Evaluation of substitutes for rock wool as growing substrate for hydroponic tomato production
To reduce the rock wool waste, the present study is focused on the evaluation of sheep wool, Sphagnum and hemp slabs, which may be used as replacement for rock wool as growing substrate for hydroponic tomato production. As such, physical and chemical properties of substrates, the plant growth, yield, fruit characteristics, as well as primary and secondary metabolites of tomatoes were considered.
The marketable fruit yield of plants grown in Sphagnum slabs (12.8 kg plant-1) was reduced to only a small extent compared to the yield produced by rock wool slabs (13.8 kg plant-1). Sheep wool (12.3 kg plant-1) and hemp (10.4 kg plant-1), however, showed higher deviations. The lowest yield of blossom end rot (BER) fruit was produced by Sphagnum. Compared to this result, the BER-yield was nearly 2-fold higher caused by sheep wool. The soluble solid content in fruit ripened by the hemp material was decreased compared to those caused by the remaining substrates. Furthermore, it was found that the volume of easy available water (EAW) was mainly responsible for changes in plant development. As such, a high correlation was found between EAW and: leaf area (r = 0.851); flowers (r = 0.785); lycopene (r = -0.918); ß-carotene (r = -0.997); penolics (r = -0.918); LAA (r = -0.848).
The findings suggested that Sphagnum slabs can be used as replacement for rock wool slabs, whereas the usage of slabs consisting of hemp and sheep wool is not suitable as growing substrate for hydroponic tomato production.
From Volume 92 (2019) on, the content of the journal is licensed under the Creative Commons Attribution 4.0 License. Any user is free to share and adapt (remix, transform, build upon) the content as long as the original publication is attributed (authors, title, year, journal, issue, pages) and any changes are labelled.
The copyright of the published work remains with the authors. If you want to use published content beyond what the CC-BY license permits, please contact the corresponding author, whose contact information can be found on the last page of the respective article. In case you want to reproduce content from older issues (before CC BY applied), please contact the corresponding author to ask for permission.