Simultaneous use of irradiated sodium alginate and nitrogen and phosphorus fertilizers enhance growth, biomass and artemisinin biosynthesis in Artemisia annua L.

Marine polysaccharides (sodium alginate, carrageenan, chitosan, etc.) have proved as growth promoting substances in their depolymerized form for a number of medicinal and agricultural plants. Antimalarial drug, artemisinin, extracted from the leafy tissue of Artemisia annua L., is an effective and safe alternative remedy against malaria; it has proved effective against the highly adaptable malaria parasite. In order to increase plant growth and artemisinin content, field experiment was conducted for two consecutive years, using foliar application of an aqueous solution of gamma-ray irradiated sodium alginate along with split application of nitrogen and phosphorus fertilizers. Crop performance was assessed at pre-flowering and flowering stage in terms of growth, physiological and biochemical parameters and production of artemisinin in A. annua. Foliar application of 80 mg L−1 of irradiated sodium alginate (ISA) along with split application of nitrogen (40 + 40 kg N ha−1) and phosphorus (20 + 20 kg P ha−1) (i.e. ISA80 + N40 + 40 + P20 + 20) proved the best integrated treatment that gave maximal values for the attributes studied at flowering stage. As compared with the control, effect of this treatment (ISA80 + N40 + 40 + P20 + 20) was positive on dry leaf yield, leaf artemisinin concentration and artemisinin yield. The combined treatment enhanced the content and yield of artemisinin by 43.3 and 87.9%, respectively.