Abstract
Seedlings of Chrysalidocarpus lutescens, Dracaena deremensis and Dracaena marginata were grown in plastic containers filled with sphagnum peat-moss to assess the effects of three different water systems on plant growth, water saving and nutrient removal during the experimental period. The experiment lasted for 8 weeks and consisted of three water systems. These consisted of an open draining system fertigated with a standard nutrient solution (system T0) and two closed systems: sequential reuse of the leachate (system T1) and sequential reuse of the leachate with the addition of H2O2 (system T2). Over the course of the experiment, samples of water and supplies generated in each water treatment were collected weekly, and from these data water volume and nutrient loads were calculated. The addition of H2O2 to the leachate resulted in an enhancement in plant dry weight in Dracaena deremensis and Dracaena marginata. Regarding anion loads (Cl−, NO3−, H2PO4−, SO42−) in these water systems, there was a removal rate of 42%, 28%, 27% and 28%, respectively, in the closed systems compared to the open system. For the cation loads (Na+, K+, Ca2+ and Mg2+) in these water systems, there was a removal rate from 28% to 29%, respectively, in the closed systems compared to the open system.
Highlights
The increasing surface of greenhouses in Southern Europe and the Mediterranean region has led to several side effects such as environmental pollution, mainly associated with the release of water and nutrients as wastewater into the environment [1,2]
Fertigation of D. deremensis and D. marginata with T1 resulted in a decline of 13% and 20% in DW, respectively, compared to the control treatment (T0), whereas the fertigation of these species with T2 resulted in a significant increase of 16% and 18% in DW, respectively, compared to T0 (Table 2)
The results obtained show that fertigation with the sequential reuse treatment resulted in a clear reduction in the dry weights of D. deremensis and D. marginata plants
Summary
The increasing surface of greenhouses in Southern Europe and the Mediterranean region has led to several side effects such as environmental pollution, mainly associated with the release of water and nutrients as wastewater into the environment [1,2] This has become even more aggravated, since the majority of soilless cropping systems in the greenhouses in this area are open or free draining—draining the leachate directly into the soil [3,4]. Reduced yields associated with the increase in salinity in the root zone, and the risk of pathogen propagation throughout the fertigation system, entail more drawbacks for its implementation [11,12] Another management strategy for reusing the drainage and reducing the pollution generated is the sequential reuse of the leachate to irrigate increasingly salt-tolerant crops [13]. It is worth mentioning that in this fertigation system, each subsequent crop must be able to tolerate the accumulated salts from the previous crop in order to avoid plant damage and death [15]
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