Phytotoxic effects sewage water on growth, yield, physiological, biochemical and anatomical parameters of faba bean (Vicia faba L.)

Two pot experiments were conducted under greenhouse conditions to study the effect of sewage water on growth, leaves pigments, certain biochemical composition, yield and anatomical of faba bean plants. These experiments were performed in the Department of Agricultural Botany, Faculty of Agriculture, Kafrelsheikh University, during two successive seasons of 2013/2014 and 2014/2015. Faba bean (V. faba L.; cv. Sakha 1) was obtained from Food Legumes Research Section at Sakha Agriculture Research Station (SARS). The experiments were arranged in a factorial arrangement, with three levels of sewage water were diluted with tap water to give 25, 50 and 100% in addition to 0% used in irrigation. The main obtained results will be summarized as follows sewage water at 25% concentration significantly increased plant height, number of branches/plant, leaf area, dry weights of root and  shoot  while sewage water at 100% concentration significantly decreased the same characteristics at 60 and 75 days after sowing in both seasons compared with control plants. Maximum total number of flowers/plant was resulted from low concentration of sewage water (25%Sw). There are increases on the number of flowers at all days of flowering period after sowing compared with control plants in both seasons. There was a decrease for total number of flowers/plant from using (50%Sw) and (100%Sw). Application of sewage water in faba bean plants with low (25%Sw)concentration significantly increased number of pods/plant, number of seeds/pod, weight of 100 seeds g., and seed yield g /plant compared with control plants. While the highest concentration of sewage water (100%SW) significantly decreased above mentioned characters compared with control plants in both seasons. The treatment of sewage water (Sw 25%) significantly increased chl.a, chl. b, and total chl. compared with control plants. Chlorophyll pigment of faba bean leaves were decreased as sewage water concentration increased (100%Sw). Data also showed N, P and K percentages significantly increased in shoot under lower concentration of sewage water (Sw 25%) irrigation, while Zn and Fe concentration significantly decreased in shoot in both seasons compared with control plants. The highest concentration of (100% SW) gave significant decrease for N, P and K percentages in faba bean shoot, in the same time, this treatment caused significant increase for Zn and Fe percentages comparing to control plants. Heavy metals (Cd and Pb) in faba bean plant organs (root, shoot and seeds) significantly increased as increasing heavy metals concentration in sewage water content of heavy metals (Cd and Pb) was found in root followed by shoot and seeds. Using sewage water in irrigation faba bean plants at 25% and 50% concentration significantly increased protein and total carbohydrates content in seed in both seasons compared with control plants. Application of sewage water in at 100% concentration significantly decreased seed content of protein and total carbohydrates in both seasons compared with control plants. Anatomical characteristics measurements of faba bean root and stem were affected by all concentration of sewage water irrigation, sewage water at 100% gave the lowest values of diameter thickness of cortex tissue, diameter of xylem vessel, and these decreases were significant compared with the control. Analysis of fluorescence revealed lignin deposit in the Epidermis cells that was observed in the treatment exposed to the highest level of sewage water. abaxial epidermis of faba bean leaves showed slightly elongated cells irregular in shape with reduced size at the higher concentrations of sewage water treatment.