ANTIOXIDANTS ACTIVITY IN STEVIA PLANT AS EFFECTED BY SHADING AND FOLIAR SPRAYING OF MORINGA AND LIQUORICE EXTRACT

Abstract

A field experiment was conducted in the fields of the College of Agricultural Engineering Sciences/University of Baghdad for the year 2021-2022 to study the effect of shading and the foliar application of some plant extracts on the growth, yield and natural antioxidants activity in the Stevia plant leaves. The experiment was conducted using a randomized complete block design (RCBD) using a split-plot arrangement with three replicates. The results showed that S₁ significantly outperformed the leaves' dry weight by 41.49 g plant^-1 and leaves' dry weight per hectare by 6.88 tons ha^-1. On the other hand, S₂ showed significant superiority in the total antioxidant activity by 11000.20 mg L^-1, total phenols by 9.947 mg L^-1, and leaves the chlorophyll b content by 76.16 mg 100 g^-1. Furthermore, M₂ significantly outperformed in the dry weight of the leaves with 38.21 g plant^-1, followed by G₂ with 36.30 g plant^-1.

Similarly, the dry weight of the leaves per hectare reached 6.33 tons ha^-1 in the M₂, followed by G₂ with 6.13 tons ha^-1. G₂ also excelled in total antioxidant activity with 12852.50 mg L^-1, while M₁ showed significant superiority in total phenols with 16135 mg L^-1. M₁ also showed a higher chlorophyll concentration with 189.45 mg 100 g^-1, followed by G₁ with 188.55 mg 100 g^-1 and M2 with 180.50 mg 100 g^-1. The liquorice extract (G₂) exhibited the highest overall antioxidant activity and chlorophyll b when interacting with shaded plants. Additionally, the Moringa extract (M₁) contributed to a significant increase in total phenols in shady Stevia plants.