PJB-2013-332
PHYSIO-MORPHOLOGICAL RESPONSES OF NATIVE ACACIA NILOTICA TO EUCALYPTUS ALLELOPATHY
F.A. BUGHIO1*, S.M. MANGRIO1, S.A. ABRO1, T.M. JAHANGIR2 AND HADI BUX1
Abstract
Allelopathic effects of exotic Eucalyptus camaldulensis Dehnh. have been widely reported and are considered the major factor limiting the establishment of native tree species in local forests. A lab study was conducted to investigate the allelopathic effects of Eucalyptus camaldulensis on native trees and Acacia nilotica was selected as bioassay plant. Since Eucalyptus leaf litter enters in the soil environment either in the form of solid matter or as aqueous extract. The allelopathic impacts of these two forms were assessed in laboratory experiment conducted at Green House of Institute of Plant Sciences, University of Sindh, Jamshoro, Pakistan. In a pot experiment the leaf litter was applied in total 6 concentrations along a control, no leaf litter. The three concentrations of ground solid leaf litter were mixed with soil in 10, 20 and 30%. Similarly, the aqueous stock solution of 1:20 was prepared and dilutions were made in 10, 20 and 30%. The plant parameters such as percent germination, relative germination ratio (RGR), percentage mortality rate (MR), seedling vigour index (SVI), chlorophyll content (mg/g f. wt.), relative elongation of shoot (RERs), relative elongation of root (RERr), relative biomass ratio (RBR), fresh and dry weight (g) was calculated. Soil samples were taken from laboratory experiments and analyzed for pH, soil salinity, organic matter, N, P, K, and Na. Results suggest that Eucalyptus leaf litter and leaf litter aqueous extract significantly reduced the frequency of percent germination and relative germination ratio, Eucalyptus leaf litter show high mortality rate than leaf litter extract, reduced seedling vigour index, chlorophyll content, relative elongation of shoot and relative elongation of root, also reduced the fresh and dry weight of the plant. The soil pH decreased with increasing concentration and soil salinity increased with increasing the concentration. While organic matter, nitrogen, phosphorus and potassium concentrations increased in soil with increasing concentration. The solid leaf litter was found more dangerous than aqueous extracts.
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