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Sudan Journal of Agricultural Research

Allelopathic effects of Eucalyptus and Conocarpus plantations on germination and growth of two sorghum species.


E. E. Ibrahim, H.A. Mohamed and A. F. Mustafa

Abstract:

Allelopathic effects of Eucalyptus camaldulensis Dehn, and E. microtheica Muell. leaf and litter extract on seed germination of Sorghum hicolor (L) Moench (Abu sabeen, Gadam elhamam and Milo) and Sorghum sudanense (piper) Stapf (Sudan grass) were investigated under laboratory conditions. Effects of both species in addition to Conocarpus lancifolius on sorghum dry matter production was also studied under field conditions at Kassala and Fawar during the season 1991/92. Eucalyptus leaf and/or litter extracts significantly reduced germination % of sorghum seeds when applied at high concentration and/or when leaves and litter were soaked for long periods in water (p < 0.05). On the other hand, differences in germination% of sorghum species planted in soil samples collected from bare soil (Control) and Eucalyptus plantation soil were not significant. Results offield experiments showed that there were no significant differences in dry matter production of the two sorghum species between completely felled Eucalyptus and Conocarpus plantations (residue containing) and the control (residue free) plots in both Kassala and Fawar areas.
On the contrary, partially felled Eucalyptus and Conocarpus plantations significantly depressed dry matter production relative to the control and the completely felled treatments ( p < 0.05 ). These differences were attributed to a significant reduction in the amount ofintercepted solar radiation by Sorghum spp. in partially felled plots.

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Sudan Journal of Agricultural Research Vol. 2(1999) PP. 9-13