Compost-based substrate for Gazania rigens (L.) cultivation.

In ornamental potted plant production, the use of compost from various organic sources promote peat-free substrates and sustainable disposal of organic wastes. The aim of this experiment was to evaluate the use of pruning waste compost to replace peat for Gazania rigens cultivation. Compared to peat-based substrate commonly used in the nursery (T1, with 60% of peat), three substrates were prepared increasing compost volumes in substitution of peat (T2: 20%-40%; T3: 40%-20%; T4: 60%-0%, compost-peat respectively, v/v). Before transplanting, substrates were previously treated in order to adjust pH and level of nutrients. The irrigation was scheduled on the basis of the water release curve of the different growing media. Results indicated that plants grown in T2 and T4 showed an higher dry and fresh biomass, leaf area and number of leaves, compared to T1 and T3. The K+, Ca2+, Cl-and Na+concentrations in plant tissues increased linearly with the rise of compost in the substrate. On the contrary, nitrogen concentration was the lowest in plants grown with the highest volume of compost in the substrate. In conclusion compost from pruning waste can partially or totally replace peat for gazania pot cultivation.