A new substrate for the cultivation of pomegranate

The accumulation of dredging materials extracted from seaports, as well as their removal, could be a problem from the environmental point of view since their composition are considered as contaminating materials. It has been wanted to show the suitability of this sediment without any use for the moment as a new substrate in agriculture. In addition, it would avoid the gradual exhaustion of some traditional substrates, such as peatlands. For these reasons, the effect of sediments, obtained from the dredging of the Leghorn Port (Italy) and partially decontaminated (bioremediation), has been studied in comparison with traditional substrate (peat). The effects of the substrate on the growth of pomegranate trees (Punica granatum L. 'Purple Queen') were studied in Orihuela (SE Spain), during 2016. According to the substrate used, three treatments were established: control (traditional peat 100%), mixture Peat-DRS (50% traditional peat and 50% dredged remediated sediments), and 100% dredged remediated sediments (DRS). Each treatment consisted of three replications in a randomized complete block design (RCBD). Trunk diameter, height, leaf surface, color of upper side, pruning weight, chlorophyll content, leaf dry matter and leaf analyses (nutrients and pollutants) were determined for each treatment. The results indicated that the different treatments studied no shown significant differences in height tree and trunk diameter evolution, leaf upper side color, leaf surface, leaf chlorophyll content and pruning weight, although the DRS and Peat-DRS treatments showed higher values for leaf dry matter accumulation than control treatment. Although this study should extend to several years, the absence of significant differences in the tree growth, suggests the possibility of using this new substrate either alone (DRS) or mixed with some traditional substrate (Peat-DRS).