Response of Cucumbers (Cucumis sativus L.) to Waste Wood Fiber Substrates and Additional Nitrogen Fertilization

As the consumption of plant products grown under regulated-climate conditions intensifies, its production also intensifies. Peat substrate as a growing medium is widely used due to its desirable physical, chemical, and biological properties. Peatlands play an important ecological, economic, and cultural role in human well-being, but their resources are decreasing, so wood fiber can be used as a substitute for peat substrate. Cucumbers (Cucumis sativus L.) were cultivated in growing media (Factor A) of peat substrate and wood fiber: (1) peat substrate (PS); (2) wood fiber (WF); (3) WF and PS 50:50 v/v; or (4) WF and PS 25:75 v/v. To evaluate the amount of additional nitrogen, four fertilization rates were used (Factor B): (1) conventional fertilization (CF); (2) N₁₃; (3) N₂₃; or (4) N₃₀. The yield of cucumbers grown in wood fiber depended on the amount of additional nitrogen. When plants were fertilized with the highest rate of additional nitrogen, N₃₀, their yield increased by 22% compared to the yield of cucumbers that were grown in wood fiber using conventional fertilization. Chlorophyll synthesis was the most intense in the leaves of cucumbers grown in wood fiber when the plants were additionally fertilized with N₂₃ and N_30, and in mixtures of wood fiber with peat substrate in ratios of 50:50 and 25:75, fertilized with N₂₃ and N₁₃, respectively. In summary, it can be argued that cucumbers can be grown in wood fiber and in a mixture with peat substrate in a ratio of 50:50, but additional nitrogen is needed to compensate for the amount of nitrogen immobilized in the fiber.