Cumulative role of bioinoculants on growth, antioxidant potential and artemisinin content in Artemisia annua L. under organic field conditions

Artemisia annua L. is mostly known for a bioactive metabolite, artemisinin, an effective sesquiterpene lactone used against malaria without any reputed cases of resistance. In this experiment, bioinoculants viz., Streptomyces sp. MTN14, Bacillus megaterium MTN2RP and Trichoderma harzianum Thu were applied as growth promoting substances to exploit full genetic potential of crops in terms of growth, yield, nutrient uptake and particularly artemisinin content. Further, multi-use of the bioinoculants singly and in combinations for the enhancement of antioxidant potential and therapeutic value was also undertaken which to our knowledge has never been investigated in context with microbial application. The results demonstrated that a significant (P < 0.05) increase in growth, nutrient uptake, total phenolic, flavonoid, free radical scavenging activity, ferric reducing antioxidant power, reducing power and total antioxidant capacity were observed in the A. annua treated with a combination of bioinoculants in comparison to control. Most importantly, an increase in artemisinin content and yield by 34 and 72 % respectively in the treatment having all the three microbes was observed. These results were further authenticated by the PCA analysis which showed positive correlation between plant macronutrients and antioxidant content with plant growth and artemisinin yield of A. annua. The present study thus highlights a possible new application of compatible bioinoculants for enhancing the growth along with antioxidant and therapeutic value of A. annua.