Factors affecting the efficiency of growth of crops

Canopy characteristics

The canopy characteristics that are important for determining radiation interception are:

1. Leaf area index
2. Leaf area duration
3. The canopy Extinction coefficient(k)

• Leaf area index (LAI) is defined as the surface area of the leaf canopy per unit of ground area.
• The leaf area index at which 95% of the incident radiation is intercepted is often termed the critical leaf area index.

Photoperiod

• The influence of say length on plant growth is usually overshadowed by its conspicuous effect on flowering in many grasses and legumes.
• The reproductive phase is triggered by increasing day length ( decreasing nigh length) in some species, and by decreasing day length in others.
• The reproductive phase can also be triggered by a period of cold temperatures or a combination of day length and cold temperature.

Temperature

• It affects the rate of growth and development and can also determine the switch of plant development from one phase to other.
• The rate of plant processes such as photosynthesis, respiration and nutrient uptake are also dependent on the temperature.
• The dry matter yield of plant tops and roots of tropical grasses increases markedly with an increase in temperature to an optimum which lies between 30-35 degree Celsius.

Water

• Cell is more sensitive to water stress than in photosynthesis, so often the first measurable sign of water stress is smaller leaves due to decreased leaf elongation.
• Relative to leaf elongation, the rate of root elongation is greater during the mild water stress, resulting in the growth of roots being relatively greater than the growth of shoots.

Soil fertility

• High quality legumes such as alfalfa and ladino clover thrive only on the soils well supplied naturally or artificially with P, Ca, Mg and K.
• Similarly, grasses such as smooth brome grass, timothy, and cocksfoot grow well only if there is ample N in the soil.
• In the absence of adequate amounts of these elements, plants having lower requirements must be substituted.
• In general, plant growth rate is decreased by all nutrient deficiencies, and reproductive development and seed quality can also be affected.