Theories Governing Crop Adaptation and Distribution
Theory of tolerance – Each plant or living organisms is able to thrive well in certain climatic conditions below which and above which the plant can’t grow, i.e., it requires optimum climatic conditions. Temperature is one of the most common limiting factors in plant distribution. Many tropical crops such as rubber, cocoa, banana will not with stand freezing temperature (0°C). In these rubber probably has the narrowest tolerance range and banana the widest range for temperature tolerance.
Theory of avoidance – It may be accomplished through rapid completion of the life cycle, as in ephemerals, dormancy in seeds to avoid effects of the hottest and driest periods, dormancy in vegetative parts or roots of all the perennials, water accumulation in succulents and extremely deep root systems to avoid moisture deficiency.
Theory of factors replaceability – One factor that can be replaced by another or substituted by another. For e.g.,
• Elevation can be substituted for latitude because of its temperature effects. The climatic conditions at the latitudes of 35–45° N resembles to that of tropical regions at elevation of 4000–6000 ft.
• The angle direction of slope may be substituted for latitude. This is also a temperature adjustment, depending on the angle of exposure to solar radiation, wind etc.
• Parent materials may compensate for climate.
• Rainfall may be replaced by fog and to some extent by dew.
• Soil texture may be substituted for moisture.
- Basics of Silviculture
- Agriculture History of India
- Silvicultural System of Concentrated Regeneration
- Coppice System of Silviculture
- Branches of Horticulture