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Palmarosa [Cymbopogon martinii (Roxb.) Wats.] as a putative crop for phytoremediation, in tannery sludge polluted soil
Ecotoxicology and Environmental Safety 122 (2015) 296–302
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Palmarosa [Cymbopogon martinii (Roxb.) Wats.] as a putative crop for phytoremediation, in tannery sludge polluted soil Janhvi Pandey, Sukhmal Chand, Shipra Pandey, Rajkumari, D.D. Patra n Division of Agronomy & Soil Science, CSIR-Central Institute of Medicinal and Aromatic Plants (Council of Scientific and Industrial Research), PO-CIMAP, Lucknow 221615 Uttar Pradesh, India
art ic l e i nf o
a b s t r a c t
Article history: Received 5 May 2015 Received in revised form 30 July 2015 Accepted 6 August 2015
A field experiment using tannery sludge as a soil amendment material and palmarosa (Cymbopogon martinii) as a potential phytostabilizer was conducted to investigate their synergistic effect in relation to the improvement in soil quality/property. Three consecutive harvests of two cultivars of palmarosa-PRC1 and Trishna, were examined to find out the influence of different tannery sludge doses on their herb, dry matter, essential oil yield and heavy metal accumulation. Soil fertility parameters (N, P, K, Organic carbon) were markedly affected by different doses of sludge. Enhanced soil nitrogen was positively correlated with herb yield (0.719*) and plant height (0.797*). The highest dose of tannery sludge (100 t ha 1) exhibited best performance than other treatments with respect to herb, dry matter and oil yield in all three harvests. Trishna was found to be superior to PRC-1 in relation to same studied traits. Quality of oil varied, but was insignificant statistically. Uptake of heavy metals followed same order (Cr4Ni 4 Pb 4Cd) in roots and shoots. Translocation factor o1 for all trace elements and Bioconcentration factor 4 1 was observed in case of all heavy metals. Overall, tannery sludge enhanced the productivity of crop and metal accumulation occurred in roots with a meager translocation to shoots, hence it can be used as a phytostabiliser. The major advantage of taking palmarosa in metal polluted soil is that unlike food and agricultural crops, the product (essential oil) is extracted by hydro-distillation and there is no chance of oil contamination, thus is commercially acceptable. & 2015 Elsevier Inc. All rights reserved.
Keywords: Cymbopogon martinii Heavy metals Herb yield Phytostabiliser Tannery sludge
1. Introduction With the advent of industrialization and luxurious livelihood, ever increasing problem of pollution followed in our society. In this context, heavy metal pollution is posing a great threat to the existing livelihood as well as its environment. Tannery effluents contribute mainly in this regard. India ranks 6th in the world for leather production and at present, there are about 3000 tanneries processing about 600 million kg of raw skin and hide per annum generating around 50 million liters per day of liquid waste and 305 million kg of solid waste (Ahamed et al., 2014). Tanning is the process by which raw animal hides are converted into leather and mainly two methods are employed for the same-vegetable tanning (by plant derived tannins) and mineral tanning (by chromium in
Abbreviations: BF, Bioaccumulation factor; BCF, Bioconcentration factor; CETP, Common Effluent Treatment Plants; RBD, Randomized block design; TF, Translocation factor n Corresponding author. Fax: þ91 522 2342666/2719072. E-mail addresses: [email protected], [email protected] (D.D. Patra). http://dx.doi.org/10.1016/j.ecoenv.2015.08.005 0147-6513/& 2015 Elsevier Inc. All rights reserved.
the form of basic chromium sulfate). Chrome tanning is faster than vegetable tanning (less than a day for this part of the process) hence, it is frequently used. In India, tanneries give out about 2000–3000 tones of chromium into the environment annually, with concentrations ranging between 2000 and 5000 mg/l in the aqueous effluent (Ahamed et al., 2014). The pollution load has been estimated to be 50% more in weight than the weight of the hides processed from the tanning activity due to the usage of 175 different chemicals. Only about 20% of these chemicals used in this tanning process are absorbed by leather, the rest are released as wastes (UNIDO, 2005). Although, the Common Effluent Treatment Plants (CETP) treat the liquid wastes satisfactorily, still solid wastes from tanneries remain the main cause of concern. Large amounts of nutrient rich solid wastes or sludge are produced in treating waste water. Common mineral elements like Al, Fe, Ca, Na, K and Si are present in significant quantities in sludge. Trace elements like Cr, Cd, Pb, Hg, As, Cu, Ni, Zn, B, Se, Mo as well as N and P are also present in both organic and inorganic forms (Keswick.,1984). Tannery sludge could be an excellent material for soil amendment as it is found to improve the physical properties of soil and contain considerable amounts of plant nutrients (Frank, 1998; Naidu et al.,
J. Pandey et al. / Ecotoxicology and Environmental Safety 122 (2015) 296–302
1998; Tudunwada, 1998; Tidestrom, 1997; Carre et al., 1983). But with it, possible addition of heavy metals and toxic compounds in soil and through it in food chain, continue to be a matter of concern (,McBride, 2003; de las Heras et al., 2005). Plants should be screened according to their sensitivity at different sludge amendment ratios to achieve fertility benefits from sludge amendment, as heavy metal uptake, accumulation and tolerance levels differ in plants (Singh and Agarwal 2007). The process of metal uptake and accumulation by different plants depend on the concentration of available metals in soils, solubility sequences and the plant species growing on these soils (Chaney, 1973; Andersson 1977; Pahlsson, 1989; Kafka and Kuras 1997). Metal behavior in soil and plant uptake is strongly dependent on nature of metal, sludge/soil physico-chemical properties and plant species (McBride, 2003). Amendment of soil with sludge has been shown to increase the biomass of crops such as forage grasses, maize, sorghum and wheat (Fresquez et al., 1991; Akdeniz et al., 2006) and aromatic crops (Patel and Patra, 2014). Our present study was done keeping mainly two prospectives in mind. First, whether tannery sludge can be used as a soil amendment material in increasing the productivity of palmarosa (C. martinii) an aromatic crop and second, whether palmarosa can be identified as a potential phytostabilizer. Palmarosa, C. martinii (Roxb.) Wats. var. motia Burk., familyPoaceae, is an important multiharvest, perennial aromatic grass, which is cultivated mainly for its essential oil (commonly known as ‘rosha’ grass oil in India). It has a worldwide application in soap, perfumery and cosmetic industries. The oil has a sweet rose-like aroma with herbal note. The essential oil apart from its cosmetic use, is an effective anti-helminthic (Kumaran et al., 2003) and insect repellent for grains and legumes (Kumar et al., 2007). Of the total annual world production of palmarosa oil, India accounts for 70% (Lawrence, 1985) and is the principal producer and exporter of palmarosa oil and its products. The major risk in using tannery sludge as a soil amendment material, is its heavy metal content which can prove toxic for health; hence, we focused our research on an aromatic plant palmarosa, whose main product is its essential oil which is extracted through hydro-distillation and has no direct involvement in contamination of the economic produce (Khajanchi et al., 2013).
2. Materials and methods 2.1. Site description The present study was conducted in the Experimental farm of CSIR – Central Institute for Medicinal and Aromatic plants (CSIRCIMAP), Lucknow, India (Latitude 26.89°N; Longitude 80.94°E, 120 m above mean sea level), during the period 2013 to 2014. The climate experienced at the location is sub tropical humid and the soil was clay loam.
297
Table 1 Treatment details. S. No.
Treatments
T1 T2 T3 T4 T5 T6 T7 T8
No sludge and PRC-1 cultivar No sludge and Trishna cultivar 25 t ha 1 sludge and PRC-1 cultivar 50 t ha 1 sludge and PRC-1 cultivar 100 t ha 1 sludge and PRC-1 cultivar 25 t ha 1 sludge and Trishna cultivar 50 t ha 1 sludge and Trishna cultivar 100 t ha 1 sludge and Trishna cultivar
incubation period, 45 days old seedlings of the two varieties of palmarosa (PRC-1 and Trishna) which were healthy and uniformly growing in nursery were transplanted in those incubated beds at 45 30 cm spacing. Data of all the three harvests was recorded. 2.3. Soil sampling and analysis Soil samples were collected initially (prior to treatment application), after 50 days of incubation and after all the three harvests in triplicates of all the eight treatments from 15 cm. depth. The samples were air dried, crushed and passed through 2 mm sieve for chemical analysis. Electrical conductivity and pH were measured by conductivity meter and pH meter (Consort C861 model) respectively. Organic C was determined by Walkley and Black method (1934). Mineralisable nitrogen was determined by Subbiah and Asija (1956). Potassium was extracted with ammonium acetate and analyzed by flame photometry (Jackson, 1973). Available P was determined by the molybdo-phosphate blue color method (Olsen et al., 1954). For heavy metals (Cr, Cd, Ni, Pb) and micronutrients (Fe, Cu, Mn, Zn) estimation, soil was extracted with diethylene triamine pentacetic acid (DTPA) as prescribed by Lindsay and Norwell (1978) and then analysed by an inductively coupled plasma emission analyzer (ICP-OES), Perkin elmer model 53000V. 2.4. Estimation of vegetative parameters At regular intervals plant height, tiller numbers/plant, no. of clumps/bed was recorded. After each harvest, shoot samples were taken, likewise after third (final) harvest root samples were taken and their fresh weight, dry weight (after oven drying) were recorded in order to estimate the influence of different doses of tannery sludge on herb yield as well as uptake of different metals in root and shoot portion separately. 2.5. Estimation of chlorophyll content Chlorophyll a and Chlorophyll b content in plant leaves were estimated by Arnon method (Arnon, 1949).
2.2. Experimental design
2.6. Heavy metal analysis in plants
Eight treatment combinations (T1, T2, T3, T4, T5, T6, T7 and T8) consisting of four doses of tannery sludge (no sludge, 25 t ha 1, 50 t ha 1 and 100 t ha 1) and two cultivars of palmarosa (PRC-1 and Trishna) were tested (Table 1). Tannery sludge was brought from CSIR–CLRI resource center, Kanpur (India). It was dried, crushed and passed through 2 mm pore sized sieve. Processed sludge was applied to 2 2 m plot in April, 2013 and all treatments were replicated thrice in RBD (randomized block design). To avoid leaching, in each bed, polythene sheets were laid at about 1 m depth and then the treatments were applied. Beds were kept moist by regular irrigation and left for 50 days. After this
Root and shoot samples of plants were washed with 0.1 N HCl, deionised water and then with distilled water. They were then oven dried at 70 °C and acid digested (HNO3:HClO4 ¼10:4) for heavy metal and micronutrients analysis via ICP-OES, Perkin-Elmer model 53000V (Piper,1966, Page et al., 1992; Jones and Case, 1990). 2.7. Essential oil extraction Extraction of the essential oil from fresh leaves and inflorescence was carried out by hydro-distillation in a Clevenger-
100.4 7 27.28 124.0 7 6.67 126.7 7 6.37 130.3 7 3.39 137.7 7 5.82 123.7 7 5.05 134.5 7 2.85 139.8 7 2.85 0.1677 0.03 0.1557 0.02 0.1817 0.01 0.3187 0.06 0.5447 0.04 0.229 7 0.01 0.3157 0.01 0.5787 0.07 7.3 7 0.22 7.4 7 0.06 7.6 7 0.06 7.3 7 0.15 7.2 7 0.06 7.3 7 0.09 7.3 7 0.03 7.17 0.09 T1 T2 T3 T4 T5 T6 T7 T8
All the values are mean of triplicates 7Standard deviation.
Cu
5.79 7 0.93 6.06 7 1.03 6.50 7 0.82 9.70 7 0.62 17.03 7 1.73 7.11 7 0.99 10.117 1.99 11.88 7 1.47 1253 778.48 1240 710.01 1273 721.88 1280 717.34 1373 732.87 1310 720.84 1360 7229.40 1300 725.19 5.727 0.56 4.077 1.27 4.177 1.19 7.23 7 0.32 9.85 7 0.76 5.81 7 0.33 7.75 7 1.47 8.23 7 0.70 1.54 7 0.11 1.477 0.03 1.747 0.08 1.96 7 0.08 3.49 7 0.35 1.87 7 0.15 2.60 7 0.48 3.63 7 0.22 3.52 70.42 4.26 71.29 265 751.07 640 783.24 1480 7512.39 353.7 7143.08 639.0 750.59 1383.0 7304.79 *
N (kg/ha) OC (%) EC (ds/m) pH (1:2.5) Treatments
Table 2 Influence of tannery sludge application in soil after 50 days incubation.
Chlorophyll a and chlorophyll b were estimated and they were significantly affected by variation of treatments. It was observed that as the doses of tannery sludge increased, both parameters decreased gradually, this may be attributed to adverse effect on photosynthetic rate by accumulation of heavy metal and
P (kg/ha)
3.1.1. Initial status The initial soil samples (prior to treatment application) were analyzed and it showed following characteristics – pH 7.6, EC – 0.14 dS m 1, Organic carbon – 0.24%, Mineralisable Nitrogen – 245.95 kg ha 1, Available Phosphorous –18.68 kg ha 1, Potassium – 111.2k g ha 1.
3.2. Effect on chlorophyll content
Fe Pb
3.1. Effects on soil chemical composition
Ni
3. Results and discussions
3.1.2. Status after 50 days of incubation Addition of tannery sludge in field, exhibited a significant increase in pH, EC., OC, N, P, heavy metal (Cr, Ni, Pb) and micronutrients (Fe, Cu, Zn, Mn) after 50 days of incubation period. Electrical conductivity, organic carbon, nitrogen, phosphorus proportionately increased with supply of tannery sludge over control but pH decreased as rate of tannery sludge increased and minimum was recorded in T5 and T8 treatments where tannery sludge was applied 100 t ha 1 (Table 2). Similar observations were made by Patel and Patra (2014) in Pelargonium graveolens. Barajas (2001) observed that incubation increased N, C and P mineralization in soils amended with tannery sludge. Heavy metals and micronutrient content increased in direct proportion to the quantity of tannery sludge added to the field. The concentration of heavy metals in soil was in the following order: Cr4Pb 4Ni 4Cd (Table 2). At first harvest, enhanced soil organic carbon was positively correlated with nitrogen (0.772*), height of plants (0.836*), herb yield (0.83*) and dry weight of shoots (0.753*) whereas nitrogen was positively correlated with height of plants (0.797*) and herb yield (0.719*), (Table 3).
Cr
The experiment was performed in a randomized block design (RBD). Analysis of variance (ANOVA) was used for analyzing the data and least significant differences (LSD) were calculated using the F method (Sokal and Rholf, 1981). Differences at p o0.05 were considered significant. Uptake of heavy metals and micronutrients by plant samples was calculated by multiplying metal concentration in sample with its dry weight. Linear correlation coefficients between soil nitrogen and plant height and herb yield were also analyzed.
Micronutrients conc. (ppm)
2.9. Statistical analysis
Heavy metals conc. (ppm)
Mn
GC analysis of the essential oils was carried out on a PerkinElmer Auto System XL gas Chromatograph, equipped with DB-5 capillary column (50 m 0.32 mm i.d., film thickness 0.25 mm) and flame ionization detector (FID). Identification of the essential oil constituents was done on the basis of retention time (RT) and retention index (RI). The relative amounts of individual components were calculated based on the GC peak area (FID response).
99.5 7 1.45 87.5 7 3.33 144.5 7 2.73 183.157 2.25 222 7 8.07 117.75 7 2.7 174.577 9.94 190.707 0.57
Zn
2.8. Gas chromatography analysis of essential oil
353.0 7 26.68 384.0 7 8.88 400.0 7 17.76 569.0 7 62.25 676.0 7 64.12 353.0 7 8.89 454.6 7 34.78 594.6 7 57.27
type apparatus for 2 h. Distilled essential oil was dried over anhydrous Na2SO4 and stored at 4 °C prior to analysis.
11.39 7 1.62 12.93 7 1.11 12.50 7 1.10 17.75 7 0.38 28.87 7 2.81 13.977 1.09 17.48 7 3.15 21.87 7 1.39
J. Pandey et al. / Ecotoxicology and Environmental Safety 122 (2015) 296–302
0.49 70.03 0.57 70.03 0.71 70.04 0.70 70.02 0.81 70.05 0.68 70.07 0.73 70.03 0.84 70.05
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Table 3 Correlation coefficients between different parameters at first harvest.
OC (%) Nitrogen Height Herb yield *
Nitrogen
Height
Herb yield
Dry wt. of shoot
0.772*
0.836* 0.797*
0.83* 0.719* 0.798*
0.753* 0.585 0.71* 0.924*
Correlation is significant at 0.05 level.
production of Reactive Oxygen Species (Ghnaya et al., 2009). Hence, chlorophyll content has negative correlation with the sludge treatments. 3.3. Effect on herb yield Herb yield of palmarosa (C. martini) in all the three harvests was significantly affected by the treatment variation. Highest herb yield was recorded with 100 t ha 1 of tannery sludge application in both the cultivars of palmarosa (PRC-1 and Trishna). Similar observations were made by Singh and Agarwal (2010) on herb yield of rice at different sludge amendment rates. Among cultivars, Trishna produced higher biomass at each level (25, 50, 100 t ha 1) of sludge application than PRC-1. Biomass yield of palmarosa was recorded higher in first and third harvest as compared to IInd harvest. Lower biomass yield in IInd harvest is attributed to low temperature and relatively less availability of nutrition during October to February for crop as low temperature affects the growth of grasses adversely (Ivory and Whiteman, 1978). Trishna produced about 9.9, 16.0, 49.0% higher herb yield over its respective control, with application of 25, 50 and 100 t ha 1 sludge application, respectively in first harvest. Similar trend was observed with PRC-1 (Fig. 2). 3.4. Effect on shoot and root dry matter yield Like herb yield, variation in treatment significantly affected dry matter yield. Highest dry matter yield was recorded in T5 and T8 treatments in all the three harvests where tannery sludge was applied at the rate of 100 t ha 1. Dry matter yield was increased by 26 and 28% in T5 and T8, respectively over their respective controls in first harvest. Amendment of soil with sludge has been shown to increase the biomass and dry matter yield of crops such as forage grasses, maize, sorghum and wheat (Fresquez et al., 1991; Akdeniz et al., 2006) and aromatic crops (Patel and Patra, 2014). Among three harvests, low dry matter yield was observed in second harvest when crop was grown during November to February due to low temperature. Ivory and Whiteman (1978)
299
observed that low temperature adversely affected the growth of grasses; hence dry matter yield was also negatively affected. It was again increased, when temperature raised from February last to June as indicated in third harvest. Trishna performed better at all three doses of tannery sludge applied at 25, 50 and 100 t ha 1, than PRC-1. Dry weight of roots was significantly affected with treatment variation. Root weight of PRC-1 reduced by about 48, 33 and 2% at 25, 50 and 100 t ha 1 application of tannery sludge, respectively over its control. Similar trend was followed by Trishna. At higher dose of tannery sludge (100 t ha 1) application, reduction in root weight was very low as compared to low rate of tannery sludge application in both the cultivars (PRC-1, Trishna) of palmarosa. It may be attributed to higher supply of organic carbon which is the key input to mitigate the toxic effect of heavy metals on root growth. 3.5. Effect on oil yield and quality Significant effect of variation in treatment was again observed in context to oil yield. Highest oil yield was observed in T5 and T8 treatments in which 100 t ha 1 sludge was applied (Fig. 2). There are two important constituents of essential oil of palmarosa which are known as Geraniol and Geranyl acetate. Oil quality depends upon its constituents which are further dependent on various factors such as environmental conditions, biotic stress, etc. (Patra et al., 2000). Variations in geraniol content were observed in all the three harvests but were not statistically significant. Average across all the three harvests indicated that geraniol content in PRC-1 marginally reduced at all three levels (25, 50, 100) of tannery sludge application compared to its control but it slightly increased in Trishna, over control. Geranyl acetate significantly differed in first harvest but not in second and third harvests. Average of three harvests indicated that geranyl acetate increased in PRC-1 and Trishna by 7, 11 and 25 and 6, 14 and 32% over its control, respectively at 25, 50 and 100 t ha 1 of tannery sludge application. 3.6. Status of post harvest soil Electrical conductivity, pH, organic carbon, nitrogen, phosphorus and potassium were significantly affected by treatments (Fig. 1). All these parameters including pH were reduced as compared to status of soil after 50 days incubation. Reduction in electrical conductivity may be due to leaching of soluble salts and its utilization by plants for its growth. Similarly, mineralization of organic carbon as a result of high temperature and humidity may be responsible for reduction of carbon content in post harvest soil. Nitrogen, phosphorus and potassium reduced by 25–56% over its
Fig. 1. Soil status at three different time intervals (initial, after 50 days incubation and after harvest).
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Fig. 2. Herb yield (t ha 1) and oil yield (l ha 1) in three consecutive harvests in all eight treatments of palmarosa.
application than PRC-1, respectively. Nickel uptake varied from 1.17 to 3.62, 0.2 to 0.39 and 0.035 to 0.122 kg ha 1, in first, second and third harvest, respectively. Uptake of nickel gradually decreased from first to third harvest which is due to reducing concentration of this element in soil. Total of all the three harvests indicated that Ni uptake in PRC-1 was 33, 106 and 160% higher with application of 25, 50 and 100 t ha 1 sludge, respectively over control. The corresponding increase in Trishna was 30, 118, and 137% respectively, over control (Table 4a). Results indicated that maximum Pb uptake in shoot portion occurred in first harvest, followed by third and minimum uptake was observed in second harvest. This may be attributed to less herb yield during second harvest as compared to other two harvests due to unfavorable weather conditions. Uptake varied from 1.4 to 5.22, 0.05 to 0.26, 0.02 to 0.15 kg ha 1 in first, second and third harvest respectively, Table 4(a).
initial status, in post harvest soil. Treatment variation significantly affected the chromium, nickel and lead content in postharvest soil and these ranged between 2.95–60.5, 1.38–2.60 and 3.62– 9.85 ppm respectively. Magnitude of chromium content was higher followed by lead and nickel. However, concentration of all three metals was lower than the concentration after 50 days incubation. Like metals, iron, copper, manganese and zinc content in post harvest soil was also recorded lower as compared to initial content in soil. A comparison between status of initial, at 50 days incubation and post harvest soil has been shown in Fig. 1. 3.7. Assessment of phytoremedial potential of two cultivars of palmarosa Accumulation of trace metals by plants determines both micronutrient content and heavy metal concentration. Various complex transport and chelating activities control rates of metal uptake in plants.
3.7.2. Micronutrients uptake Maximum iron uptake was recorded in first harvest followed by third and second in all treatments. Iron uptake increased by 11, 12 and 13 times in PRC-1 and 10, 11, and 12 times in Trishna with application of 25, 50 and 100 t ha 1 of tannery sludge, respectively over their control, in first harvest. Lowest uptake of iron was observed in second harvest. It may be attributed to minimum herb yield among all three harvests. Manganese uptake was recorded highest in first harvest but it was almost same in second and third. Total of three harvests indicated that Trishna has higher uptake of manganese as compared to PRC-1 at 25, 50 and 100 t ha 1 of tannery sludge application. Zinc uptake varied from 20.03 to 28.73, 0.44 to 0.93 and 0.32 to 1.23 kg ha 1 in first, second and third harvest respectively. Cumulative uptake of three harvests exhibited that Mn uptake increased in PRC-1, 13, 14, and 25% and in Trishna 11, 20 and 38% at 25, 50 and 100 t ha 1 of tannery sludge application, respectively. Maximum copper uptake was recorded
3.7.1. Heavy metal uptake in shoot portion Uptake of heavy metals was calculated by multiplying metal concentration with dry matter and the order of uptake was observed as Cr4Pb 4Ni 4Cd (Table 4a). Similar observations were made by Gupta and Sinha (2006) in Sesamum indicum and Gupta and Sinha (2007) in Brassica juncea. Total chromium uptake of three harvests of palmarosa crop, indicated that it ranges from 4.88 to 18.33 kg ha 1 during one year of crop growth. Maximum Cr uptake was recorded in first harvest followed by second and third. Although dry matter was lowest in second harvest but higher uptake may be attributed to high concentration of chromium during second harvest. Trishna has higher uptake of chromium than PRC-1. Chromium uptake in Trishna was observed to be 40, 32, and 11% higher at 25, 50 and 100 t ha 1 of tannery sludge Table 4 (a): Heavy metal uptake (kg ha 1) in shoot portion in three consecutive harvests. Treatments
T1 T2 T3 T4 T5 T6 T7 T8 CD (5%)
Cr
Ni
Pb
Cd
I
II
III
I
II
III
I
II
III
I
II
III
1.75 2.48 4.52 5.90 8.90 6.90 7.25 8.85 1.34
1.56 1.90 2.83 3.19 4.88 3.52 4.64 5.56 0.83
1.57 1.64 1.39 2.62 2.71 1.84 3.57 3.92 0.588
1.17 1.47 1.62 2.63 3.30 1.94 3.28 3.62 0.59
0.20 0.24 0.21 0.23 0.31 0.27 0.36 0.39 0.062
0.035 0.038 0.041 0.047 0.056 0.049 0.079 0.122 0.047
2.039 3.224 1.485 2.398 5.214 2.033 3.811 3.128 1.232
0.051 0.022 0.125 0.262 0.056 0.056 0.132 0.059 0.048
0.063 0.054 0.139 0.081 0.083 0.156 0.109 0.029 0.058
0.478 0.439 0.446 0.789 0.929 0.575 0.562 0.599 0.177
0.003 0.004 0.004 0.007 0.008 0.005 0.006 0.008 0.042
0.086 0.102 0.091 0.076 0.079 0.071 0.098 0.085 0.022
*All the values are mean of triplicates.
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Table 4 (b): Heavy metal and micronutrient uptake (kg ha 1) in root portion. Treatments
Heavy metals
T1 T2 T3 T4 T5 T6 T7 T8 CD (5%)
Micronutrients
Cr
Ni
Pb
Cd
Fe
Mg
Mn
Cu
Zn
0.446 0.698 1.269 0.422 0.784 1.272 1.187 1.267 1.003
0.103 0.091 0.088 0.046 0.066 0.116 0.088 0.052 0.059
0.023 0.013 0.017 0.019 0.012 0.012 0.011 0.010 0.013
0.001 0.003 0.005 0.007 0.005 0.005 0.005 0.007 0.005
17.39 11.578 10.40 9.138 9.201 10.808 9.305 6.246 6.378
9.758 7.55 6.806 4.885 5.281 6.935 6.869 4.080 4.039
0.332 0.237 0.233 0.178 0.194 0.241 0.195 0.128 0.140
0.235 0.345 0.338 0.156 0.199 0.112 0.082 0.198 0.161
0.186 0.076 0.177 0.147 0.128 0.138 0.208 0.141 0.116
*All the values are mean of triplicates.
Table 5 (a): Bioconcentration Factor (BCF) and Translocation Factor (TF) of heavy metals and micronutrients of two cultivars of palmarosa at different rates of tannery sludge application. Treatments
T1 T2 T3 T4 T5 T6 T7 T8
BCF
TF
Cr
Ni
Pb
Cd
Fe
Cu
Mn
Zn
Cr
Pb
Ni
Cd
Fe
Cu
Mn
Zn
28.42 38.24 2.03 1.28 1.13 1.08 1.67 1.52
132.86 62.95 52.03 44.62 11.45 72.42 46.32 1.65
1.22 1.49 2.35 2.02 1.02 1.43 1.12 1.09
0.15 1.77 2.34 14.82 1.72 1.25 1.60 2.90
4.81 4.01 3.99 4.57 3.04 2.78 2.61 1.89
37.06 107.93 48.67 23.80 7.79 15.53 7.04 12.84
0.92 0.75 0.88 0.89 0.76 0.66 0.58 0.56
5.10 5.13 5.28 4.07 1.53 2.81 3.43 2.63
0.07 0.05 0.01 0.01 0.03 0.08 0.04 0.02
0.37 0.25 0.47 0.24 0.55 0.92 0.71 0.19
0.06 0.03 0.05 0.06 0.06 0.08 0.03 0.13
0.05 0.004 0.04 0.002 0.004 0.008 0.008 0.003
0.19 0.09 0.49 0.09 0.29 0.11 0.12 0.22
0.05 0.02 0.03 0.04 0.04 0.12 0.15 0.05
0.25 0.26 0.31 0.24 0.27 0.31 0.28 0.23
0.33 0.52 0.34 0.36 0.55 0.75 0.49 0.48
Table 5 (b): Bioaccumulation factor (BF) of heavy metals in two cultivars of palmarosa at different rates of tannery sludge application. Treatments
T1 T2 T3 T4 T5 T6 T7
I
II
III
Cr
Ni
Pb
Cd
Cr
Ni
Pb
Cd
Cr
Ni
Pb
Cd
4.29 6.2 0.043 0.035 0.01 0.12 0.03
2.67 1.75 1.39 1.09 0.77 1.80 0.61
1.18 1.49 1.27 0.93 0.67 1.92 1.02
11.94 8.22 0.92 0.84 0.32 0.92 0.48
0.57 0.69 0.039 0.019 0.01 0.07 0.03
7.66 5.29 5.77 5.12 2.68 5.01 5.65
0.61 0.82 1.36 1.97 0.39 0.47 0.92
2.16 1 0.36 0.22 0.19 0.65 0.26
1.89 1.98 0.02 0.01 0.003 0.08 0.03
8.57 1.62 2.86 2.77 0.64 5.60 1.50
0.45 0.38 1.10 0.49 0.31 1.31 0.48
0.007 0.007 0.011 0.041 0.003 0.010 0.013
in first harvest followed by second and third in all treatments. Trishna has higher uptake of copper as compared to PRC-1 in all treatments. 3.7.3. Heavy metal uptake in roots The order of heavy metal uptake was Cr4 Ni4Pb 4 Cd in root of palmarosa and micronutrient uptake showed following order: Fe4 Mg 4Cu 4Mn 4Zn, Table 4(b). Translocation factor (TF), Bioconcentration factor (BCF) and Bioaccumulation factor (BF) are important in identifying plants suitable for phytostabilization. Plants with TF o1 and BCF 4 1 are taken as potential phytostabilisers as most of the metals get accumulated in their root portion with a very little translocation to the aerial parts (Mendez and Maier, 2008). 3.8. Translocation factor (TF) Ability of plants to translocate heavy metals from root to shoot is measured by calculating TF. Here, TF o1 was observed for each heavy metal. Hence it shows that only a meager translocation of
metals took place from root to shoot. High accumulation of heavy metals in roots may be ascribed to complexation of heavy metals with sulphydryl groups resulting in less translocation of heavy metals to shoots (Singh et al., 2004), Table 5(a). 3.9. Bioconcentration factor (BCF) It is the ratio of concentration of metals in roots to that in soil. BCF4 1 was observed for all heavy metals. Greater accumulation of heavy metals occurred in root portion of palmarosa. Thus, our test indicates that the crop can tolerate heavy metal toxicity and can grow well in multi-metal contaminated soil, Table 5(a). 3.10. Bioaccumulation factor (BF) It is the ratio of metal concentration in shoots to concentration in soil. By calculating BF of all trace elements for all the three harvests, it came out to be less than their control. It indicated that, heavy metals were not accumulated from soil in the aerial parts of plant. Moreover, BF is highest at low concentration of sludge
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application and decreased with increasing concentration, (Suter et al., 2000, Greger, 2004), Table 5(b).
4. Conclusions Our present study indicated that tannery sludge improved the fertility of soil; hence herb, dry matter and essential oil yield of palmarosa increased significantly. Moreover, cultivar Trishna proved to be better than PRC-1 in all aspects. TF o1 and BCF 41 were observed for all heavy metals, hence it can be concluded that palmarosa can be adopted as a putative candidate for phytostabilisation, in heavy metal rich tannery sludge treated soil.
Acknowledgements The authors are thankful to the Director, CIMAP, Lucknow, India, for providing the necessary facilities during the course of this investigation. Thanks are also due to CSIR, New Delhi for financial assistance through Network Project ‘INDEPTH’.
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Ecotoxicology and Environmental Safety journal homepage: www.elsevier.com/locate/ecoenv
Palmarosa [Cymbopogon martinii (Roxb.) Wats.] as a putative crop for phytoremediation, in tannery sludge polluted soil Janhvi Pandey, Sukhmal Chand, Shipra Pandey, Rajkumari, D.D. Patra n Division of Agronomy & Soil Science, CSIR-Central Institute of Medicinal and Aromatic Plants (Council of Scientific and Industrial Research), PO-CIMAP, Lucknow 221615 Uttar Pradesh, India
art ic l e i nf o
a b s t r a c t
Article history: Received 5 May 2015 Received in revised form 30 July 2015 Accepted 6 August 2015
A field experiment using tannery sludge as a soil amendment material and palmarosa (Cymbopogon martinii) as a potential phytostabilizer was conducted to investigate their synergistic effect in relation to the improvement in soil quality/property. Three consecutive harvests of two cultivars of palmarosa-PRC1 and Trishna, were examined to find out the influence of different tannery sludge doses on their herb, dry matter, essential oil yield and heavy metal accumulation. Soil fertility parameters (N, P, K, Organic carbon) were markedly affected by different doses of sludge. Enhanced soil nitrogen was positively correlated with herb yield (0.719*) and plant height (0.797*). The highest dose of tannery sludge (100 t ha 1) exhibited best performance than other treatments with respect to herb, dry matter and oil yield in all three harvests. Trishna was found to be superior to PRC-1 in relation to same studied traits. Quality of oil varied, but was insignificant statistically. Uptake of heavy metals followed same order (Cr4Ni 4 Pb 4Cd) in roots and shoots. Translocation factor o1 for all trace elements and Bioconcentration factor 4 1 was observed in case of all heavy metals. Overall, tannery sludge enhanced the productivity of crop and metal accumulation occurred in roots with a meager translocation to shoots, hence it can be used as a phytostabiliser. The major advantage of taking palmarosa in metal polluted soil is that unlike food and agricultural crops, the product (essential oil) is extracted by hydro-distillation and there is no chance of oil contamination, thus is commercially acceptable. & 2015 Elsevier Inc. All rights reserved.
Keywords: Cymbopogon martinii Heavy metals Herb yield Phytostabiliser Tannery sludge
1. Introduction With the advent of industrialization and luxurious livelihood, ever increasing problem of pollution followed in our society. In this context, heavy metal pollution is posing a great threat to the existing livelihood as well as its environment. Tannery effluents contribute mainly in this regard. India ranks 6th in the world for leather production and at present, there are about 3000 tanneries processing about 600 million kg of raw skin and hide per annum generating around 50 million liters per day of liquid waste and 305 million kg of solid waste (Ahamed et al., 2014). Tanning is the process by which raw animal hides are converted into leather and mainly two methods are employed for the same-vegetable tanning (by plant derived tannins) and mineral tanning (by chromium in
Abbreviations: BF, Bioaccumulation factor; BCF, Bioconcentration factor; CETP, Common Effluent Treatment Plants; RBD, Randomized block design; TF, Translocation factor n Corresponding author. Fax: þ91 522 2342666/2719072. E-mail addresses: [email protected], [email protected] (D.D. Patra). http://dx.doi.org/10.1016/j.ecoenv.2015.08.005 0147-6513/& 2015 Elsevier Inc. All rights reserved.
the form of basic chromium sulfate). Chrome tanning is faster than vegetable tanning (less than a day for this part of the process) hence, it is frequently used. In India, tanneries give out about 2000–3000 tones of chromium into the environment annually, with concentrations ranging between 2000 and 5000 mg/l in the aqueous effluent (Ahamed et al., 2014). The pollution load has been estimated to be 50% more in weight than the weight of the hides processed from the tanning activity due to the usage of 175 different chemicals. Only about 20% of these chemicals used in this tanning process are absorbed by leather, the rest are released as wastes (UNIDO, 2005). Although, the Common Effluent Treatment Plants (CETP) treat the liquid wastes satisfactorily, still solid wastes from tanneries remain the main cause of concern. Large amounts of nutrient rich solid wastes or sludge are produced in treating waste water. Common mineral elements like Al, Fe, Ca, Na, K and Si are present in significant quantities in sludge. Trace elements like Cr, Cd, Pb, Hg, As, Cu, Ni, Zn, B, Se, Mo as well as N and P are also present in both organic and inorganic forms (Keswick.,1984). Tannery sludge could be an excellent material for soil amendment as it is found to improve the physical properties of soil and contain considerable amounts of plant nutrients (Frank, 1998; Naidu et al.,
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1998; Tudunwada, 1998; Tidestrom, 1997; Carre et al., 1983). But with it, possible addition of heavy metals and toxic compounds in soil and through it in food chain, continue to be a matter of concern (,McBride, 2003; de las Heras et al., 2005). Plants should be screened according to their sensitivity at different sludge amendment ratios to achieve fertility benefits from sludge amendment, as heavy metal uptake, accumulation and tolerance levels differ in plants (Singh and Agarwal 2007). The process of metal uptake and accumulation by different plants depend on the concentration of available metals in soils, solubility sequences and the plant species growing on these soils (Chaney, 1973; Andersson 1977; Pahlsson, 1989; Kafka and Kuras 1997). Metal behavior in soil and plant uptake is strongly dependent on nature of metal, sludge/soil physico-chemical properties and plant species (McBride, 2003). Amendment of soil with sludge has been shown to increase the biomass of crops such as forage grasses, maize, sorghum and wheat (Fresquez et al., 1991; Akdeniz et al., 2006) and aromatic crops (Patel and Patra, 2014). Our present study was done keeping mainly two prospectives in mind. First, whether tannery sludge can be used as a soil amendment material in increasing the productivity of palmarosa (C. martinii) an aromatic crop and second, whether palmarosa can be identified as a potential phytostabilizer. Palmarosa, C. martinii (Roxb.) Wats. var. motia Burk., familyPoaceae, is an important multiharvest, perennial aromatic grass, which is cultivated mainly for its essential oil (commonly known as ‘rosha’ grass oil in India). It has a worldwide application in soap, perfumery and cosmetic industries. The oil has a sweet rose-like aroma with herbal note. The essential oil apart from its cosmetic use, is an effective anti-helminthic (Kumaran et al., 2003) and insect repellent for grains and legumes (Kumar et al., 2007). Of the total annual world production of palmarosa oil, India accounts for 70% (Lawrence, 1985) and is the principal producer and exporter of palmarosa oil and its products. The major risk in using tannery sludge as a soil amendment material, is its heavy metal content which can prove toxic for health; hence, we focused our research on an aromatic plant palmarosa, whose main product is its essential oil which is extracted through hydro-distillation and has no direct involvement in contamination of the economic produce (Khajanchi et al., 2013).
2. Materials and methods 2.1. Site description The present study was conducted in the Experimental farm of CSIR – Central Institute for Medicinal and Aromatic plants (CSIRCIMAP), Lucknow, India (Latitude 26.89°N; Longitude 80.94°E, 120 m above mean sea level), during the period 2013 to 2014. The climate experienced at the location is sub tropical humid and the soil was clay loam.
297
Table 1 Treatment details. S. No.
Treatments
T1 T2 T3 T4 T5 T6 T7 T8
No sludge and PRC-1 cultivar No sludge and Trishna cultivar 25 t ha 1 sludge and PRC-1 cultivar 50 t ha 1 sludge and PRC-1 cultivar 100 t ha 1 sludge and PRC-1 cultivar 25 t ha 1 sludge and Trishna cultivar 50 t ha 1 sludge and Trishna cultivar 100 t ha 1 sludge and Trishna cultivar
incubation period, 45 days old seedlings of the two varieties of palmarosa (PRC-1 and Trishna) which were healthy and uniformly growing in nursery were transplanted in those incubated beds at 45 30 cm spacing. Data of all the three harvests was recorded. 2.3. Soil sampling and analysis Soil samples were collected initially (prior to treatment application), after 50 days of incubation and after all the three harvests in triplicates of all the eight treatments from 15 cm. depth. The samples were air dried, crushed and passed through 2 mm sieve for chemical analysis. Electrical conductivity and pH were measured by conductivity meter and pH meter (Consort C861 model) respectively. Organic C was determined by Walkley and Black method (1934). Mineralisable nitrogen was determined by Subbiah and Asija (1956). Potassium was extracted with ammonium acetate and analyzed by flame photometry (Jackson, 1973). Available P was determined by the molybdo-phosphate blue color method (Olsen et al., 1954). For heavy metals (Cr, Cd, Ni, Pb) and micronutrients (Fe, Cu, Mn, Zn) estimation, soil was extracted with diethylene triamine pentacetic acid (DTPA) as prescribed by Lindsay and Norwell (1978) and then analysed by an inductively coupled plasma emission analyzer (ICP-OES), Perkin elmer model 53000V. 2.4. Estimation of vegetative parameters At regular intervals plant height, tiller numbers/plant, no. of clumps/bed was recorded. After each harvest, shoot samples were taken, likewise after third (final) harvest root samples were taken and their fresh weight, dry weight (after oven drying) were recorded in order to estimate the influence of different doses of tannery sludge on herb yield as well as uptake of different metals in root and shoot portion separately. 2.5. Estimation of chlorophyll content Chlorophyll a and Chlorophyll b content in plant leaves were estimated by Arnon method (Arnon, 1949).
2.2. Experimental design
2.6. Heavy metal analysis in plants
Eight treatment combinations (T1, T2, T3, T4, T5, T6, T7 and T8) consisting of four doses of tannery sludge (no sludge, 25 t ha 1, 50 t ha 1 and 100 t ha 1) and two cultivars of palmarosa (PRC-1 and Trishna) were tested (Table 1). Tannery sludge was brought from CSIR–CLRI resource center, Kanpur (India). It was dried, crushed and passed through 2 mm pore sized sieve. Processed sludge was applied to 2 2 m plot in April, 2013 and all treatments were replicated thrice in RBD (randomized block design). To avoid leaching, in each bed, polythene sheets were laid at about 1 m depth and then the treatments were applied. Beds were kept moist by regular irrigation and left for 50 days. After this
Root and shoot samples of plants were washed with 0.1 N HCl, deionised water and then with distilled water. They were then oven dried at 70 °C and acid digested (HNO3:HClO4 ¼10:4) for heavy metal and micronutrients analysis via ICP-OES, Perkin-Elmer model 53000V (Piper,1966, Page et al., 1992; Jones and Case, 1990). 2.7. Essential oil extraction Extraction of the essential oil from fresh leaves and inflorescence was carried out by hydro-distillation in a Clevenger-
100.4 7 27.28 124.0 7 6.67 126.7 7 6.37 130.3 7 3.39 137.7 7 5.82 123.7 7 5.05 134.5 7 2.85 139.8 7 2.85 0.1677 0.03 0.1557 0.02 0.1817 0.01 0.3187 0.06 0.5447 0.04 0.229 7 0.01 0.3157 0.01 0.5787 0.07 7.3 7 0.22 7.4 7 0.06 7.6 7 0.06 7.3 7 0.15 7.2 7 0.06 7.3 7 0.09 7.3 7 0.03 7.17 0.09 T1 T2 T3 T4 T5 T6 T7 T8
All the values are mean of triplicates 7Standard deviation.
Cu
5.79 7 0.93 6.06 7 1.03 6.50 7 0.82 9.70 7 0.62 17.03 7 1.73 7.11 7 0.99 10.117 1.99 11.88 7 1.47 1253 778.48 1240 710.01 1273 721.88 1280 717.34 1373 732.87 1310 720.84 1360 7229.40 1300 725.19 5.727 0.56 4.077 1.27 4.177 1.19 7.23 7 0.32 9.85 7 0.76 5.81 7 0.33 7.75 7 1.47 8.23 7 0.70 1.54 7 0.11 1.477 0.03 1.747 0.08 1.96 7 0.08 3.49 7 0.35 1.87 7 0.15 2.60 7 0.48 3.63 7 0.22 3.52 70.42 4.26 71.29 265 751.07 640 783.24 1480 7512.39 353.7 7143.08 639.0 750.59 1383.0 7304.79 *
N (kg/ha) OC (%) EC (ds/m) pH (1:2.5) Treatments
Table 2 Influence of tannery sludge application in soil after 50 days incubation.
Chlorophyll a and chlorophyll b were estimated and they were significantly affected by variation of treatments. It was observed that as the doses of tannery sludge increased, both parameters decreased gradually, this may be attributed to adverse effect on photosynthetic rate by accumulation of heavy metal and
P (kg/ha)
3.1.1. Initial status The initial soil samples (prior to treatment application) were analyzed and it showed following characteristics – pH 7.6, EC – 0.14 dS m 1, Organic carbon – 0.24%, Mineralisable Nitrogen – 245.95 kg ha 1, Available Phosphorous –18.68 kg ha 1, Potassium – 111.2k g ha 1.
3.2. Effect on chlorophyll content
Fe Pb
3.1. Effects on soil chemical composition
Ni
3. Results and discussions
3.1.2. Status after 50 days of incubation Addition of tannery sludge in field, exhibited a significant increase in pH, EC., OC, N, P, heavy metal (Cr, Ni, Pb) and micronutrients (Fe, Cu, Zn, Mn) after 50 days of incubation period. Electrical conductivity, organic carbon, nitrogen, phosphorus proportionately increased with supply of tannery sludge over control but pH decreased as rate of tannery sludge increased and minimum was recorded in T5 and T8 treatments where tannery sludge was applied 100 t ha 1 (Table 2). Similar observations were made by Patel and Patra (2014) in Pelargonium graveolens. Barajas (2001) observed that incubation increased N, C and P mineralization in soils amended with tannery sludge. Heavy metals and micronutrient content increased in direct proportion to the quantity of tannery sludge added to the field. The concentration of heavy metals in soil was in the following order: Cr4Pb 4Ni 4Cd (Table 2). At first harvest, enhanced soil organic carbon was positively correlated with nitrogen (0.772*), height of plants (0.836*), herb yield (0.83*) and dry weight of shoots (0.753*) whereas nitrogen was positively correlated with height of plants (0.797*) and herb yield (0.719*), (Table 3).
Cr
The experiment was performed in a randomized block design (RBD). Analysis of variance (ANOVA) was used for analyzing the data and least significant differences (LSD) were calculated using the F method (Sokal and Rholf, 1981). Differences at p o0.05 were considered significant. Uptake of heavy metals and micronutrients by plant samples was calculated by multiplying metal concentration in sample with its dry weight. Linear correlation coefficients between soil nitrogen and plant height and herb yield were also analyzed.
Micronutrients conc. (ppm)
2.9. Statistical analysis
Heavy metals conc. (ppm)
Mn
GC analysis of the essential oils was carried out on a PerkinElmer Auto System XL gas Chromatograph, equipped with DB-5 capillary column (50 m 0.32 mm i.d., film thickness 0.25 mm) and flame ionization detector (FID). Identification of the essential oil constituents was done on the basis of retention time (RT) and retention index (RI). The relative amounts of individual components were calculated based on the GC peak area (FID response).
99.5 7 1.45 87.5 7 3.33 144.5 7 2.73 183.157 2.25 222 7 8.07 117.75 7 2.7 174.577 9.94 190.707 0.57
Zn
2.8. Gas chromatography analysis of essential oil
353.0 7 26.68 384.0 7 8.88 400.0 7 17.76 569.0 7 62.25 676.0 7 64.12 353.0 7 8.89 454.6 7 34.78 594.6 7 57.27
type apparatus for 2 h. Distilled essential oil was dried over anhydrous Na2SO4 and stored at 4 °C prior to analysis.
11.39 7 1.62 12.93 7 1.11 12.50 7 1.10 17.75 7 0.38 28.87 7 2.81 13.977 1.09 17.48 7 3.15 21.87 7 1.39
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0.49 70.03 0.57 70.03 0.71 70.04 0.70 70.02 0.81 70.05 0.68 70.07 0.73 70.03 0.84 70.05
298
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Table 3 Correlation coefficients between different parameters at first harvest.
OC (%) Nitrogen Height Herb yield *
Nitrogen
Height
Herb yield
Dry wt. of shoot
0.772*
0.836* 0.797*
0.83* 0.719* 0.798*
0.753* 0.585 0.71* 0.924*
Correlation is significant at 0.05 level.
production of Reactive Oxygen Species (Ghnaya et al., 2009). Hence, chlorophyll content has negative correlation with the sludge treatments. 3.3. Effect on herb yield Herb yield of palmarosa (C. martini) in all the three harvests was significantly affected by the treatment variation. Highest herb yield was recorded with 100 t ha 1 of tannery sludge application in both the cultivars of palmarosa (PRC-1 and Trishna). Similar observations were made by Singh and Agarwal (2010) on herb yield of rice at different sludge amendment rates. Among cultivars, Trishna produced higher biomass at each level (25, 50, 100 t ha 1) of sludge application than PRC-1. Biomass yield of palmarosa was recorded higher in first and third harvest as compared to IInd harvest. Lower biomass yield in IInd harvest is attributed to low temperature and relatively less availability of nutrition during October to February for crop as low temperature affects the growth of grasses adversely (Ivory and Whiteman, 1978). Trishna produced about 9.9, 16.0, 49.0% higher herb yield over its respective control, with application of 25, 50 and 100 t ha 1 sludge application, respectively in first harvest. Similar trend was observed with PRC-1 (Fig. 2). 3.4. Effect on shoot and root dry matter yield Like herb yield, variation in treatment significantly affected dry matter yield. Highest dry matter yield was recorded in T5 and T8 treatments in all the three harvests where tannery sludge was applied at the rate of 100 t ha 1. Dry matter yield was increased by 26 and 28% in T5 and T8, respectively over their respective controls in first harvest. Amendment of soil with sludge has been shown to increase the biomass and dry matter yield of crops such as forage grasses, maize, sorghum and wheat (Fresquez et al., 1991; Akdeniz et al., 2006) and aromatic crops (Patel and Patra, 2014). Among three harvests, low dry matter yield was observed in second harvest when crop was grown during November to February due to low temperature. Ivory and Whiteman (1978)
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observed that low temperature adversely affected the growth of grasses; hence dry matter yield was also negatively affected. It was again increased, when temperature raised from February last to June as indicated in third harvest. Trishna performed better at all three doses of tannery sludge applied at 25, 50 and 100 t ha 1, than PRC-1. Dry weight of roots was significantly affected with treatment variation. Root weight of PRC-1 reduced by about 48, 33 and 2% at 25, 50 and 100 t ha 1 application of tannery sludge, respectively over its control. Similar trend was followed by Trishna. At higher dose of tannery sludge (100 t ha 1) application, reduction in root weight was very low as compared to low rate of tannery sludge application in both the cultivars (PRC-1, Trishna) of palmarosa. It may be attributed to higher supply of organic carbon which is the key input to mitigate the toxic effect of heavy metals on root growth. 3.5. Effect on oil yield and quality Significant effect of variation in treatment was again observed in context to oil yield. Highest oil yield was observed in T5 and T8 treatments in which 100 t ha 1 sludge was applied (Fig. 2). There are two important constituents of essential oil of palmarosa which are known as Geraniol and Geranyl acetate. Oil quality depends upon its constituents which are further dependent on various factors such as environmental conditions, biotic stress, etc. (Patra et al., 2000). Variations in geraniol content were observed in all the three harvests but were not statistically significant. Average across all the three harvests indicated that geraniol content in PRC-1 marginally reduced at all three levels (25, 50, 100) of tannery sludge application compared to its control but it slightly increased in Trishna, over control. Geranyl acetate significantly differed in first harvest but not in second and third harvests. Average of three harvests indicated that geranyl acetate increased in PRC-1 and Trishna by 7, 11 and 25 and 6, 14 and 32% over its control, respectively at 25, 50 and 100 t ha 1 of tannery sludge application. 3.6. Status of post harvest soil Electrical conductivity, pH, organic carbon, nitrogen, phosphorus and potassium were significantly affected by treatments (Fig. 1). All these parameters including pH were reduced as compared to status of soil after 50 days incubation. Reduction in electrical conductivity may be due to leaching of soluble salts and its utilization by plants for its growth. Similarly, mineralization of organic carbon as a result of high temperature and humidity may be responsible for reduction of carbon content in post harvest soil. Nitrogen, phosphorus and potassium reduced by 25–56% over its
Fig. 1. Soil status at three different time intervals (initial, after 50 days incubation and after harvest).
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Fig. 2. Herb yield (t ha 1) and oil yield (l ha 1) in three consecutive harvests in all eight treatments of palmarosa.
application than PRC-1, respectively. Nickel uptake varied from 1.17 to 3.62, 0.2 to 0.39 and 0.035 to 0.122 kg ha 1, in first, second and third harvest, respectively. Uptake of nickel gradually decreased from first to third harvest which is due to reducing concentration of this element in soil. Total of all the three harvests indicated that Ni uptake in PRC-1 was 33, 106 and 160% higher with application of 25, 50 and 100 t ha 1 sludge, respectively over control. The corresponding increase in Trishna was 30, 118, and 137% respectively, over control (Table 4a). Results indicated that maximum Pb uptake in shoot portion occurred in first harvest, followed by third and minimum uptake was observed in second harvest. This may be attributed to less herb yield during second harvest as compared to other two harvests due to unfavorable weather conditions. Uptake varied from 1.4 to 5.22, 0.05 to 0.26, 0.02 to 0.15 kg ha 1 in first, second and third harvest respectively, Table 4(a).
initial status, in post harvest soil. Treatment variation significantly affected the chromium, nickel and lead content in postharvest soil and these ranged between 2.95–60.5, 1.38–2.60 and 3.62– 9.85 ppm respectively. Magnitude of chromium content was higher followed by lead and nickel. However, concentration of all three metals was lower than the concentration after 50 days incubation. Like metals, iron, copper, manganese and zinc content in post harvest soil was also recorded lower as compared to initial content in soil. A comparison between status of initial, at 50 days incubation and post harvest soil has been shown in Fig. 1. 3.7. Assessment of phytoremedial potential of two cultivars of palmarosa Accumulation of trace metals by plants determines both micronutrient content and heavy metal concentration. Various complex transport and chelating activities control rates of metal uptake in plants.
3.7.2. Micronutrients uptake Maximum iron uptake was recorded in first harvest followed by third and second in all treatments. Iron uptake increased by 11, 12 and 13 times in PRC-1 and 10, 11, and 12 times in Trishna with application of 25, 50 and 100 t ha 1 of tannery sludge, respectively over their control, in first harvest. Lowest uptake of iron was observed in second harvest. It may be attributed to minimum herb yield among all three harvests. Manganese uptake was recorded highest in first harvest but it was almost same in second and third. Total of three harvests indicated that Trishna has higher uptake of manganese as compared to PRC-1 at 25, 50 and 100 t ha 1 of tannery sludge application. Zinc uptake varied from 20.03 to 28.73, 0.44 to 0.93 and 0.32 to 1.23 kg ha 1 in first, second and third harvest respectively. Cumulative uptake of three harvests exhibited that Mn uptake increased in PRC-1, 13, 14, and 25% and in Trishna 11, 20 and 38% at 25, 50 and 100 t ha 1 of tannery sludge application, respectively. Maximum copper uptake was recorded
3.7.1. Heavy metal uptake in shoot portion Uptake of heavy metals was calculated by multiplying metal concentration with dry matter and the order of uptake was observed as Cr4Pb 4Ni 4Cd (Table 4a). Similar observations were made by Gupta and Sinha (2006) in Sesamum indicum and Gupta and Sinha (2007) in Brassica juncea. Total chromium uptake of three harvests of palmarosa crop, indicated that it ranges from 4.88 to 18.33 kg ha 1 during one year of crop growth. Maximum Cr uptake was recorded in first harvest followed by second and third. Although dry matter was lowest in second harvest but higher uptake may be attributed to high concentration of chromium during second harvest. Trishna has higher uptake of chromium than PRC-1. Chromium uptake in Trishna was observed to be 40, 32, and 11% higher at 25, 50 and 100 t ha 1 of tannery sludge Table 4 (a): Heavy metal uptake (kg ha 1) in shoot portion in three consecutive harvests. Treatments
T1 T2 T3 T4 T5 T6 T7 T8 CD (5%)
Cr
Ni
Pb
Cd
I
II
III
I
II
III
I
II
III
I
II
III
1.75 2.48 4.52 5.90 8.90 6.90 7.25 8.85 1.34
1.56 1.90 2.83 3.19 4.88 3.52 4.64 5.56 0.83
1.57 1.64 1.39 2.62 2.71 1.84 3.57 3.92 0.588
1.17 1.47 1.62 2.63 3.30 1.94 3.28 3.62 0.59
0.20 0.24 0.21 0.23 0.31 0.27 0.36 0.39 0.062
0.035 0.038 0.041 0.047 0.056 0.049 0.079 0.122 0.047
2.039 3.224 1.485 2.398 5.214 2.033 3.811 3.128 1.232
0.051 0.022 0.125 0.262 0.056 0.056 0.132 0.059 0.048
0.063 0.054 0.139 0.081 0.083 0.156 0.109 0.029 0.058
0.478 0.439 0.446 0.789 0.929 0.575 0.562 0.599 0.177
0.003 0.004 0.004 0.007 0.008 0.005 0.006 0.008 0.042
0.086 0.102 0.091 0.076 0.079 0.071 0.098 0.085 0.022
*All the values are mean of triplicates.
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Table 4 (b): Heavy metal and micronutrient uptake (kg ha 1) in root portion. Treatments
Heavy metals
T1 T2 T3 T4 T5 T6 T7 T8 CD (5%)
Micronutrients
Cr
Ni
Pb
Cd
Fe
Mg
Mn
Cu
Zn
0.446 0.698 1.269 0.422 0.784 1.272 1.187 1.267 1.003
0.103 0.091 0.088 0.046 0.066 0.116 0.088 0.052 0.059
0.023 0.013 0.017 0.019 0.012 0.012 0.011 0.010 0.013
0.001 0.003 0.005 0.007 0.005 0.005 0.005 0.007 0.005
17.39 11.578 10.40 9.138 9.201 10.808 9.305 6.246 6.378
9.758 7.55 6.806 4.885 5.281 6.935 6.869 4.080 4.039
0.332 0.237 0.233 0.178 0.194 0.241 0.195 0.128 0.140
0.235 0.345 0.338 0.156 0.199 0.112 0.082 0.198 0.161
0.186 0.076 0.177 0.147 0.128 0.138 0.208 0.141 0.116
*All the values are mean of triplicates.
Table 5 (a): Bioconcentration Factor (BCF) and Translocation Factor (TF) of heavy metals and micronutrients of two cultivars of palmarosa at different rates of tannery sludge application. Treatments
T1 T2 T3 T4 T5 T6 T7 T8
BCF
TF
Cr
Ni
Pb
Cd
Fe
Cu
Mn
Zn
Cr
Pb
Ni
Cd
Fe
Cu
Mn
Zn
28.42 38.24 2.03 1.28 1.13 1.08 1.67 1.52
132.86 62.95 52.03 44.62 11.45 72.42 46.32 1.65
1.22 1.49 2.35 2.02 1.02 1.43 1.12 1.09
0.15 1.77 2.34 14.82 1.72 1.25 1.60 2.90
4.81 4.01 3.99 4.57 3.04 2.78 2.61 1.89
37.06 107.93 48.67 23.80 7.79 15.53 7.04 12.84
0.92 0.75 0.88 0.89 0.76 0.66 0.58 0.56
5.10 5.13 5.28 4.07 1.53 2.81 3.43 2.63
0.07 0.05 0.01 0.01 0.03 0.08 0.04 0.02
0.37 0.25 0.47 0.24 0.55 0.92 0.71 0.19
0.06 0.03 0.05 0.06 0.06 0.08 0.03 0.13
0.05 0.004 0.04 0.002 0.004 0.008 0.008 0.003
0.19 0.09 0.49 0.09 0.29 0.11 0.12 0.22
0.05 0.02 0.03 0.04 0.04 0.12 0.15 0.05
0.25 0.26 0.31 0.24 0.27 0.31 0.28 0.23
0.33 0.52 0.34 0.36 0.55 0.75 0.49 0.48
Table 5 (b): Bioaccumulation factor (BF) of heavy metals in two cultivars of palmarosa at different rates of tannery sludge application. Treatments
T1 T2 T3 T4 T5 T6 T7
I
II
III
Cr
Ni
Pb
Cd
Cr
Ni
Pb
Cd
Cr
Ni
Pb
Cd
4.29 6.2 0.043 0.035 0.01 0.12 0.03
2.67 1.75 1.39 1.09 0.77 1.80 0.61
1.18 1.49 1.27 0.93 0.67 1.92 1.02
11.94 8.22 0.92 0.84 0.32 0.92 0.48
0.57 0.69 0.039 0.019 0.01 0.07 0.03
7.66 5.29 5.77 5.12 2.68 5.01 5.65
0.61 0.82 1.36 1.97 0.39 0.47 0.92
2.16 1 0.36 0.22 0.19 0.65 0.26
1.89 1.98 0.02 0.01 0.003 0.08 0.03
8.57 1.62 2.86 2.77 0.64 5.60 1.50
0.45 0.38 1.10 0.49 0.31 1.31 0.48
0.007 0.007 0.011 0.041 0.003 0.010 0.013
in first harvest followed by second and third in all treatments. Trishna has higher uptake of copper as compared to PRC-1 in all treatments. 3.7.3. Heavy metal uptake in roots The order of heavy metal uptake was Cr4 Ni4Pb 4 Cd in root of palmarosa and micronutrient uptake showed following order: Fe4 Mg 4Cu 4Mn 4Zn, Table 4(b). Translocation factor (TF), Bioconcentration factor (BCF) and Bioaccumulation factor (BF) are important in identifying plants suitable for phytostabilization. Plants with TF o1 and BCF 4 1 are taken as potential phytostabilisers as most of the metals get accumulated in their root portion with a very little translocation to the aerial parts (Mendez and Maier, 2008). 3.8. Translocation factor (TF) Ability of plants to translocate heavy metals from root to shoot is measured by calculating TF. Here, TF o1 was observed for each heavy metal. Hence it shows that only a meager translocation of
metals took place from root to shoot. High accumulation of heavy metals in roots may be ascribed to complexation of heavy metals with sulphydryl groups resulting in less translocation of heavy metals to shoots (Singh et al., 2004), Table 5(a). 3.9. Bioconcentration factor (BCF) It is the ratio of concentration of metals in roots to that in soil. BCF4 1 was observed for all heavy metals. Greater accumulation of heavy metals occurred in root portion of palmarosa. Thus, our test indicates that the crop can tolerate heavy metal toxicity and can grow well in multi-metal contaminated soil, Table 5(a). 3.10. Bioaccumulation factor (BF) It is the ratio of metal concentration in shoots to concentration in soil. By calculating BF of all trace elements for all the three harvests, it came out to be less than their control. It indicated that, heavy metals were not accumulated from soil in the aerial parts of plant. Moreover, BF is highest at low concentration of sludge
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application and decreased with increasing concentration, (Suter et al., 2000, Greger, 2004), Table 5(b).
4. Conclusions Our present study indicated that tannery sludge improved the fertility of soil; hence herb, dry matter and essential oil yield of palmarosa increased significantly. Moreover, cultivar Trishna proved to be better than PRC-1 in all aspects. TF o1 and BCF 41 were observed for all heavy metals, hence it can be concluded that palmarosa can be adopted as a putative candidate for phytostabilisation, in heavy metal rich tannery sludge treated soil.
Acknowledgements The authors are thankful to the Director, CIMAP, Lucknow, India, for providing the necessary facilities during the course of this investigation. Thanks are also due to CSIR, New Delhi for financial assistance through Network Project ‘INDEPTH’.
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