The Effect of Simulated Acid Rain on Plant Growth Component of Cowpea (Vigna unguiculata) L. Walps

The rain forest belt in Southern Nigeria is potentially susceptible to problems related to acid rain because of the increase in the consumption of petroleum oil products, such as diesel, gasoline and coal, used to produce energy for different sectors of the economy. The effect of simulated acid rain on the plant growth component of cowpea, Vigna unguiculata was studied. A greenhouse experiment was conducted at the Federal University of Technology, Akure, Ondo state, Nigeria. Simulated acid rain was prepared with a mixed concentrated sulphuric acid (H_2SO_4) and concentrated nitric acid (HNO_3) in a ratio 2:1 to get the desired pH using a Deluxe pH meter. The plant was exposed to simulated acid rain of pH 2.0, 3.0, 4.0, 5.0, 6.0 and 7.0 which was the control. Simulated acid rain induced morphological changes including chlorosis, early leaf senescence, necrosis, leaf abscission, leaf folding and death. Plant height, leaf area, fresh weight, relative growth rate, chlorophyll content of the leaf and harvest index were highest at 7.0 (control) but significantly (p 0.05) decreased with increasing the acidity levels. V. unguiculata was seriously affected by the simulated acid rain.