Introductory Crop Physiology (1+1)

Heat Stress

• Plant response of heat and their tolerance levels varies. Leaves may help the plant to avoid heat due to transpiration but the process is negligible.
• Majority of the plant species survives high temperature because of their internal built up. Some of the thermal algae, cacti and several other desert plants experience as high as 70oC and yet survive. High temperature tends to denature proteins and also heavy water loses. One of the attributes is increased enzyme production to compensate for the destruction.
• Some organisms, a rise in temperature shows down some process and when some compounds like ascorbic acid and other vitamins are added the process is restarted.
• In general plants which are temperature tolerant, possesses enzymes which are more stable to high temperature. Infact in these enzymes some of the isozymes develop to high temperature.
• In summary it can be stated that most of the plants are heat tolerant because they possess the capacity to produce heat stable proteins. They also have the ability of replace thermal denatured protein immediately.

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