Effects of Nitrogen, Azoxystrobin and a Biostimulant Based on Brown Algae and Yeast on Wild Rocket Features at Harvest and During Storage

Abstract

Recently, the use of biostimulant substances of different origins has been affirmed. They act differently on the physiological processes of the plant, helping to improve its productive response and resistance to biotic and abiotic stress. Therefore, the response of the wild rocket to two substances known to have biostimulating activity (Azoxystrobin, and a fluid extract of brown algae and yeast), was evaluated. Two experimental trials (Exp 1 and Exp 2) were carried out in the greenhouse. The collected product, in addition to being evaluated from a qualitative point of view, was used for evaluation of shelf life. Exp 1 involved the comparison of two N levels with two Azoxystrobin levels (treated–Azo+, and untreated control). Exp 2 involved the comparison of two N levels, and two biostimulating substances based on Azoxystrobin (Azo+) and on fluid extracts of yeast and brown algae (YBA+), in addition to untreated control. A split-plot experimental design with three replications was used. Azo+ increased marketable yield of wild rocket by 16.8% and enhanced some qualitative features at harvest as the increase in chlorophyll (+17.8%) and carotenoids (+13.5%), and decrease in nitrates (−10.6%), regardless of the nitrogen level. Furthermore, Azo+ increased the shelf life (+2.5 days) of wild rocket stored at 3.5 °C. In particular, Azo+ slowed the loss of chlorophyll (yellowing) and the worsening of odor and visual appearance. As Azoxystrobin is a fungicide effective for the control of some diseases of wild rocket, its use should be promoted as it would offer not only the benefit of disease control but also improved production and shelf life. YBA+ caused an increase in the chlorophyll content (+12.5%) at harvest of wild rocket, but reduced its antioxidant activity (−40%). YBA+ did not cause substantial variations in shelf life with the exception of a slowdown in the degradation of carotenoids. Further research is desirable to evaluate other variables such as the dose and time of application.

Influence of Plant-Based Biostimulant (BORTAN) on Qualitative and Aromatic Traits of Rocket Salad (Diplotaxis tenuifolia L.)

“…This could be due to an increase in the amino acid content in LDPH-treated plants, which can enhance photosynthetic pigment production [ 5 ]. Furthermore, an increase in photosynthetic pigments has been reported in wild rocket treated with several PBs [ 25 , 26 , 27 ].…”

Net Photosynthesis and Biomass Production in Stevia, Eggplant, and Cowpea Can Be Improved by Fertilization with Cyanobacteria (Limnospira maxima)

“…This response is due to response limits, being effective only within a specific range of concentrations [58]. At low doses, they may not be concentrated enough to trigger a response, while at high doses, they may exceed the optimal range, resulting in a lack of the desired effect [59]. In contrast, in S. rebaudiana and S. melongena, elevated concentrations showed increases in the RDW, STW, LDW, and TDW.…”

Biostimulants of Different Origins Increase Mineral Content and Yield of Wild Rocket While Reducing Nitrate Content through Successive Harvests

“…The positive effects of biostimulants on the growth and yield of rocket plants have been previously reported in the literature, which revealed that biostimulatory products of varied composition had a beneficial effect. For example, Candido et al [24] suggested that the use of an azoxystrobin-based biostimulant may increase the marketable yield of wild rocket plants (Diplotaxis tenuifolia L. DC) after the first crop cycle, while positive effects on yield were also recorded for biostimulants that contained protein hydrolysates obtained from legumes, tropical extracts, Trichoderma harzianum, Moringa oleifera extracts and Azoxystrobin [14,[39][40][41][42][43]. Additionally, Di Mola et al [38] suggested a significant increase in fresh yield in wild rocket plants treated with a biostimulant that contained seaweed and alfalfa extracts and amino acids, especially for harvests performed in late spring.…”

“…The positive effect of biostimulants on horticultural crops is due to the bioactive compounds present such as amino acids and phytohormones that stimulate plant growth by altering the primary metabolism, in addition to modulating the secondary metabolism of plants, through the improvement of nutrient uptake and triggering phytochemical synthesis [2,3,12]. Furthermore, biostimulants can increase pigment levels in leafy vegetables, as well as their antioxidant capacity [1], improve leaf color [13] and reduce nitrate content by boosting nitrogen metabolism [14]. Nitrate is mainly consumed through vegetables [15,16]; therefore, consumers are concerned about its concentration, notwithstanding the fact that these vegetables are endowed with functional qualities.…”