OPERACIONES CON PERSONAS RELACIONADAS Y CONFLICTOS DE INTERÉS

Plant and substrate measurements made in each experiment are summarised in Table 2.3; methods and procedures for each of the measurements are outlined in Sections 2.5.1 - 2.5.6, with specific details of timings and replication for each experiment described in relevant chapters.

Table 2.3: Summary of the plant and substrate parameters measured in each experiment.

Parameter

Stormwater management Greywater Expt. 1 Expt. 2 Expt. 3 Expt. 4 Expt. 5 Expt. 6

Substrate moisture content (SMC)      

Substrate electrical conductivity (EC)  

Evapotranspiration (ET)     

Canopy size (height and diameter)      

Leaf area     

Root and shoot dry weights     

Plant visual health and quality  

Stomatal conductance to water vapour  

Canopy temperature  

43

2.5.1 Substrate moisture content and electrical conductivity

Substrate moisture content (SMC) was measured in all experiments using a WET sensor connected to a HH2 Moisture Meter (Delta-T Devices, Cambridge, UK). In Experiments 1, 4, 5 and 6 two measurements were made in each 2 L container, and in Experiments 2 and 3 five measurements were made per tray, on each measuring occasion. The WET sensor was calibrated for use with the MRM substrate by Delta-T Devices, and was used on the ‘organic’ substrate setting with the VC mix and peat-based compost.

For Experiments 5 and 6, substrate electrical conductivity (EC) and temperature data, measured by the WET sensor simultaneously with SMC, were also generated. Since EC is dependent on temperature, all EC readings were corrected after measurement by manually applying a temperature compensation coefficient of 2% per °C: all EC values are thus reported at 25°C. A temperature correction coefficient of 2% °C-1 _{was chosen as it is recommended as the default}

value by the WET sensor manufacturers, Delta-T Devices, for reporting EC at a standard temperature, and represents an average correction value for a range of substrate solutions.

2.5.2 Evapotranspiration

Evapotranspiration (ET) from all treatments was measured in Experiments 1, 2, 3, 4 and 6. Containers/trays were weighed every 24 hours using a CBK 32 bench checkweighing scale (Adam Equipment Ltd., Milton Keynes, UK) and daily ET was estimated as the weight loss per container/tray between two consecutive measurements. This was converted to ET depth (in mm) using Equation 1.1 (Section 1.3.5) by dividing the weight loss by the plot area.

2.5.3 Plant/canopy size and biomass

Several parameters were measured in all experiments to characterise canopy size. Plant/canopy height (measured from the substrate surface to the top of the tallest stem) and diameter (the average of two perpendicular measurements taken from above) were measured in all experiments. Leaf area was measured in Experiments 1, 2, 3, 4 and 6 using a leaf area meter with associated WinDIAS 3 Image Analysis System (Delta-T Devices, Cambridge, UK). In Experiments 1, 2, 4 and 6 all leaves from each plant/canopy were removed and their area measured. In Experiment 3, leaves were collected from a representative section of each tray (15 x 36 cm) and the measured leaf area was then scaled to tray size to give an estimate of the full canopy area. Additionally, in Experiment 3, leaf area density (i.e. cm2 _{leaf area per cm}3 _{of canopy) was}

44 Plants were harvested for biomass measurements in Experiments 2 – 6. Shoots and roots were separated and roots were carefully washed, removing as much substrate as possible. Shoots and roots were then dried in a ventilated oven at 70 ° C for 72 hours before being weighed with a Kern PCB 250-3 precision balance (Kern & Sohn, Balingen, Germany). In Experiment 3, roots and shoots from a representative area of each tray were harvested and results scaled up to describe the full canopy biomass. Additionally, fresh root volume was obtained in Experiment 3 by measuring the water displacement when roots were submerged in water in a measuring cylinder.

2.5.4 Plant health

Plant visual health was assessed throughout Experiments 5 and 6. Each plant was scored using a rating scale from 0 to 5 based on the visual plant health assessment system used by Sharvelle et

al. (2012). Additionally, the number of dead leaves per plant was counted in both experiments

(excluding Sedum in Experiment 6 due to counting difficulties), and total leaf numbers were also counted for Salvia, Stachys and Heuchera. Dead leaves were removed from all plants after counting in Weeks 4 and 6 in Experiment 5 and after every counting in Experiment 6 to enable easier counting and to make irrigation easier.

2.5.5 Leaf stomatal conductance to water vapour

Leaf stomatal conductance to water vapour (gs) was measured during Experiments 5 and 6. Measurements were made at approximately the same time of day for each species using two young, fully expanded leaves on each plant. Measurements were made on one plant from each treatment alternately to account for any changes in environmental conditions throughout the day that might cause differences between treatments.

For Heuchera, Salvia, and Stachys, gs was measured using an LCpro-SD infrared gas analyser (IRGA; ADC BioScientific Ltd., Hoddesdon, UK) with photosynthetic photon flux density supplemented to 1400 μmol m-2 _s-1_{using an external light source to ensure constant light levels}

throughout. When leaf sizes were too small to fill the whole chamber, approximate percentage coverage was visually estimated and gs results were subsequently corrected during data analysis to give approximate gs for 100% coverage. Owing to the very small leaf size of Sedum, an AP4 porometer (Delta-T Devices, Cambridge, UK) was used to measure gs.

Although ideally the same equipment would have been used to measure the gs all species, Sedum leaves were too small and too densely arranged to fit in the IRGA chamber, and the porometer was unsuitable for use with Salvia and Stachys as the humidity retained within the boundary layer

45 of their hairy leaves resulted in inconsistent and unreliable readings. However, since the objective of this study was gs comparison within rather than between species, the decision was made to use the porometer for Sedum and the IRGA for the broadleaf species.

2.5.6 Canopy temperature

In Experiments 5 and 6, canopy temperature was inferred from thermal images taken with an infrared imaging camera Thermo Tracer TH7800 (NEC San-ei Instruments Ltd., Tokyo, Japan). Plants were always positioned in the shade for at least 10 minutes prior to image taking to avoid sunlight variations; images of all plants were taken within one hour from the same distance and angle. Images were then analysed using NS9200 Report Generator software (NEC San-ei Instruments Ltd., Tokyo, Japan); canopy temperatures were determined in three representative areas for each plant and averaged to give a whole canopy temperature.