Studies on the effect of different polluted soil on the growth performance of Cajanus cajan L.

The study examined the effect of different polluted soils on the emergence and growth performance of Cajanus cajan L. The experiment was conducted in a screen house under controlled environmental conditions. Different polluted soils obtained from, mechanic workshop (PSM), garbage soil (PSG), soil near power generator (PSP), laundry site (PSL), vehicular roadside (PSR) and soil devoid of pollution (UPS) serves as control. The percentage emergence of the seeds, height, stem girth, number of leaves, leaf area and relative growth rate (RGR) were studied to determine the growth performance of C. cajan. The result of the study revealed that the emergence of seeds, heights, stem girth, number of leaves and leaf area of C. cajan were mostly reduced in soils derived from PSM, PSP and PSR which are believed to have higher concentrations of crude oil contamination. The plant height at 8 weeks after planting (WAP) was lowest in PSM soil (28.18±2.15 cm), PSP soil (85.66 ±3.46 cm), PSR soil (92.18±4.28 cm) while control soil (UPS) had the tallest plant (124.78±3.76 cm). Leaf area at 8WAP in PSM soil was 1.32±0.28 cm2, PSP soil (2.81±0.29 cm2), PSR soil (2.59±1.37 cm2) and PSL soil had leaf area of 4.05±9.06 cm2. C. cajan had lowest mean number of leaves in PSM soil with 5.80±1.48. The relative growth rate of C. cajan was also reduces in PSM soil (0.05±0.01), PSG soil (0.06±0.03) and PSR soil (0.09±0.02) while the plant on control soil (UPS) has 0.20±0.02. Statistical analysis (ANOVA, P≤0.05) showed that significant differences abound in the percentage emergence of seeds, plant heights, number of leaves, leaf area and the relative growth rate. Soil contaminated with crude oil are prone to reduction in soil aeration and microorganisms which have resultant effect on the growth of this plant. The effluent of spent crude oil on agricultural soils should be prevented to avert the reduction in the growth of agricultural crops.