*2.1. Effects on Germination of Cotton Seed*

Successful germination of seed and development of seedlings requires a good soil environment, especially soil moisture content and soil temperature. These requirements vary from plant species to species [17,18]. Generally, high temperature results in poor seed germination in field crops. The germination of seed is a complex physiological process that depends upon the activity of several cellular organelles and enzymes. These enzymes need to be produced in a continuous manner to perform various activities related to metabolic processes. For instance, in maize at high temperatures, these enzymes denature or slow down these activities, which results in reduced metabolism processes [19]. Moreover, high soil temperature also increases the rate of transpiration, which reduces the water availability to seed. Less availability of water also slows down the seed germination [20]. The optimal temperature of 28 to 30 ◦C is needed for germination of cotton seed. As the temperature decreases, the rate of seed germination also decreases, and very poor germination can be observed at temperatures <20 ◦C. Similarly, increases in temperature

from the optimal range (≥38 ◦C) have also been reported to result in decreased germination of cotton seed [21].

**Figure 1.** Salient adverse effects of high temperature stress on cotton plants.
