EFFECT OF HEAVY METALS ON MORPHOLOGICAL AND BIOCHEMICAL CHARACTERISTICS OF Salix alba L. SEEDLINGS
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Date
2015
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ABSTRACT
The investigation entitled “Effect of heavy metals on morphological and biochemical characteristics of Salix alba L. seedlings” was carried out at the Research Farm of Department of Environmental Science of College of Forestry, Dr Y S Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh during 2014- 2015. In order to study the effect of heavy metals viz. Cd and Hg on morphological and biochemical parameters and their uptake in Salix alba seedlings, pot experiment was conducted on one-year-old cuttings. Experiment was laid out by imposing 16 treatments composed of various combinations of graded levels of Cd and Hg at 0, 5, 10 and 20ppm. The treatments were replicated four times in Completely Randomized Design.The observations on morphological, biochemical parameters, buildup of Cd and Hg in soil and their uptake in Salix alba seedlings were recorded. The graded doses of Cd and Hg and their interaction exerted significant influence on the morphological parameters like number of leaves, branches, stem diameter, root- shoot ratio, root dry weight and total biomass. Number of branches reduced in the order of 20 ppm> 10 ppm> 5 ppm of Cd levels. The effect of Cd in reducing seedling height followed the order 20ppm (23.6%) > 10ppm(18.4%)> 5 ppm (6%). Stem diameter decreased with increase in heavy metal doses in the order 20 ppm> 10 ppm> 5ppm. There was an increase in root dry weight and total dry biomass uptill 10 ppm Cd dose but at higher levels of 20 ppm these parameters decreased slightly. Root-shoot ratio varied significantly between 0.29-0.70. Biochemical parameters like chlorophyll and total sugar content in leaves decreased with increasing level of Cd and Hg. Leaf phenol content was in the range of 12.91 to 16.78 mg g-1 under Cd and 13.39 to 16.45 mg g-1 under Hg and increased with increasing level of Cd and Hg. The soil microbial activity under the graded doses of Cd and Hg was in the range of 96.59 to 63.06 mg kg-1 under Cd and 78.94 to 73.24 mg kg-1 for Hg and followed a decreasing trend with increasing levels. The leaf Cd and Hg content range from 0.15 to 0.49 mg kg-1 to 0.09 to 0.29 mg kg-1, respectively. The soil buildup of Cd and Hg was in the range of 0.65 to 7.62 mg kg-1 and 0.87 to 12.75 mg kg-1 respectively which was higher than the permissible limits. Cd and Hg in soil exhibited positive significant correlation with their concentration in leaves of Salix alba seedlings. Increase in Hg and Cd uptake was observed with increase in heavy metal concentration with values ranging between 0.019 – 0.054 mg/plant and 0.010- 0.046 mg/plant for Cd and Hg respectively. Salix alba seedlings tended to survive uptil 20 ppm Cd and Hg concentration and had a good ability of accumulating these metals.