What are Growth Factors?

External growth factors are components which influence the growth of plants from outside the plant body.

(i). Biotic Growth Factors: biotic factor which influences the plant growth from external sides are just interaction of plants to other plants and competition among themself for the survival of them. These are managed by certain behaviors namely;

Mutualism, Herbivory, Parasitism

a. Mutualism: the interaction between plants for their cooperative mechanism for survival and yielding benefit to each other.

Example: lichens

b. Herbivory: it is the nature of animals where it depends upon plants for survival. When excessive grazing tales place other organism inhabiting the same region has low survival rate.

c. Parasitism: interaction between two organisms where one benefits from the interaction others not and are deprived from nutrition making it hard to survival.

(ii). Abiotic Growth Factors: Factors which does not involve biologically but are essential for growth. Different factors that influence the plant growth are:

a. Climate: each plant has its suitable climate at which they grow well. The climatic factors include: Precipitation, Temperature, Humidity, Solar radiation, Wind velocity and Atmospheric gasses.

1. Precipitation: is of all forms such as Rain, Fog, Haze, Dew, Snow, etc., out of which rain fall is crucial in plant growth. Precipitation is completely dependent on the geography of a region. The slopes of Western Ghats receive high rainfall than the plains therefore considering the rainfall plantation crops are grown at the slopes of Western Ghats. Similarly drier regions support drought resistance plants such as sorghum, wheat, millet etc.,

2. Temperature: temperature is determined by the topography of the region. An ideal range for any plant is between 15° C and 38° C. But for the ideal plant growth each species is unique. The temperature also influences other body activity such as diffusion of the gasses, solubility of different materials, etc.,

3. Humidity: Humidity is the presence of water molecule n the form of water vapor. Higher the humidity lowers the rate of transpiration. Hence water accumulates causing decay of plants.

4. Solar Radiation – Light: Respiration is the process where the CO2 consumed to produce O2. This takes place by the process called photosynthesis. Incident of light is essential for synthesis of energy for plants survival. The radiation controlled the situation by determining the temperature of the region.

5. Atmospheric Gasses: in atmosphere the ratio of Carbon, Oxygen and Nitrogen must be balanced properly other wise imbalances can causes destruction to entire living system.

b. Edaphic Growth Factors: is noting but the specificities of soil for plant growth. The soil has several criteria namely: soil moisture, air, temperature, pH, mineral content, organic content and microorganism.

1. Moisture content makes the availability of nutrients to the plant easily attainable.

2. Soil Air provides aeration which removes any accumulation of undesirable gases, remove the dampness of the soil thereby providing an ideal environment which is free from infections.

3. Temperature, affects the physico chemical process taking place inside the soil and keeps the microbial activity under control and prevent microbial accumulation

4. Soil Organism, microbial growth is well associated with root nodules present in the plant where they fix atmospheric nitrogen to fulfil the nitrogen need for plants.

5. Other, factors associate well with the above factors provide an ideal internal environment for plant growth.