Olive Mill Waste as a Substitute Growing Medium Component in Tomato Seedling and Crop Production

Abstract

Olive (Olea europaea L.) mill waste disposal has led to a growing concern regarding the impact to the environment and human health. Several soil amendments have been used to improve the physical and chemical characteristics of root zone profiles and mixes. Olive mill waste (OW; olive stone and pulp) in ratios of 10%, 30%, or 50% was used for tomato (Solanum lycopersicum L.), cv. Luana, seedling production and at 10% or 30% for greenhouse tomato cultivation. Substrates containing peat and OW suppressed plant emergence and increased mean emergence time. Seedling height and biomass was reduced when OW (especially at 50%) was added to substrates, but no differences were observed in the number of leaves produced. Under greenhouse conditions, adding OW (10%–30%) in soil reduced plant height and stem diameter up to 25% compared to the control, but no differences were observed in leaf number. Plant upper biomass and root fresh weight was similar in the 10% OW and control treatments but reduced in 30% OW. Plant yield decreased (up to 36%) when 30% OW was used due to decreased fruit number rather than fruit weight. Addition of OW (10%–30%) maintained fruit firmness but decreased tomato juice pH and electrical conductivity (EC), but no differences were observed in fruit total soluble solids. The EC and K and Na contents of the nutrient were greater in outflow from OW mixtures compared to the control; no differences occurred for pH and Ca content. After a 10-week period, plants grown in 30% OW exhibited phytotoxicity symptoms and reduced growth. Use of 10% OW can be used for seedling production and in greenhouse tomato crop production, maintaining yield and fruit firmness.

Keywords:

• Olea europaea
• Solanum lycopersicum
• Emergence
• Growth
• Peat
• Perlite
• Plant