Root activity measured by triphenyl tetrazolium chloride (TTC) is related to the aerobic respiration of root. Root aeration brings about effective nutrients absorption at the root for growth and yield of crops. Moreso, TTC activities in the roots is associated with dehydrogenase activity of tri carboxylic acid (TCA) cycle that regulate sugar (Carbohydrate) and mineral absorption in the plants. Atkins (1992) and Clark et al., (1992) revealed that PGR-IV a plant growth regulator which consists of gibberellic acid (GA3) and synthetic indole butyric acid (IBA) increased root mass and root activity of cotton plants. Cotton root activity measured by 2, 3, 5-triphenyl tetrazolium chloride reduction is also temperature dependent. It has been suggested that optimum temperature range of 33 to 36o C (Arndt 1945; Pearson 1970) could support growth and yield of cotton. The differences in optimum temperature are related to changes in stored seed reserves for cotton root growth (McMicheal and Burke 1994).