GA3 or PCPAA significantly increased stem length, internode length, dry weight of stem or leaves per plant, but slightly increased number of stem internodes.CCC significantly decreased stem length, internode length, dry weight of stem or leaves per plant but slightly decreased number of internodes.           Transverse sections in the uppermost internode of sorghum stem revealed that GA3 induced more thickening and lignification in cell walls of different tissues, increased the amount of phloem per vascular bundles, promoted cell elongation and radial enlargement of ground parenchyma cells. CCC treatment showed retardation in thickening and lignification of  vessels and peripheral mechanical tissue cell walls, maturation of ground tissue and elongation of ground tissue parenchyma cells.PCPAA increased the size of vascular bundle due to adnation of two  adjacent bundles, or to the increase in the amount of vascular tissues of the individual bundle, and promoted cell elongation of the ground parenchyma.                  GA3 and PCPAA promoted protein synthesis while CCC inhibited it in the two cultivars. GA3, PCPAA and CCC decreased total carbohydrates and crude fibers in grains of the two cultivars. Effect of growth regulators on ash percentage in sorghum grains varied to some extent according to cultivar and growth regulator used.