Kumar and Saritha

to the weed plants. The P, K and N help the plants in up taking the metals in

bounded forms. Soil particles are sandy and slightly acidic in both control and

contaminated soils. Compared to control soils organic carbon (0.23±0.22) and

phosphorous content (0.41±3.29) decreased in contaminate soils (0.13±0.35)

(0.33±0.15) but nitrogen (55±2.26) and potassium contents (65±1.27) increased

(68±1.20) (72±0.03) (Table 1).

Physical and chemical properties of soil

table 1: Physical and chemical properties of soil

Parameters

control Soil

contaminated soil

Soil Texture

Sandy loam

Sandy loam

Soil PH

5.7±0.05

5.2±0.08

Organic Carbon (gm/kg)

0.23±0.22

0.13±0.35

Available N (gm/kg)

55±2.26

68±1.20

Available P (gm/kg)

0.41±3.29

0.33±0.15

Available K (gm/kg)

65±1.27

72±0.03

Total Pb (mg/kg)

1.27 mg/kg

164.5 mg/kg

Effect of Pb on chlorophyll content

Chlorophyll content in plants is important factor in determining photosynthetic

activity. In our present study, heavy metal Pb decreased chlorophyll content

gradually by increased proportionality of metal concentration. Pb significantly

effected phototosynthetic pigments (chlorophyll a and chlorophyll b) in weeds.

Chlorophyll-acontentwasdecreasedfrom62%to34%inallplantswhencompared

to controls with high decline in Anisomilius molabarica (62%), Ipomea purpurea

(52%) and Eichornia fasculata (52%) followed by Parthenium histocarpus (47%),

Calotropis procera (34% ) and Bromus tectorum (40%) in comparision with

controls (Fig. 1). Chlorophyll-b decreased from 81% ( Bromus tectorum ) to 36%

( Calotropis procera ) in all plants followed by Ipomea purpurea (76%), Anisomilius

molabarica (75%), Parthenium histocarpus (63%) and Eichornia fasculata (56%)

in comparision with controls (Fig. 2). The content of chlorophylls a, b chlorophyll

was significantly decreased corroborates with findings of Salvinia minima wild by

Jeffrey l. Gardner and Safaa h. al-hamdani (1997) and Zengin and Munzuroglu

(2005) in phaseolus vulgaris L due to Pb stress. Decreased chlorophyll content

associated with heavy metal stress may be the result of inhibition of the enzymes

responsible for chlorophyll biosynthesis.

16

Int. J. Bioinformatics and Biological Sci.: v.2 n.1&2, p. 13-22. March & June 2014