a) Soil temperature requirements of plants: The soil temperature requirements
of plants vary with the species. The temperature at which a plant thrives and
produces best growth is called optimum range (temperature). The entire range of
temperature under which a plant can grow including the optimum range is called
growth range. The maximum and minimum temperatures beyond which the plant
will die are called survival limits.
Range Maize (C) Wheat (C)
Optimum range 25 - 35 15 - 27
Growth range 10 - 39 5 - 35
Survival limits 0 - 43 0 - 43
b) Availability of soil water and plant nutrients: The free energy of water
increases with temperature. Up to wilting point limit, warming of soil increases
water availability beyond which it decreases. Low temperatures reduce the nutrient
availability, microbial activities and root growth and branching. The ability to
absorb nutrients and water by plants reduces at low temperatures.