## 1 Introduction  
Fertilization is the most important and controllable factor affecting the phytochemicals and nutritional value of vegetables. Biofumigation, an approach aimed at controlling pests and pathogens in soil, involves incorporating residues of _Brassica_ plants into the soil. As these residues decompose, they release toxic degradation products known as isothiocyanate (ITC), which can effectively combat various pests and soil-borne pathogens. GSLs are secondary metabolites present in seeds, roots, stems, and leaves of Brassicaceae vegetables including arugia, mustard, turnips, radish, broccoli, cabbage, cauliflower, and horseradish. GSLs are non-nutritional organic anions present in 16 dicotyledonous plant families in about 120 different chemical structures [1]. The concentration of GSLs has become an important parameter in developing plant varieties for human and animal welfare. They have a range of properties, such as antioxidant, herbicidal, and anticarcinogenicity [2]. GSLs-thioglucidase (myrosinase) chemical defense system is the bioactive mechanism in the Brassicaceae family. GSLs and thioglucosidase (the enzyme that breaks down GSLs) are located in two different compartments in Brassica cells that in combination release plant chemical defensive products [3, 4]. GSLs are water-soluble compounds deposited in the Brassica cell vacuole, whereas thioglucidase (myrosinase) is located in the phloem parenchyma cells and the mesophyll or cortex [5]. As a result, Brassica tissue interruption due to infestation or attack by arthropods causes the discharge of a complex mixture of GSLs that interrupt hydrolysis products of which ITCs (Figure 1) are powerful antimicrobial agents. Myrosinase in Brassica breaks the \(\beta\)-thioglucoside bond of the GSL molecule and releases one mole of ITC. Accordingly, one molecule of GSL yieldsone molecule of ITC and one molecule of glucose upon hydrolysis. ITCs might be useful as alternative agents for pest control as a replacement for the toxic metam sodium, a common fungicide [6], and/or methyl bromide and ethylene dibromide synthetic fumigants. Intact GSLs molecules have no toxic effect on fungi, whereas the hydrolysis products of GSLs inhibit the development of _Sclerotinia scleroorum_ and _Rhizactonia solani_ causal of plant stem rot [7]. Several investigators found that degradation products of the cut leaf or stem part of Brassica plants prevented the development of a diversity of soil diseases such as _Rhizactonia solan_, _Plutophthora erythrosceptica_, _Pythium ultimum_, _Sclerotinia scleroorum_, and _Fusarium sambucinam_[8] and pathogenic bacteria [9]. The chemical structure of GSLs can be categorized into three main groups: aliphatic GSLs, which primarily originated from methionine; aromatic GSLs, derived mainly from phenylalanine or tyrosine; and indoles GSLs, derived from tryptophan. All GSLs produce isothiyanate (ITC) and their production of ITCs is greatest at pH 7, whereas at acidic pH nitriles are mainly produced (Figure 1). Thioglucidase hydrolyzes GSLs in plants, insects, and fungi and is frequently found in soil [10]. Metam sodium, a synthetic commercial soil fumigant in the United States [6,11], also degrades to methyl ITC, which is utilized for the control of soil-borne fungi and nematodes. However, metam sodium is an extremely toxic compound that causes severe damage to the immune system [6]. Numerous research studies have explored the potential use of Brassica plants as environmentally friendly fumigants [12, 13, 14, 15, 16, 17]. [PERSON] [16] found that the levels of GSLs in collard plants (_Brassica oleracea_ cv. Top Bunch) grown in soil treated with sewage waste sludge (SS) and chicken manure (CM) were significantly higher compared to those grown in native control soil. Additionally, the organic matter content in the soil increased from 2% in native soil to 4 and 6.5% in soil supplemented with SS and CM, respectively.