Background

As the human population increases there is more demand on crop production. Fertilisers provide elements used to ensure healthy plant growth, such as nitrogen, phosphorus, and potassium. Without fertilisers, yields of crops would be lower. However, fertilisers are non-selective leading to growth of all plants including weeds and excessive fertiliser use can cause pollution, e.g. to water supplies and increased N2O emissions.

Plant hormones are also used in crop production to enhance productivity. They include gibberellic acid (GA), abscisic acid (ABA), cytokinin, ethylene and brassinosteroids, which regulate many aspects of plant growth and development at relatively low concentrations. GA promotes important processes in plant growth and development such as seed germination, cell elongation and cell division, as well as