Provenance Variation in seed germination, early seedling growth and water consumption of Hashab (Acacia senegal) on Clay Soils of Sudan

Abstract

The aim of this study is to assess the variability and differences in seed germination, early seedling growth and water efficiency among Acacia senegal provenances from the central clay plains of Sudan. Twelve locations throughout the clay part of the gum belt were identified as seed sources according to geographical discontinuity and differences in annual rainfall. Three irrigation intervals (every three, six and twelve days) were applied. To estimate the transpiration rate three bags in each cemented bed were kept without seedling and treated like the other bags in the same bed containing seedlings. All bags were weighed before and after irrigation allowing 5 minutes for drainage of excess irrigation water. Transpiration was calculated according to the irrigation treatments schedules from the differences in water loss between the bags with plants and those without plants. The irrigation interval had significant effect on germination percentage and seedling growth. The root/shoot ratio increased with the prolonged irrigation schedule. This indicated that the seedlings have tendency to allocate more dry matter to the root system and increase its growth and biomass as an adaptation against the dry soil conditions. However, there were some significant differences on the growth parameters in the interactions between the irrigation treatments and the hashab provenances. Most of the provenances showed close transpiration rate with some exceptions. The water use efficiency of the seedlings from the different provenances also varied and showed significant differences. This study concludes that seedlings of Acacia senegal have variability in growth performance. Also the seedlings growth is checked by the moisture availability in the soil and seedlings with high drought tolerance maximize the use of the moisture to build their biomass.