Response of geranium to soil applications of Azolla and Moringa extracts: effects on growth, essential oil and physiological parameters

Abstract Background Geranium ( Pelargonium graveolens L.) is an important aromatic plant valued for its essential oil; however, its cultivation in sandy soils is often constrained by poor fertility and limited water-holding capacity. Therefore, this study was conducted to evaluate the effects of Azolla and Moringa extracts on growth, essential oil and physiological traits of geranium grown under sandy soil conditions. Methods Azolla extract at concentrations of 50 and 75% and Moringa extract at 5 and 10% were supplied through irrigation water throughout the growing season, and the plants were harvested on two occasions. Data were statistically analyzed using 2 ways analysis of variance (ANOVA-2). Results Obtained results demonstrated that both extracts enhanced morphological and physiological characteristics relative to the control treatment. Application of 10% Moringa extract produced the greatest improvement in all measured parameters compared with the untreated control: Plant height, branch number, and biomass (fresh and dry) increased by 2.5–2.6 fold, 2.1–2.3 fold and 2 -2.1 fold, respectively. Chlorophyll a , chlorophyll b and carotenoid increased by 1.7 fold, 2 fold and 1-1.3 fold, respectively. Essential oil content (%) and essential oil yield increased by 1.1–1.4 fold and 1.4–2.3 fold, respectively. Essential oil major components (citronellol, geraniol and α-gurjunene) and its major group (oxygenated monoterpene) increased by 2.4, 3.3, 2.7 and 2.3 fold, respectively. Phenols, flavonoids, inhibition of free radical, carbohydrate and crude protein increased by 1.5–1.6 fold, 1.6–1.9 fold, 1.7–1.8 fold, 2.3 fold and 1.5–1.8 fold, respectively. N, P and K content improved by 1.5–1.8 fold, 2.5 fold and 1.5–1.7 fold, respectively. N, P and K uptake increased by 3.1–3.6 fold, 5–25 folds and 2.9–3.3 fold, respectively. Conclusion Overall, the application of Azolla or Moringa extracts proved to be an effective and environmentally friendly strategy for improving geranium performance and essential oil production in sandy soils. These natural biostimulants offer a sustainable alternative to synthetic inputs and may support the commercial cultivation of geranium in newly reclaimed and desert lands.