highest value under 79% light extinction in July. The rocket leaves were brighter in the summer cycles than in the spring ones. Leaf nitrate was highest in spring and under 79% shading. Potassium, phosphorus, calcium and magnesium showed the highest values in spring and in the unshaded control. The lipophilic antioxidant activity showed the highest values under the 79% shading net in the spring cropping seasons, whereas in July it did not significantly differ from 50% light extinction. The hydrophilic antioxidant activity always attained the highest values in the unshaded control. The unshaded leaves had the highest total phenol accumulation when grown in April–May and the lowest in July. The total ascorbic acid content was always highest in the unshaded control leaves compared to the shading treatments. Fifty percent crop shading is, therefore, an effective sustainable tool for increasing the yield of perennial wall rocket leaves in July, when the light intensity under the plastic tunnel exceeds the plant requirements, also resulting in a mineral composition that is not significantly different from that of the unshaded crops.

Effect of Colored Shading Nets on the Growth and Water Use Efficiency of Sweet Pepper Grown under Semi-arid Conditions

“…There was no significant influence of shading treatments on the leaf mineral contents (i.e., N, P, K, and Ca) of sweet pepper in this experiment (Table 3). This result agrees with that of Caruso et al (2020), who found that the mineral composition of the shaded perennial wall rocket (Diplotaxis tenuifolia) plants was not significantly different from that of the unshaded crops.…”

“…Under such stressful environments, there is an ever-increasing need to improve and understand environmental controls that can enhance plant growth and production (Ili c et al, 2017). The extreme variabilities in air temperatures and solar radiation during the crop growing seasons have been shown to be vital to plant growth and yield (Caruso et al, 2020). However, only solar radiation intercepted by the crop can contribute to photosynthesis (D ıaz-P erez, 2013) improved as shading levels were increased (Kittas et al, 2012).…”

Assessment of Yield and Nitrate Content of Wall Rocket Grown under Diffuse-Light- or Clear-Plastic Films and Subjected to Different Nitrogen Fertilization Levels and Biostimulant Application

“…In addition, nitrogen assimilation and accumulation are strongly linked to nitrate reductase activity, a process strongly affected by light [13]. The effects of light and fertilization are opposite; the nitrate content in green plant tissues has a direct relation with N fertilization and inverse with light [4,5,11,[14][15][16][17][18]. Since the light intensity varies during the season, the nitrate content also shows a seasonal behavior.…”

Foliar selenium fertilization alters the content of dietary phytochemicals in two rocket species

“…We again used E. sativa and D. tenuifolia for consistency, and because these species differ in the content of health-promoting phytochemicals, have a wide distribution, and are of increasing importance after the circulation of the ready-to-use salads in the vegetable retail markets ( Heimler et al, 2007 ; Caruso et al, 2020 ). The species E. sativa , in particular, has been artificially selected and this may have led to some biochemical and physiological differences with D. tenuifolia .…”