Some of the Factors that affect plant growth are :
•Water •Air/ Humidity •Light •Temperature •Nutrients
Water
- RO Water is used in Hydroponics
- It should not contain any harmful pathogen or chemicals
- It should be at right temperature and with slightly acidic pH for optimal plant growth.
- Hard water is not suitable as it has high mineral content with pH of Eight.
Air/ Humidity
- Oxygen and Carbon dioxide require for Respiration and Photosynthesis of plants.
- In an enclosed polyhouse, CO2 could be depleted early in the day & needs to be replaced by proper Ventelation & a sufficient number of air exchanges during day.
- 40%-50% of dry plant matter consist of carbon obtained from CO2 in air.
- Humidity plays a major role in transpiration of plant
- High humidity causes fungal growth.
Light
- Intensity of light influences the manufacture of plant food, length of stem, leaf color and flowering of plant.
- Plants grown in low light tend to be spindly in structure with light green leaves. A similar plant grown in very bright light tends to be shorter, better branches, and have larger, dark green leaves.
- Lettuce are Long day plants which require more than 12 hours of light.
Temperature
- In general, foliage plants grow best between 18 degrees and 26 degrees C during the day.
- Plants prefer nighttime temperatures range from 12 degrees to 16 degrees C. Lower nighttime temperatures help the plant: recover from moisture loss, intensify flower color and prolong flower life
- At low temperature – frost kill plants
- At high temperature – scorching occur at the margins of leaves.
Nutrients
- Macronutrients (C, H, O, P, K, N, S, Ca, Mg) – required in large amount by plants
- Micronutrients – required in less amount by plants
- Generally two types of solution used in Hydroponics:
1. Solution A 2. Solution B
- Nutrients in soltuion is measured by EC of solution
- Absorption of nutrients highly depends on pH of solution
- Most favourable pH for plants to absorb nutrition is 5.5 to 6.5