Articles
Hydroponic and aeroponic cultivation of lettuce in urban green roof systems using either nutrient solution or greywater
Article number
1441_20
Pages
157 – 166
Language
English
Abstract
Green roof systems (GRS) are popular for the re-introduction of the urban lost flora.
However, their usage on building retrofitting is limited due to the additional weight exerted on the building framework.
The present study evaluated the use of lightweight hydroponic and aeroponic systems as GRS irrigated either with hydroponic solution or with greywater.
Fourteen outdoor high-tech lysimeters with internal dimension of 2×1 m were used to grow lettuce (Lactuca sativa ‘Cos Doris’ (Dover)) and treatments included: a) a hydroponic system with bags filled with agricultural perlite as growing medium; b) an aeroponic system using a polystyrene cap as container allowing the unrestricted development and mechanical support of the root system in the air; c) irrigation with modified Hoagland nutrient solution; and d) irrigation with greywater collected from a private house.
Each treatment was replicated 3 times (2 systems × 2 irrigation sources × 3 replications = 12 lysimeters). In each lysimeter, 18 lettuce plants were planted.
Four additional lysimeters served as unplanted irrigated controls and two empty lysimeters simulated a conventional rooftop, totalling 18 lysimeters.
Measurements were performed in 4 central plants within each lysimeter and included plant height and growth index, leaf stomatal conductance, SPAD, leaf fluorescence, pH, and EC of the effluent.
The weight fluctuation of each treatment was determined using weighing lysimeters equipped with load cells in conjunction with real time effluent volume determination using tipping buckets.
Weighing was averaged though a junction box and transmitted using Arduino while tipping bucket data were transmitted through PLC. Results show that the surface density of the aeroponic system was 5.4-8.3 kg m‑2, while that of the hydroponic system varied between 26.1 and 45 kg m‑2. Lettuce growth was promoted using hydroponic compared with the aeroponic system and greywater was proved to be inadequate for plant growth.
The growth results were supported by SPAD and leaf fluorescent and stomatal conductance measurements.
The drainage pH and EC for greywater (7.5-9.9 and 0.6-0.7 dS m‑1, respectively) and nutrient solution (5.8-7.0 and 1.7-1.8 dS m‑1) remained within the acceptable range for lettuce growth.
Based on the current study, the hydroponic system using modified Hoagland nutrient solution was the only acceptable treatment for lettuce growth.
However, their usage on building retrofitting is limited due to the additional weight exerted on the building framework.
The present study evaluated the use of lightweight hydroponic and aeroponic systems as GRS irrigated either with hydroponic solution or with greywater.
Fourteen outdoor high-tech lysimeters with internal dimension of 2×1 m were used to grow lettuce (Lactuca sativa ‘Cos Doris’ (Dover)) and treatments included: a) a hydroponic system with bags filled with agricultural perlite as growing medium; b) an aeroponic system using a polystyrene cap as container allowing the unrestricted development and mechanical support of the root system in the air; c) irrigation with modified Hoagland nutrient solution; and d) irrigation with greywater collected from a private house.
Each treatment was replicated 3 times (2 systems × 2 irrigation sources × 3 replications = 12 lysimeters). In each lysimeter, 18 lettuce plants were planted.
Four additional lysimeters served as unplanted irrigated controls and two empty lysimeters simulated a conventional rooftop, totalling 18 lysimeters.
Measurements were performed in 4 central plants within each lysimeter and included plant height and growth index, leaf stomatal conductance, SPAD, leaf fluorescence, pH, and EC of the effluent.
The weight fluctuation of each treatment was determined using weighing lysimeters equipped with load cells in conjunction with real time effluent volume determination using tipping buckets.
Weighing was averaged though a junction box and transmitted using Arduino while tipping bucket data were transmitted through PLC. Results show that the surface density of the aeroponic system was 5.4-8.3 kg m‑2, while that of the hydroponic system varied between 26.1 and 45 kg m‑2. Lettuce growth was promoted using hydroponic compared with the aeroponic system and greywater was proved to be inadequate for plant growth.
The growth results were supported by SPAD and leaf fluorescent and stomatal conductance measurements.
The drainage pH and EC for greywater (7.5-9.9 and 0.6-0.7 dS m‑1, respectively) and nutrient solution (5.8-7.0 and 1.7-1.8 dS m‑1) remained within the acceptable range for lettuce growth.
Based on the current study, the hydroponic system using modified Hoagland nutrient solution was the only acceptable treatment for lettuce growth.
Publication
Authors
I.N. Daliakopoulos, P.A. Nektarios, D. Harkoutsis, D. Paradimitriou, C. Daskalaki, N. Markakis, T. Manios
Keywords
adaptive green roof systems, Mediterranean zone, substrate depth, substrate type, native plant species, deficient irrigation, drought tolerance
Groups involved
- Division Landscape and Urban Horticulture
- Division Greenhouse and Indoor Production Horticulture
- Division Precision Horticulture and Engineering
- Division Plant-Environment Interactions in Field Systems
- Division Horticulture for Human Health
- Division Vegetables, Roots and Tubers
- Working Group Vertical Farming
- Working Group Urban Horticulture
Online Articles (36)