Agro-physiological and biochemical responses of Sorghum bicolor in soil amended by olive mill wastewater

Abstract

Produced in huge quantities, olive mill wastewater (OMW) causes serious environmental problems in the Mediterranean basin, where olive growing is concentrated.The purpose of this study has been to evaluate the short term effects of various OMW quantities application on several Sorghum bicolor agro-physiological and biochemical parameters as well as the effects on the main properties of the amended soils. Four doses of OMW (25, 50, 75 and 100 m³ haˉ¹) have been applied in comparison to control soil not treated with OMW.Results have showed an improvement of the organic matter, total nitrogen and minerals contents in soils treated with OMW proportionally to the increase of the doses applied. Moreover, soils microbiological activities have been strongly enhanced in comparison with control soil. Furthermore, the study of the effects of OMW on the Sorghum bicolor seeds germination has showed that raw OMW has blocked germination seeds. However, various effects on Sorghum bicolor seeds germination have been observed for the OMW amended soils extracts related to quantities applied. An improvement of the main agro-physiological and biochemical parameters as stems height, stems thickness, leaves number, leaves circumferences’, roots lengths, plant productivity, proteins content and essential minerals elements rates for the plants growing in soil treated with 25 m3 ha−1 OMW dose has been reported. Nevertheless, clear inhibitions have been observed for the highest OMW doses applied as 75 and 100 m3 ha−1.