Changes in Antioxidant Metabolism and Plant Growth of Wild Rocket Diplotaxis tenuifolia (L.) DC cv Dallas Leaves as Affected by Different Nutrient Supply Levels and Growing Systems

Abstract

It has been widely assessed that the quality and quantity of nutrient supply and the growing system can strongly affect the growth and development of plants, the nutritional quality, and the levels of minerals, phytochemicals, and vitamins. The study was conducted on leaves of wild rockets grown in soil and soilless to examine the effect of growing conditions and mineral fertilization doses on the quality, mineral content, enzymatic and non-enzymatic antioxidants, and oxidative stress. The experiment was conducted in a plastic greenhouse into two independent sectors, one for soil-bound cultivation and another equipped for soilless cultivation. The crop was subjected to a high compared to a low-input fertilization program. Ion exchange chromatography, spectrophotometrically, and microbiological techniques were utilized. The soil-bound treatments increased the fresh weight, leaves number, chloride content, and microbial load. Exogenous application of higher nitrogen levels significantly boosted the ascorbate and hydrogen peroxide levels. Wild rocket growth in soilless showed a higher content of sulphates and polyphenols, and enhanced activity of the antioxidant enzymes dehydroascorbate reductase and monodehydroascorbate reductase. The fertilization rate and the cultivation system did not modify the content of nitrates, except in the soilless system treated with high fertilization program, where nitrate levels slightly exceeded regulatory limits. The yield and overall quality of wild rockets can be improved by combining the proper fertilizer dose with the growth system (soilless or soil) and suggested fertilization management is provided.