comparative assessment of the toxic effects of copper and ...

COMPARATIVE ASSESSMENT OF THE TOXIC EFFECTS OF COPPERAND CYPERMETHRIN USING SEEDS OF SPINACIA OLERACEA L.PLANTSR.K. Sharma*, S. Devi* and P.P. Dhyani***G.B. Pant Institute of Himalayan Environment and Development, Himachal Unit,Mohal, Kullu- 175 126, Himachal Pradesh, India** G.B. Pant Institute of Himalayan Environment and Development,Kosi-Katarmal, Almora- 263 643, Uttarakhand, IndiaINTRODUCTIONCopper (Cu) is one of the essential micronutrients required for the growth and development of allthe organisms at low concentration but its higher concentration, i.e. above its safe limit (Awasthi, 2000;FAO/WHO, 1999), may adversely affect the physiological and biochemical activities of both plants andhuman beings (Shan et al., 2002). The frequent use of Cu containing pesticides, fertilizers, solid waste,compost or waste water may increase its concentration in soil up to toxic levels (Singh et al., 2004; Singhand Agrawal, 2007; Singh et al., 2010). Cypermethrin (CPM), a synthetic pyrethroid, is one of theextensively used insecticides in Kullu (H.P.) to control the pests and increases productivity of vegetablecrops such as tomatoes, cabbages and cauliflowers, etc. The excess use of CPM not only leaves its residuein soil but also leads to potential pollution of soil, air and ground water (Liu et al., 2009). Cypermethrin isan active ingredient of the different formulations such as Challanger, Cypermil, Ripcord and Goldsyp(10% or 25% EC), etc. Earlier studies have shown that CPM, Cu and Cd had toxic effects on seeds ofdifferent crops (Wang and Zhou, 2006). Seed germination, root and shoot elongations have been used totest the short term phytotoxicity in plants (Wang et al., 2002). The contamination of soil by both CPMand Cu may influence the seed germination and growth of crops at their seedling stage. Therefore, aninvestigation on their toxic effects in terms of seed germination and root and shoot elongation of plants isessential. This paper highlights the comparative toxic effects of Cu and CPM at their differentconcentrations ranging from 0 - 0.05 mg ml -1 on the germination and growth responses of seeds ofSpinach (Spinacia oleracea L.) plants. Spinach is a fast growing chenopodiaceous plant, leafy in natureand rich source of nutrients (especially Fe) is commonly grown in different regions of India throughoutthe year.MATERIALS AND METHODSHealthy seeds of spinach (locally named as Palak) were soaked in 0, 0.01, 0.03, 0.05 mg ml -1concentrations of Cu and CPM (active ingredient) separately for 24 hours. The seeds were then washedwith double distilled water and dried using blotting paper. Ten seeds from the respective treatments werekept on wet Whatman filter paper no. 1 in a petridish of 90 mm diameter and covered with lids. Eachtreatment had five replicates. The petridishes were kept at 25 o C and 25W light intensity in a germinatorfor a couple of weeks. The germination of seeds was monitored and counted at 2 nd and 7 th days afterincubation. The seed germination rate was calculated using following equation:Seed germination rate (SGR) = Ln 2 -Ln 1T 2 -T 1Where, Ln 1 and Ln 2 are the percent seed germination at time T 1 and T 2 . The root and shootelongation of tested seeds were measured after two weeks of incubation. The fresh yield (roots andshoots) was also measured manually. Two-way ANOVA test was applied to the generated data to find outthe significant effects of the source variables such as chemicals, treatments and their interactions on the

tested parameters. Duncan’s multiple range test (DMRT) was further applied to the data to test thesignificant differences between the treatment means.RESULTS AND DISCUSSIONThe results showed that seed germination decreased significantly with increasing concentrationsof both the CPM and Cu (Fig. 1). The reduction in seed germination was recorded maximum at 0.05 mgml -1 treatment of both Cu and CPM (36% and 59%, respectively). The toxic effects of CPM on seedgermination was found more as compared to Cu (R 2 = -0.93, p

Fig. 3 Effects of chemical treatments (0-0.05 mg ml -1 ) on fresh yield of seedlings of S. oleracea L. Bars are mean ±SE of five replicates. Bars of respective treatment followed by different letters are significantly different from eachother at p≤0.05 (Duncan’s multiple range test).The results of two-way ANOVA test clearly showed that chemicals, treatments and chemicals ×treatments have significant effects on all the tested parameters of plant growth (Table 1). However,interaction of variables and chemicals did not show significant effects on shoot and root elongation. Thisstudy also suggests that the sources of variables and their interaction may affect the growth anddevelopment of seedlings of spinach plants. This study concludes that presence of CPM and Cu in soilmay influence the seed germination, PSG, SGR and growth of seedlings of a crop. The study furtherreveals that CPM has more toxic effects on seeds of S. oleracea L. as compared to Cu, and toxic effect orsoil pollutants on food crops needs to be studied further.Table 1: Results of two-way ANOVA test F-values (significance levels) for the tested parameters of S. oleraceaL. seeds.ParametersSources of VariationChemicals (C) Treatments (T) C × TPSG 46.10 (***) 96.70 (***) 6.12 (**)SGR 13.98 (**) 29.75 (***) 1.24 (ns)Root elongation 0.13 (ns) 43.60 (***) 7.31(**)Shoot elongation 4.47 (*) 17.68 (***) 1.05 (ns)Total yield 158.16 (***) 105.23 (***) 3.54 (*)Levels of significance; ***P

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