Effect of wastewater on physiological, morphological and biochemical levels and its cytotoxic potential on Pisum sativum

To meet burgeoning demand for water (mostly from agriculture), reclaimed wastewater is being reused, yet the environmental and health concerns about the effects of using raw and partially treated wastewater pose a challenge. Accordingly, here the effects of untreated wastewater on the pea plant (Pisum sativum) were examined in a holistic manner, by analyzing its morphological, physiological, and biochemical parameters. Wastewater samples were collected from Agra Canal, Faridabad, India at its most contaminated site. The tube-well samples were collected from village farmland located far from the canal. Sample analysis was carried out using standard available field and laboratory methods. Higher physicochemical parameters and concentrations of heavy metals were obtained for untreated canal wastewater (CW), nearly all being above the maximum permissible limit (MPL), whereas for tube-well water (TW) the same parameters are within the MPL. Pisum sativum seeds were treated with CW, TW, and Milli Q water (MQ, as control). When treated with CW, seeds had reduced germination and seedling growth was inhibited. Phytotoxicity parameters in CW-treated plants revealed oxidative stress and a significantly lower chlorophyll content than in TW- and MQ-treated plants. Likewise, significant reductions in the mitotic index and stomatal parameter values were observed. These findings indicate CW exerts toxic effects upon Pisum sativum grown in it. However, TW has a stimulatory effect on plant parameters, perhaps due to the dilution of toxic compounds like heavy metals. The present study suggests properly treated and diluted, CW may be used to irrigate crops as it also provides nutrients for plant growth, producing a stimulatory effect. Further investigation of heavy metal accumulation in different parts of plants irrigated with CW is required to evaluate its associated health risks.