Role of hydroxyl benzoic acid foliar spray on amelioration of lead tolerance on Triticum aestivum L

Heavy metal pollution of water and soil has become a global issue, which extensively effect the major cereal crops and human health in the world. Current study aimed to conduct the role of exogenously applied Hydroxyl Benzoic Acid (HBA) foliar spray on agronomic and physicochemical parameters of two varieties of Triticum aestivum L. i.e. Jhanbaz and Galaxy 2013 under the lead (heavy metal) stress. Leaves of the above plants were treated (after 7, 14, 21 days) with distilled water (control), 2ppm Pb (T1), 2ppm Pb +HBA (T2),4 ppm Pb (T3), and 2ppm Pb +HBA (T4) and response of plants was observed at first, second and third week of the germination. Results of the lead (Pb) treatment of 4ppm and 2ppm showed high adverse effect on physiochemical and growth performance. Whereas HBA foliar spray revealed better performance by improving seedling vigorous index, agronomic parameters and percent field capacity under application of lead at 4ppm and 2ppm. This indicated that the toxic effects generated by heavy metal stress were relatively overcome by the application of HBA. However, results exhibited the better growth and physicochemical performance were recorded in Jhanbaz as compared to Galaxy 2013 and recommended variety under induced lead stress (lead).


Introduction
Heavy metal pollution of water and soil supplies has become a major problem in the modern world. Due to a direct interaction between these sources and the food chain, the excessive concentration of heavy metals is a serious threat to human life [1]. More heavy metal presentation to ground water through polluted soil plays a vital role in health and environmental aspects. Pb 2+ is one of the most toxic heavy metals without biological function, which is quickly absorbed by plants and it is toxic to living organisms even at low concentrations [2].
Inevitably, the use of industrial wastewater for agricultural land irrigation has skyrocketed due to water shortage crises and fertility benefits. Lead (Pb 2+ ) is a heavy metal of anthropogenic origin [3]. Pb 2+ is a pollutant that accumulates in soils, sediments and water and is extremely persistent in the environment [4]. Pb 2+ has no biological function and is toxic to living organisms, even at low concentrations. Although Pb 2+ is not an essential element, some plant species multiply in an area contaminated with Pb 2+ and accumulate it in different parts. The roots are the first organ in contact with various components of the rhizosphere [5]. Lead is absorbed by the plants through roots and caused disturbance of ions with in plants [6]. It has been speculated that lead toxic drugs may cause physiological and biochemical changes in the Oryza sativa L. [7]. Lead is not essential for a relatively high reactions of plant cells but it will remove this metal if it is present in their environment, especially in rural area where it is polluted by automobiles exhausts and in farms, contaminated with fertilizers containing heavy metals as impurities [8]. Plants take Pb 2+ from the solution in the soil at the roots, and then the largest amount of Pb 2+ accumulates in the roots in insoluble form [9]. Accumulation of lead in plants increases with an increase in plant lead levels. Lead can cause a wide range of physical and biochemical dysfunctions in seed germination, plant growth, water conditions and nitrate uptake [10][11][12]. Lead is one of the most widely used heavy metals and is highly toxic to plants [13]. Throughout the plant, Pb 2+ can affect photosynthesis at stoma levels, mesophyll cells, pigment content, and light and dark reactions. Heavy metal pollution of soil and water is a global environmental problem [14]. The objective of this study is to conduct the role of exogenously applied Hydroxyl Benzoic Acid (HBA) foliar spray on agronomic, and physicochemical parameters two varieties of Triticum aestivum L. such as Jhanbaz and Galaxy 2013 under the induced stress of heavy metal (lead).

Materials and Methods
Peshawar Industrial City Peshawar is a major producer of industrial wastewater in KPK Province. Due to their significant wastewater production, local farmers can use these alternative water resources for irrigation. Three samples of wastewater were taken from an industrial area of Peshawar city. The average concentration of Pb 2+ in industrial wastewater was determined by a nuclear absorption spectrophotometer (AAS) and ranged from 2 ppm to 4 ppm. To perform this measurement, a lab specialist pumped 100 ml of dirty water directly into the laboratory [15]. However, the presence of metallurgical fluids in wastewater prevents plants from growing due to its complex biocides and chemicals [16]. Treating mineral fluids was not reasonable or costeffective, so the wastewater was prepared with the infamous Pb 2+ solution (100 mg / 1) developed by Merck Millipour of Germany. Two different concentrations of solution were prepared, 4ppm and 2ppm, medium and strong wastewater was used in this study, respectively. The experiment was conducted during the 2015 wheat growing season at the Department of Botany, Bacha Khan University, Charsadda (latitude, 348 ‫˝080.34ط‬N, longitude, 7143ʹ50.880˝E) and altitude 282 m. Selected Local Blend Jhanbaz and Galaxy 2013 Triticum aestivum L. from Nowshera Cereal Crops Research Institute (CCRI). The seeds were sterilized in a solution of 10 ml of Clorox and 200 ml of water for 3 minutes and then washed with 50% ethanol for 3 minutes. After that, the seeds were rinsed with distilled water and planted in plastic pots (14 cm bottom inside diameter, 18.5 cm top inside diameter, 15.6 cm height and 0.5 cm depth). 'Thick) filled with air-dried soil and sand (3: 1) in triplicate pots. They were protected from the rain and 3 pots were submitted to each treatment. The total number of pots was 30. Plants were watered as needed. Sampling was performed 15 days after the start of treatment with heavy metals. For each treatment, 3 repetitions were taken. After the agronomic study, the samples were dried at room temperature for analysis of the heavy metal Pb 2+ . (20) Grams of soil of a uniform depth were taken 6 inches from the surfaces of the pots. Dry weight was determined after drying the soil in an oven for 72 hours at 70 °C until constant weight.

Soil moisture content
The %age moisture content of soil is calculated by following formula: %age moisture content = Soil Fresh weight − Soil Dry weight x100 ℎ ℎ

Field capacity of rhizospheric soil
The field capacity of rhizospheric soil was calculated following the method: Field Capacity (%) = Wet soil weight (g) − Dry soil weight (g) × 100 Dry soil weight (g)

Analysis of heavy metal lead for Rhizospheric soil and plant powder
Distilled water of 1 mL and 9 mL of rhizospheric clay extracts was taken into a test tube and lead was analyzed on an atomic absorption spectrophotometer. Micronutrients, micronutrients and heavy metals rhizome soil were measured by the formula: Nutrients (ppm) = (Extract in ppm -blank) × A_ × dilution factor W Whereas A = Total extract volume (ml) W = Rhizospheric soil dry weight Procedure Take the oven dried sample (0.25 g) in a 50 ml flask and add 6.5 ml of mixed acid solution, i.e. nitric acid, sulfuric acid, per chloric acid (5: 1: 0.1) and boil on a hot plate with extractor hood. Then a few drops of contaminated water were added and allowed to cool. The digested samples were then transferred to a 100 ml volumetric flask and the volume was increased to 100 ml by adding contaminated water. The extract was then filtered through whatsman # 42 filter paper and stored in plastic bottles labeled filtrate. The concentration of these elements throughout the sample was determined by the Shamadzo AA-670 nuclear absorption spectrophotometer.

Shoot and root length
Heavy metal stress directly affects the plant shoot and root length, the current study indicated that the maximum shoot length was documented in T2 (V1) and T1 (V2) whereas the lowest has been found in T1 (V1) and T5 (V2). After 14d treatment the maximum shoot length has been indicated in T5 (V1) with 28.6cm and T2 (V2), while the minimum has been found in T4 (V1) and T5 (V2). The maximum shoot length after 21d treatment was noted in T3 (V1) and T1 (V2), whereas the lowest has been reported in T4 (V1) and T2 (V2) ( Table 2). While after 7d treatment the maximum root length has been found in T1 (V1, V2) followed by T3 (V1, V2), while the lowest has been noted in T5 (V1, V2). After 14d treatment the maximum root length has been reported in T2 (V1) with 17.25cm and T4 (V2) with 11.05cm, whereas the lowest has been indicated in T5 (V1) and T3 (V2). The maximum root length has been found after 21d treatment in T3 (V1) and T4 (V2), while the lowest has been noted in T1 (V1) and T5 (V2). Soils contaminated with Pb 2+ cause sharp decreases in crop productivity there by poisoning a serious problem for agriculture (21) (Table 3). Similarly, result was also found that Retarded or no root and shoot formation was observed in the Triticum aestivum L. plant when expose to higher concentration of Cr

Conclusion
The effect of heavy metal (lead) research can be applied to so many current wheat problems including adverse effect on crop productivity. Keeping in views of these problems the present study was aimed to evaluate the effect of heavy metal (lead) on Triticum aestivum L. in response to hydro benzoic acid foliar spray. Results postulated that this lead had adverse effect on Triticum aestivum L. seedling agronomic characters. The effect of heavy metal (lead) resulted reduction in growth parameters in wheat has been improved by exogenous foliar application of hydro benzoic acid (HBA) thus illustrated that hydro benzoic acid plays a positive role in enhancing plant growth under heavy metal stress.