Siv Mari Aurdal
Post Doctor
Abstract
This study investigated the effects of substrates composed of various ratios of wood fiber and peat (0, 25, 50, 75, and 100% peat (v/v)) mixed with different amounts of lime (0, 2, 4, 6, and 8 g L−1) and start fertilizer (0, 2, and 4 g L−1 Multimix) on the growth and biomass accumulation of petunia (Petunia x hybrida Vilm ‘Finity F1 Purple’) and basil (Ocimum basilicum L. ‘Marian’) in an ebb-and-flow greenhouse system. Growth parameters included plant height, weight, canopy diameter, and chlorosis symptoms for petunia, along with substrate pH and EC measurements. Petunia showed optimal growth in substrates with higher peat content, while basil produced satisfactory biomass across a pH range of 5–7 regardless of substrate type. Optimal petunia cultivation in 100% wood fiber required a significant dose of start fertilizer without lime. Monitoring pH and EC using pour-through and press methods revealed a pH decrease in substrates with added start fertilizer, while substrates with higher wood fiber content were less acidic. Substrates with over 50% (v/v) wood fiber without lime showed a rapid pH increase over five weeks. The pour-through method generally underestimated EC values compared to the press method. These findings contribute to optimizing the wood fiber/peat blends for sustainable horticulture.
Abstract
The aim of this study was to compare various types of peat-free or peat-reduced growing media on growth and flowering of ‘Purple piruette’ petunia hybrids. In experiment 1, 30 variants of growing media, including commercial peat-based growing media, different peat-reduced and peat-free mixtures based on garden/park waste compost and wood fiber were tested. All the peat-free variants failed in producing normal, healthy plants without chlorosis. A commercial peat-reduced growing medium with peat, garden/park waste-compost and crushed rock material (0-2 mm), base fertilized with chicken manure, and similar growing media mixtures with other types of base fertilizer gave larger plants with more flowers than the peat-based reference. The highest performing mixture with the smallest amount of peat (35% wood fiber, 30% garden park/park waste-compost, 30% peat and 5% sand) gave equal results as the commercial peat-reduced growing medium. In experiment 2, further studies of the effect of peat reduction by incorporation of wood fiber and four compost types were performed. The effect of start fertilizer incorporation to the substrates was also assessed. One of the peat-free variants with compost and wood fiber gave normal plants with rich flowering but didn’t reach the performance of pure peat on plant size. The pH (H2O) of the composts seems to be a key factor for successful substrate mixtures of compost and wood fiber. The composts with highest pH gave small plants and start fertilizer had no effects on the growth. The results show that there is a potential for development of peat-free substrates based on compost and wood fiber presuming that pH (H2O) of the composts is not too high.
Abstract
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