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

Gianluca Caruso; Luigi Formisano; Eugenio Cozzolino; Antonio Pannico; Christophe El-Nakhel; Youssef Rouphael; Alessio Tallarita; Vincenzo Cenvinzo; Stefania De Pascale

doi:10.3390/plants9080933

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

Plants (Basel). 2020 Jul 23;9(8):933. doi: 10.3390/plants9080933.

Authors

Gianluca Caruso¹, Luigi Formisano¹, Eugenio Cozzolino², Antonio Pannico¹, Christophe El-Nakhel¹, Youssef Rouphael¹, Alessio Tallarita¹, Vincenzo Cenvinzo¹, Stefania De Pascale¹

Affiliations

¹ Department of Agricultural Sciences, University of Naples Federico II, 80055 Portici, Naples, Italy.
² Council for Agricultural Research and Economics (CREA)-Research Center for Cereal and Industrial Crops, 81100 Caserta, 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.

Keywords: Diplotaxis tenuifolia L. (D.C.); antioxidant activity; ascorbic acid; cropping seasons; leaf production; minerals; phenols; shading nets; sustainable management.