Changes in allelopathic potential in relation to incubation conditions of soil mixed with Acacia pubescens (Venten.) leaf powder
1999
Kitou, M. (Kobe Univ. (Japan). Faculty of Agriculture)
Water extract of Acacia pubescens leaves inhibited the germination of lettuce seeds. The effect of the water extract disappeared during a shorter period of incubation of the soil-leaf powder mixture (sample) under 60% MWHC (maximum water holding capacity) at 25 degrees C. Further incubation of the samples led to a stimulation of root elongation. The stimulatory effect of the water extract on root elongation thereafter gradually decreased and disappeared by the 35th day of incubation. Water extracts of samples incubated under 60% MWHC but at 5 degrees C continued to display an inhibitory effect on germination up to 35 days of incubation and did not show any stimulatory effect on root elongation. The stimulatory effect on root elongation was not distinct in the samples incubated under 120% MWHC at 25 degrees C. Samples incubated under 30% and 60% MWHC at 25 degrees C showed similar characteristic effects, but a longer period was required for the disappearance of the inhibitory effect on germination in the samples incubated under 30% MWHC. The soil temperature thus appeared to have a stronger influence than the soil water content on allelopathic effect of soil mixed with leaf powder of A. pubescens. The variations in the characteristic allelopathic effects of water extracts in relation to the incubationperiod of the mixture of soil and leaf powder were related to the pH and EC values of water extracts
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