Effect of Environmental Parameters on Plant Growth and Development and Application of Sensors
Plant growth and development are strongly influenced by environmental factors such as temperature, humidity, light, CO₂ concentration, soil moisture, pH, and nutrient availability. In protected cultivation and precision agriculture, these parameters must be monitored and controlled accurately. Modern sensors play a key role in providing real-time data for decision-making.
Key Environmental Parameters and Their Effects
A. Temperature
a. Effect on Growth:
- Influences seed germination, enzyme activity, photosynthesis, respiration, and flowering.
- Extreme heat → wilting, flower drop, pollen sterility.
- Low temperature → delayed germination, slow growth, chilling injury.
b. Sensors Used:
- Thermistors, thermocouples, infrared thermometers.
- Data used in climate control systems for heating/cooling of greenhouses.
B. Relative Humidity
a. Effect on Growth:
- High RH → favors fungal diseases (powdery mildew, Botrytis).
- Low RH → excessive transpiration, leaf drying.
- Optimal RH (60–70%) ensures good stomatal function and nutrient uptake.
b. Sensors Used:
- Hygrometers, capacitive humidity sensors.
- Used to regulate misting, fogging, or ventilation in greenhouses.
C. Light Intensity and Quality
a. Effect on Growth:
- Light drives photosynthesis and biomass production.
- Red and blue wavelengths regulate stem elongation, flowering, and chlorophyll synthesis.
- Low light → spindly growth, poor fruit set.
b. Sensors Used:
- PAR (Photosynthetically Active Radiation) sensors.
- Lux meters, quantum sensors, multispectral sensors.
- Used for controlling artificial lighting systems (LEDs in protected cultivation).
D. Carbon Dioxide (CO₂) Concentration
a. Effect on Growth:
- Higher CO₂ (600–1000 ppm) enhances photosynthesis and yields.
- Low CO₂ inside greenhouse → reduced growth due to plant consumption.
b. Sensors Used:
- Infrared gas analyzers (IRGA).
- CO₂ sensors integrated into automated ventilation and CO₂ enrichment systems.
E. Soil Moisture
a. Effect on Growth:
- Adequate soil moisture → proper nutrient transport and cell expansion.
- Deficiency → drought stress, reduced growth, flower abortion.
- Excess → root diseases (Pythium, Phytophthora).
b. Sensors Used:
- Tensiometers, FDR (capacitance probes), TDR sensors.
- Data applied for precision irrigation scheduling.
F. Soil Temperature
a. Effect on Growth:
- Affects seed germination, root growth, and microbial activity.
- Cold soils → poor nutrient uptake.
- Hot soils → root injury.
b. Sensors Used:
- Soil thermistors, digital soil temperature sensors.
G. Soil pH
a. Effect on Growth:
- Influences nutrient solubility and availability.
- Low pH (acidic) → Al and Mn toxicity, poor P availability.
- High pH (alkaline) → micronutrient deficiencies (Fe, Zn, Mn).
b. Sensors Used:
- pH probes, ISFET-based sensors.
- Used for fertigation and nutrient solution management.
H. Soil Electrical Conductivity (EC)
a. Effect on Growth:
- EC indicates total soluble salts (salinity).
- High EC → osmotic stress, nutrient imbalance, poor water uptake.
- Optimal EC range varies by crop (e.g., tomato 2.0–3.5 dS/m, cucumber 1.7–2.5 dS/m).
b. Sensors Used:
- EC meters, dielectric soil moisture-EC combined sensors.
- Used to manage fertilizer application and avoid salinity stress.
I. Wind and Air Circulation
a. Effect on Growth:
- Ensures uniform temperature, CO₂ distribution, and reduces humidity.
- Poor ventilation → disease outbreaks.
b. Sensors Used:
- Anemometers (wind speed sensors), air flow meters.
- Guide operation of exhaust fans and vents in greenhouses.