EFFECTS OF SHORT-TERM EXPOSURE OF SIMULATED ACID RAIN ON THE GROWTH OF <em>ACACIA</em> <em>NILOTICA</em>

Abstract

BALASUBRAMANIAN, G., UDAYASOORIAN, C. & PRABU, P. C. 2007. Effects of short-term exposure
of simulated acid rain on the growth of Acacia nilotica. The response and measurable effects of simulated
acid rain at different pH levels of 3.5, 4.5, 5.5, 6.5 and 7.0 on Acacia nilotica seedlings grown on black and
red soils were investigated for six months. A set of 10 potted seedlings in each treatment was exposed
to 15 min foliar spray of 125 ml simulated rain acidified with sulphuric and nitric acids at a ratio of 2:1.
The simulated rain was sprayed in 10 spells from 45−70 days after planting. The study was conducted in
the non-monsoon season to exclude ambient rain. Increasing acidity of simulated acid rain resulted in a
general decrease in all growth characters of seedlings in both soils, namely, plant height, root length, leaf
number, total dry matter accumulation, leaf dry weight, stem dry weight, root dry weight, leaf area, single
leaf size, specific leaf area, leaf area index, leaf area ratio and crop growth rate. However, A. nilotica on red
soil showed deleterious morphological and growth characters when exposed to simulated rain at pH 3.5
compared with those on black soil.