## 2 Materials and Methods
### Irrigation and Mycorrhizal Treatment  
The substrate water content (SWC) of the air-dried substrate (%) was determined by the gravimetric method since the air-dried substrate contains hygroscopic moisture, that is, a certain amount of water that should be considered when determining the irrigation rate. The SWC was determined by weighing 100 g of air-dried substrate, which constitutes the weight of the wet sample. The sample of air-dried substrate was dried in a dryer in a paper bag at 70 \({}^{\circ}\)C, i.e., a lower temperature than usual (105 \({}^{\circ}\)C) due to the high content of organic matter. After a constant weight is reached, the sample of the dry substrate is weighed again, which gives the weight of the dry sample. Afterward, the SWC is determined by the gravimetric method according to [PERSON] et al. [63]:  
\[\text{SWC}=(\text{Swet}-\text{Sdry})/\text{Sdry}\times 100 \tag{1}\]  
The SWC represents substrate water content (%), Swet (g), and Sdry (g) is the weight of wet and dry substrate, respectively. The Hyprop (Hydraulic PROPerty analyzer, DecagonDevices, Inc., Pullman, WA, USA) instrument was used to develop a moisture release curve (Figure 1) that represents the relationship between the water potential and volumetric water content (%). The readily available water (RAW, 29.2%) or the amount of water that is easily extracted by the plants was determined as the difference between water retention capacity (\(-1\) to \(-5\) kPa, WRC, 62.3%) and refill point (\(-5\) to \(-10\) kPa, 33.1%). The irrigation rate corresponds to RAW which means that in this study, an irrigation rate of 0.29 L/pot is sufficient to fill the water content from the refill point to the WRC in the I\({}_{100}\) irrigation treatment. Consequently, the irrigation rate on I\({}_{80}\) and I\({}_{60}\) irrigation treatments was 0.18 and 0.14 L/pot, respectively. The irrigation rates were calculated to meet irrigation thresholds. Plants were watered with water from a well of satisfactory quality, i.e., without restrictions on use (Table 1). The well is 3 m away from the greenhouse and 20 m deep. Before watering, the water was previously aged to settle larger particles and to heat the water to an optimal 20-25 \({}^{\circ}\)C. The irrigation time was monitored by the AT sensor (Delta-T Devices Ltd., Cambridge, Great Britain) with substrate moisture output as volumetric water content (WVC, %). VWC was calculated using a calibration curve provided by a manufacturer for soilless peat-based substrates. Accordingly, the thresholds for irrigation events were 45% (I\({}_{100}\)), 38% (I\({}_{80}\)), and 30% (I\({}_{80}\)). Each container was irrigated by hand so that minimum drainage water occurred. The commercial mycorrhizal preparation used was Mykorrhiza Soluble ([PERSON], Innsbruck, Austria) and consisted of four species of endomycorrhizal fungi (_Glomus intranadices, Glomus moseae, Glomus aggregatum_, and _Glomus etunicatum_), five species of ectomycorrhizal fungi (_Pisolithus tinctorius, Rhizopogon villosulus, Rhizopogon lutteolus, Rhizopgon fuligleba_, and _Rhizopogon amylopogon_), and beneficial microorganism (_Bacillus subtilis_, _B. licheniformis, B. azotoformans, B. megaterium, B. coagulans, B. pumilus, B. thuringiensis, B. stearothermophilus, Paeinbacillus polymyxa, P. durum, P. fluorescens, P. gordonae, Azotobacter polymyxa, A. dicrooccum, Saccharomyces cerevisiae, Streptomyces griseus, S. Iydicus, Pseudomonas aureusforeaciens, Deinococcus erythromycinaya_). The acting mechanism of beneficial soil microorganisms in this study is assessed by promoting the functionality of MT. The mycorrhizal treatment was carried out by adding 1 tablespoon in 7 L o