Fig 1.
Schematic diagram of the hydroponic indoor farming system used in this study.
Table 1.
Summary of cultivation condition, sampling time, and nutrient solution injection time.
Fig 2.
Changes in plant height, electric conductivity (EC), and number of fruits during tomato growth in a closed hydroponic system.
Vertical dashed lines indicate when new nutrient solution was added.
Fig 3.
Dynamics of nutrition uptake rates of macro nutrients and secondary nutrients during tomato growth in the closed hydroponic system.
Fig 4.
Variation in pH, EC, and major ions (NO3–-N, PO43–-P, Ca2+, SO42–, K+, Mg2+, Na+, and Cl–) during tomato growth in the closed hydroponic system.
Fig 5.
Variation in pH, EC, and minor ions (dissolved Fe, dissolved Mn, Cu2+, and Zn2+) during tomato growth in the closed hydroponic system.
Fig 6.
Comparison of ion concentrations determined by analytical instruments [i.e., cations by inductively coupled plasma-optical emission spectroscopy (ICP-OES), anions by ion chromatography (IC)] and on-site measurements [i.e., K+, Na+, Cl−by ion-specific electrodes (ISE) and NO3– and PO43– by commercial kit].
Fig 7.
Variation in the saturation index (SI) of several carbonate and phosphate minerals during tomato growth in the closed hydroponic system.
Vertical dashed lines indicate when new nutrient solution was added.
Fig 8.
X-ray diffractograms of the precipitates from nutrient solution.
Fig 9.
Scanning electron microscope (SEM) photos of the precipitates from nutrient solution.
‘c’ indicates amorphous clusters and ‘p’ indicates plates.