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.
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