Evaluation the Effects of shade and Humic Acid on the Eco-Physiological Traits of Roselle (Hibiscus sabdariffa L.) under Different Irrigation Regimes

Roselle (Hibiscus sabdariffa L.) is important due to its versatility and multiple uses, ranging from food and beverages to traditional medicine and cosmetics. The field experiments were conducted at the research farm of Shahed University, and the Agricultural Jihad Department of Abyek City Research Station during ۲۰۱۷-۲۰۲۰. Roselle grew under ۰ and ۵۰% shade, three irrigation regimes (۲, ۴ and ۶ hours per week) and ۴ levels of humic acid (۰, ۳, ۶, and ۱۲ kg/ha) through a split-split experiment based on a randomized complete blocks design with ۳ replications. Measured parameters were plant height, stem diameter, number of flowering branches, sepal and capsule weight, number of fruits per plant, ۱۰۰۰-seed weight, plant dry weight, harvest index, fresh fruit length and diameter, inflorescence length, seed biological yield, flower protein (%), essential oil (%), anthocyanin (%), seed oil (%), and relative leaf water content. Results showed that shade treatments affected growth of roselle and significant differences in the most of above parameters were occurred.  The highest means of sepal, seed and biological yields were observed in combination of unshade with ۱۲ kg/ha humic acid application by ۸۳۶, ۱۸۱۷ and ۲۵۷۱۰ kg/ha respectively. Results indicated that, ۲ and ۴ hours irrigation reduced seed yield ۴۴ and ۴۹% and biological yield ۴۵ and ۴۸% respectively. Shading caused a notable decline of essential oil (۴۴%), anthocyanin (۷۱%), protein (۳۰.۵%), and oil content (۲۵%) compared to combinations of unshade and humic acid application treatment. In conclusion, this experiment demonstrated that shading and water deficiency had decreased the morphological traits and biological yield of the roselle plant, and applying humic acid in these conditions mitigated the adverse impacts of the stressors.

کلیدواژه ها:

Roselle ، shade ، humic acid ، Medicinal plants