Fungitoxic activity and resistance induction in wheat plants against <em>Bipolaris sorokiniana</em> by <em>Artemisia camphorata</em>

Abstract

Aqueous extract (AE) from medicinal plant Artemisia camphorata (camphor) was used to evaluate the fungitoxic activity (by inhibition of mycelial growth, sporulation and conidia germination of the pathogen) and the resistance induction, aiming to promote alternative control of Bipolaris sorokiniana on wheat. AE in autoclaved or non-autoclaved concentrations of 1%, 5%, 10%, 15%, 20%, 25% and 50% was prepared with or without antioxidant (Na₂SO3 – 0.25%). To evaluate resistance induction, 30-day plants were sprayed with AE and 24, 48 and 72 hours after the treatments the leaves were inoculated with pathogen (1 x 10⁴ conidia/ml). 50% AE caused 39% of mycelial growth inhibition. 10% AE inhibited the fungus sporulation in vitro totally. Non-autoclaved AE inhibited only 20% of conidia germination but the autoclaved AE did not cause inhibition showing the presence of thermo-sensible compounds. The incorporation of antioxidant Na2SO3 in AE increased the inhibition of conidia germination. The camphor AE also induced systemic resistance in wheat plants, reducing the size (up to 29%) and number of spots (up to 60%). The induction was higher in plants treated with camphor 72 hours before the inoculation with pathogen. These results confirm the potential of camphor AE in alternative control of black point wheat.