Research Summary
This research establishes that sensor-based irrigation (maintaining 0.40 m³·m⁻³ volumetric water content) combined with a 'pick-and-eat' harvest strategy maximizes the yield, physiological stability, and palatability of Romaine lettuce grown in coarse-textured media (Turface). While sensor-based systems significantly improved photosynthesis and mineral uptake (P, K, and Mg), the study found they also promoted rhizosphere salinity buildup in 'cut-and-sow' systems due to a lack of leaching. Conversely, traditional time-based irrigation induced drought stress and premature bolting, which increased leaf calcium via lignification but reduced sensory scores for flavor and overall acceptability below the threshold for consumption.
Data & Results
### Table 1. NO3-N Concentration and Electrical Conductivity (EC) of Leachate
| Treatment Irrigation | Harvest Technique | NO3-N (40 DAS) | NO3-N (65 DAS) | NO3-N (78 DAS) | EC (40 DAS) | EC (65 DAS) | EC (78 DAS) |
|---|---|---|---|---|---|---|---|
| Sensor-based | PE | 150.50 | 122.00 | 23.50 | 0.79 | 0.53 | 0.46 |
| Sensor-based | CS | 146.00 | 370.00 | 97.25 | 0.75 | 1.54 | 1.17 |
| Sensor-based | Control | 807.50 | 987.50 | 402.50 | 3.29 | 3.59 | 3.10 |
| Time-based | PE | 92.75 | 79.17 | 21.50 | 0.88 | 0.52 | 0.44 |
| Time-based | CS | 27.25 | 108.23 | 16.25 | 0.43 | 0.56 | 0.40 |
| Time-based | Control | 104.00 | 97.11 | 33.67 | 0.61 | 0.57 | 0.53 |
### Table 2. Lettuce Physiological Responses
| Treatment | Harvest | Photo. (40 DAS) | Photo. (78 DAS) | Stomatal (40 DAS) | Stomatal (78 DAS) | Transp. (40 DAS) | Transp. (78 DAS) |
|---|---|---|---|---|---|---|---|
| Sensor-based | PE | 23.51 | 15.66 | 0.30 | 0.42 | 6.64 | 7.55 |
| Sensor-based | CS | 24.22 | 8.97 | 0.26 | 0.083 | 5.69 | 1.58 |
| Time-based | PE | 11.54 | 9.72 | 0.08 | 0.11 | 1.81 | 1.81 |
| Time-based | CS | 16.54 | 18.67 | 0.11 | 0.29 | 2.52 | 4.93 |
### Table 3. Growth and Yield Parameters
| Treatment | Harvest | Fresh Wt (Cumulative) | Dry Wt (Cumulative) | Leaf Area (Cumulative) | Root Dry Wt (78 DAS) |
|---|---|---|---|---|---|
| Sensor-based | PE | 220.41 g | 21.38 g | 4214.13 cm² | 4.69 g |
| Sensor-based | CS | 74.98 g | 6.54 g | 1648.72 cm² | 0.19 g |
| Time-based | PE | 121.77 g | 15.42 g | 3191.45 cm² | 9.12 g |
| Time-based | CS | 57.91 g | 5.95 g | 1143.62 cm² | 0.32 g |
### Table 4. Leaf Mineral Content (Pick-and-Eat Technique)
| Irrigation | Harvest | N (%) | P (%) | K (%) | Mg (%) | Ca (%) | S (%) | Na (%) |
|---|---|---|---|---|---|---|---|---|
| Sensor-based | 78 DAS | 4.15 | 0.46 | 3.33 | 0.57 | 0.54 | 0.36 | 0.12 |
| Time-based | 78 DAS | 4.03 | 0.32 | 3.09 | 0.56 | 0.76 | 0.41 | 0.08 |
### Table 5. Sensory Test Analysis Summary
| Treatment | Overall Acceptability | Appearance | Flavor | Mouthfeel |
|---|---|---|---|---|
| Sensor-based PE | 6.70 | 7.00 | 6.67 | 7.11 |
| Sensor-based CS | 6.40 | 6.06 | 6.67 | 6.44 |
| Time-based PE | 5.10 | 6.56 | 4.67 | 6.33 |
| Time-based CS | 8.00 | 7.83 | 7.83 | 7.17 |
Figures & Charts
- Figure 1: Demonstrates temporal fluctuations in volumetric water content (VWC) and bulk electrical conductivity (EC), highlighting that sensor-based systems maintain a consistent moisture setpoint while time-based irrigation leads to daily water stress cycles and higher salt leaching.
- Figure 2: Visually compares the morphological development of lettuce at 36 and 72 days after sowing, illustrating the enhanced biomass in sensor-based treatments and the physical evidence of premature bolting in time-based pick-and-eat plants.
Machine-Readable Metadata for AI crawlers
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