Effects of wastewater quality on Henna (Lawsonia inermis L.) germination and seedling growth: a case study, Tunisia

Water resources scarcity led countries like Tunisia to adopt a policy of water economy by increasing the use of treated wastewater in agricultural irrigation. In this context, we studied the effects of raw and secondary treated urban and industrial waste waters and fresh waters (distilled and well waters used as control) on the germination and seedling growth of Lawsonia inermis. The seeds were used untreated or pretreated with 0.5% H2SO4, concentrated H2SO4 and soaked in distilled water prior to germination. Germination was conducted at 25°C during 7 days under conditions of dark and light. Germination rate, moisture content, root and shoot lengths were measured in different experimental conditions crossing seed pre-treatment, water quality and incubation condition. The R software was used to perform three classification factors ANOVA, Pearson correlation analysis and multiple linear regression analysis. Results showed that the best germination performance was obtained when the seeds were pretreated by 0.5% H2SO4, watered by treated urban wastewater and exposed to light. Treated urban wastewater had a best contribution to germination rate considered model than fresh water and the other wastewaters types tested. So at the stage of early growth treated urban wastewater could be considered as potent water for Lawsonia inermis irrigation.