Take Root Plant Hormones include IBA, IBA-K, NAA, NA-NAA etc. Take Root Plant Hormones mainly have th effect of promoting the root growth quickly. Plant hormones affect gene expressionand transcription levels, cellular division, and growth. Plant hormones are naturally produced within plants, though very similar chemicals are produced by fungi and bacteria that can also affect plant growth. A large number of related chemical compounds are synthesized by humans. Plant hormones are used to regulate the growth of cultivated plants, weeds, and in vitro-grown plants and plant cells; these manmade compounds are called plant growth regulators or PGRs for short.