Effect of Anaerobic Digestates Application on Qualitative Traits in Early and Late Cauliflower

The use of anaerobic digestates coming from organic matrices as fertilizers, in reference to qualitative and nutritional traits in cauliflower was evaluated. These matrices plays nowadays an increasing importance since they could be employed as a source of organic matter and nutrients to the soil. The sludge used derived from the anaerobic digestion of plant material as by product obtained from fruit distillation. The experiment was conducted at the University of Padova considering two varieties of cauliflower (early and late). The following treatments were considered: control unfertilized (F0), treatment with mineral fertilizers (FMIN) in which the 100% of the nitrogen requirement was supplied in mineral form, 50% of the nitrogen requirement was made in mineral form and the remaining demand with digestate (F50), 75 % of nitrogen requirements was supplied with digestate (F75) and 100% of demand in nitrogen was supplied through digestate (F100). Dry matter content, antioxidant capacity (AOA), total phenols (TP), ascorbic acid (AA), phenolic acids, organic nitrogen and nitrate (NO3) were evaluated as qualitative traits in corymb. It was also determined the quantity of Al, Ca, Cu, K, Mg, P, Zn and heavy metals (Cd, Cr, Hg, Ni, Pb). Concerning the dry matter content, F0 plants and the early variety showed higher values. About AOA, TP, AA and phenolic acids all treatments showed high values and none of them was influenced by fertilization. Antioxidant compounds content was affected also by genotype and the early variety showed the highest values. In assessing the percentage of organic nitrogen and NO3 values, no differences were found in the first case and the NO3 content was very low in all treatments. Heavy metals content was very low or absent in the edible part. High levels of mineral compounds were found in early cultivar and they were not influenced by digestate application.