Plant Injury Due To Sudden Changes In Temperature

Living organisms receive and transfer thermal energy through radiation, conduction, and convection. Transpiring water to the surrounding atmosphere also transfers thermal energy from growing plants. Through these processes, they remain in equilibrium with the surrounding environment and maintain normal growth and development. However, with the passage of weather systems, changes in atmospheric temperature are often very sudden, and plants cannot adjust to these severe variations and are damaged beyond recovery.

Leaf Temperature versus Air Temperature

Under normal conditions, leaf temperature remains around the ambient temperature but differs under certain situations. At a temperature of about 33°C, there is a tendency for equality between air and leaf temperature. Below this temperature, leaves tend to be warmer than the air and vice versa.

TABLE 3.2. Temperature dependence of net photosynthesis during the growing season under conditions of natural carbon dioxide availability and light saturation

Temperature limits (°C) for carbon dioxide intake

Temperature limits (°C) for carbon dioxide intake

TABLE 3.2. Temperature dependence of net photosynthesis during the growing season under conditions of natural carbon dioxide availability and light saturation

Plant group

Lower limit

Optimum

Upper limit

C4 plants of hot habitats

-5 to 7

35 to 45

50 to 60

C3 crop plants

-2 to over 0

20 to 30

40 to 50

Alpine plants

-7 to -2

10 to 20

30 to 40

Evergreen tropical trees

0 to 5

25 to 30

45 to 50

Deciduous trees of tem

-3 to -1

15 to 25

40 to 45

perate zone

0 0

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