Effect of Re-Used Lignite and Mineral Wool Growing Mats on Plant Growth, Yield and Fruit Quality of Cucumber and Physical Parameters of Substrates in Hydroponic Cultivation

Abstract

In hydroponic cultivation of vegetables with a solid substrate, mineral wool predominates. The pro-ecological policy and consumers’ expectations cause an increase in interest in organic substrates, which, when properly used, are less harmful to the environment. The aim of this study was to determine the effect of reusing lignite substrate in hydroponic cultivation on the growth, yield and quality of cucumber fruit and on the physical parameters of the substrate. The greenhouse cucumber cultivar ‘Mewa F1’ with semi-long fruits and smooth skin was used for the study. The plants were grown in the ‘Carbomat’ lignite substrate and ‘Grotop Master’ rockwool in two cycles. In cycle 1, new growing mats were used, while in cycle 2 the same growing mats as in cycle 1 were used again. In the hydroponic cultivation carried out on mineral wool and in the lignite substrate, both in the new and the reused substrate, the cucumber obtained mostly similar plant growth parameters and fruit color. Cucumber grown on the new mineral wool had a higher number and weight of fruits, which were characterized by a higher content of β-carotene and lutein compared to fruits from plants grown in the new lignite substrate. On the other hand, the reused lignite substrate resulted in higher cucumber yields and fruits with higher firmness and higher carotenoid content compared to cucumber grown on reused mineral wool. At the same time, the content of dry matter and sugar extract in fruits obtained from plants growing in the new and reused lignite substrate was higher compared to fruits grown in mineral wool. Both new and reused lignite substrate were characterized by very low plant-available water content. In contrast; the air and water holding capacity of lignite after cultivation did not change as much as that of mineral wool.

Response of Plant Rhizosphere Microenvironment to Water Management in Soil- and Substrate-Based Controlled Environment Agriculture (CEA) Systems: A Review

“…The physical properties of these materials are varied, and such discrepancies give a great scope for using multiple components for combination. Wider ranges of properties, such as volumetric density (30-1,400 kg•m −3 ), porosity (45-99% vol), water-holding capacity (-10 cm H 2 O, 15-85% vol), and air-holding capacity (-10-cm H 2 O, 20-80% vol), can also be obtained to adapt to a particular planting pattern (Lazny et al, 2021).…”

Low Plant Density Improves Fruit Quality without Affecting Yield of Cucumber in Different Cultivation Periods in Greenhouse

“…With the rapid development of the economy and living standards greatly improving, more and more people are considering fruit quality rather than cucumber yield [4][5][6].…”

“…Another means of cultivation in greenhouses is to grow cucumbers on mineral wool and irrigate them with inorganic nutrient solution. Although the composition of the nutrient solution remains the same, there are still differences in the quality of cucumbers in different cycles [6], under different CO 2 concentrations [11] and under different solution pHs [12].…”

Lignite Substrate and EC Modulates Positive Eustress in Cucumber at Hydroponic Cultivation

“…However, producing 1 m 3 of this substrate emits 167 kg of CO 2 into the environment and consumes 275 kWh [17], where the CO 2 emitted during transportation of the substrate to the customer and the disposal of stone wool waste after the production process are not taken into account. These problems have led to a search for alternative organic substrates that will reduce the use of mineral wool in hydroponic production [18,20,21]. For comparison, the CO 2 emitted during the production of 1m 3 of lignite is about 63 kg of CO 2 , which allows to reduce the emitted CO 2 by almost 40%.…”

“…For comparison, the CO 2 emitted during the production of 1m 3 of lignite is about 63 kg of CO 2 , which allows to reduce the emitted CO 2 by almost 40%. Calculations based on the life cycle assessment (LCA) methodology [22,23] A fully biodegradable substrate that has comparable physical properties to mineral wool is lignite substrate [20], which can be used as an organic fertilizer in conventional crops after the production process. Using such substrate instead of mineral wool could help reduce the carbon footprint.…”