Waste water irrigation in the regulation of soil properties, growth determinants, and heavy metal accumulation in different Brassica species.

To evaluate the impact of waste water (WW) irrigation, four Brassica species, namely B. campestris, B. juncea, B. napus, and B. nigra, were grown for 2 years in the agricultural field. First-year experiment (2014-2015) was conducted with the comparative effect of WW and ground water (GW) under a uniform dose of NPK (N80P45K45, kg ha-1). WW irrigation proved efficacious over GW to increase growth, physiological, and yield parameters. Increase in all parameters was due to the use of WW which leads to the improvement in the physico-chemical properties of soil as compared to resulted soil from GW application. Second-year experiment (2015-2016) therefore deals with WW irrigation only but under interaction with two levels of NPK fertilizers (N80P45K45 and N60P30K30, kg ha-1). Results of this year revealed that maximum enhancement in growth, physiological, and yield parameters was observed at WW × N60P30K30 and the input of WW × N80P45K45 was not of benefit. WW × N60P30K30 treatment was beneficial also because, at this treatment level, the accumulation of Cr, Cu, Pb, Ni, and Cd in leaf and seed was comparatively lesser in amount than that of WW × N80P45K45. The study concluded even though the use of WW was applicable to save freshwater, enhance soil nutrient status, and make N, P, and K balance at their lower inputs, WW irrigation caused accumulation of heavy metals in all Brassica crops far above the safe limits during a quite longer irrigation time (70 days and 105 days after sowing (DAS)). However, WW was safe to use only up to 35 DAS. Therefore, the study suggested that there should be regular monitoring of heavy metal concentrations in irrigation water as well as in various crop vegetables.

Interactive effect of potassium and flyash: a soil conditioner on metal accumulation, physiological and biochemical traits of mustard (Brassica juncea L.).

At present plants continuously bare to various environmental stresses due to the rapid climate change that adversely affects the growth and nutrient status of the soil and plant. Application of flyash (FA) in combination with potassium (K) fertilizer amendment improves soil physico-chemical characteristics, growth and yield of plants. Mustard grown in combination with FA (0, 20, 40 or 60 t ha-1) and K (0, 30 or 60 kg ha-1) treated soil was used to evaluate the effect on heavy metals (Cd, Cr and Pb) concentration and antioxidant system. The experiment was conducted in a net house of the Department of Botany, Aligarh Muslim University, Aligarh. Sampling was done at 70 DAS. The results showed that concentration of metals was found maximum in roots than the leaf and seeds. FA60 accompanied by K30 and K60 cause oxidative stress through lipid peroxidation and showed reduced levels of photosynthesis and enzymatic activity. Proline and ascorbate content increases with increasing flyash doses to combat stress. However, flyash at the rate of 40 t ha-1 together with K60 followed by K30 significantly boosted crop growth by enhancing antioxidant activity which plays a critical role in ameliorating the oxidative stress. Graphical abstract.