Figures (5)  Tables (3)

    • Figure 1. 

      Spinach plants were grown in the indoor vertical NFT units with three levels and a reservoir tank. The plants at both ends of the channels were not counted due to low light intensity.

    • Figure 2. 

      Effects of bacterial endophytes on the growth of spinach cultivar 'Red Snapper' under indoor vertical farm conditions in NFT hydroponic systems. Bars with the same letters are not significantly different (p > 0.05). FW: fresh weight and DW: dry weight.

    • Figure 3. 

      Effects of bacterial endophytes on the growth of spinach cultivar 'Seaside' under indoor vertical farm conditions in NFT hydroponic systems. Bars with the same letters are not significantly different (p > 0.05). FW: fresh weight and DW: dry weight.

    • Figure 4. 

      Effects of bacterial inoculation on leaf greenness of spinach plants. Bars with the same letters are not significantly different (p > 0.05).

    • Figure 5. 

      Colonies of bacterial endophytes re-isolated from leaves of 'Seaside' at 18 d after inoculation of GFP-tagged bacteria. The images were taken under fluorescence microscope Olympus SZX12 with 5 s exposure and 11.2× magnification.

    • Dates
      (transplant to harvest)      		 No. of
      plants/treatment      		 Temperature
      (°C)      		 Light
      (h)      		 PPFD
      (μmol/m2/s)      		 DLI
      (mol/m2/d)      		 Relative humidity
      (%)
      29 Apr. – 19 May 2022 18 20.5 16 250 14.4 58.5
      4 Oct. – 27 Oct. 2022 36 21.0 16 250 14.4 55.5
      13 Sept. – 5 Oct. 2023 36 20.9 14 250 12.6 53.9

      Table 1. 

      Vertical NFT environmental conditions.

    • Plant growth
      promoting traitsa      		Pseudomonas
      psychrotolerans
      IALR632      		Enterobacter
      asburiae
      IALR1379
      Auxins (μg/mL)10.0 ± 2.9b56.8 ± 1.2
      N fixation++
      P solubilization (μg/mL)263.6 ± 12.4238.1 ± 18.2
      ACC deaminase++-
      Siderophore (%)97 ± 0.526 ± 5.3
      a Plant growth promoting traits were measured following previous publication[8]. b Data showed mean ± standard error.

      Table 2. 

      Plant growth promoting traits of bacterial endophytes.

    • Bacteria Cultivars Tissues Days after inoculation
      4 11 18
      IALR632 Red snapper Shoot 24.7 ± 8.5 209.4 ± 191.7 10.6 ± 9.1
      Root 2.7 ± 0.4 200.2 ± 197.7 0.6 ± 0.4
      Seaside Shoot 4.7 ± 3.4 2.3 ± 1.3 15.1 ± 8.1
      Root 17.1 ± 16.7 4.3 ± 1.5 1.7 ± 0.6
      IALR1379 Red snapper Shoot 4.9 ± 4.7 12.0 ± 6.0 5.0 ± 4.2
      Root 26.6 ± 26.4 841.7 ± 836.6 27.4 ± 8.7
      Seaside Shoot 7.8 ± 0.8 0.8 ± 0.5 6.9 ± 4.0
      Root 38.3 ± 3.1 6.8 ± 1.9 19.6 ± 5.2
      The values present averages of colonization form units (CFU) per mg fresh tissues from three biological replicates ± standard errors.

      Table 3. 

      Bacterial colonization of spinach seedlings using GFP-tagged bacterial endophytes.