Abstract:
Ipomoea aquatica has been identified as a potential plant to phytoremediate nitrate
contamination of water. This study was conducted to select efficient treatments using Ipomoea
aquatica to reduce nitrates in groundwater ex-situ and to get adequate nitrate-safe leafy
vegetables. Groundwater samples were collected from a nitrate-contaminated well in the
Chunnakam aquifer and analyzed for nitrate content. The experiment was conducted in plastic
containers having 3.7 liters of groundwater in three-factor factorial design with three replicates,
in. The factors were numbers of plants (5/10), water refilling (without a refill/refill up to the
initial mark weekly), and foliar fertilizer application (without/with foliar fertilizer-FF). An organic
formulation containing banana pseudostem liquid and Panchagavya was used as a foliar fertilizer.
Treatments were, T1- 5 plants alone (PA), T2- 5 plants + FF, T3-10 PA, T4- 10 plants + FF, T5- 5
PA + refill, T6- 5 PA + refill + FF, T7- 10 PA + refill, T8- 10 plants + refill + FF. The pre-germinated
two weeks old seedlings of Ipomoea aquatica were placed in plastic net trays above the containers
having water in such a way that the roots were immersed in water. Nitrate in water was analyzed
initially and at weekly intervals. Fresh weight, dry weight and NO3
- - N (Nitrate Nitrogen) of plants
were measured after harvesting, at the end of three weeks after treatment. Initial nitrate in water
was 138 mg/L. The treatments with 10 plants removed significantly higher nitrate reaching the
safe level (below 50 mg/L). However, the available volume of water at the end was the lowest in
T3 and T4, while T7 and T8 had the initial volume, indicating the efficiency of refilling. The lowest
NO3
-
in treated water (23.46 mg/L) and the highest NO3
--N in plants (55.84 mg/kg) were recorded
in T8. According to the acceptable daily intake (ADI) limit of NO3
- - N as 3.7mg/kg body weight/per
day, this phyto-remediated Ipomoea aquatica could be used as a vegetable without any harmful
effect. It can be concluded that T7 (10 PA + refill) and T8 (10 plants + refill + FF) could be used by
households to treat nitrate polluted well water while getting fresh leafy vegetables.
