Abstract:
In this study two experiments were conducted at Environmental and Natural Resources Research Institute nursery at Khartoum during the period from mid- October 2004 to mid- June 2005, to study the effect of salt stress ( irrigation with saline water and soil salinity) on three acacia species Acacia seyal, Acacia mellifera, Acacia tortilis and Eucalyptus camaldulensis. The experiments were conducted under nursery conditions with no control of temperature and no supplementary lightings.
In the first experiment (irrigation with saline water) seedlings were irrigated with water containing five levels of sodium chloride (0, 250, 500, 1000, and 1500 mg l-1) for three months. In the second experiment the same soil used in the first experiment was reused again. However, the soils have different EC values resulting from irrigation with saline water. Growth parameters measured included stem elongation every two week and root length and shoot and roots dry weights at the end of the experiment.
Results obtained showed that salt stress significantly decreased plant growth (stem elongation) in all plants species. The degree of reduction in growth increased with increasing NaCl concentration in the irrigation water and soil salinity. Although, irrigation with saline water and soil salinity significantly reduced stem elongation, plants seedlings survived and continued to grow throughout the experiment period. Root and shoot dry weights were significantly reduced by salt stress. The degree of reduction was greater in shoots than in roots in all plant species and different salt concentrations. Among Acacia species Acacia tortilis and Acacia mellifera were more tolerant to salt stress than Acacia seyal. Result of this experiment revealed that Acacia seyal is sensitive to salinity. Eucalyptus camaldulensis showed moderate response to salt stress. For afforestation and reforestation in arid land Acacia seyal is not recommended in saline soils. The other Acacia species and Eucalyptus may introduce in moderately saline conditions.
