Effect of imposed drought on seedlings growth, water use efficiency and survival of three arid zone species (Acacia tortilis subsp raddiana, Salvadora persica and Leptadenia pyrotechnica)

Abstract

Survival of seedlings in arid zone plantation is strongly affected by water stress and drought conditions. Many tree species are able to develop adaptive mechanisms in response to drought stress. The aim of this study was to assess the effect of imposed drought stress on seedlings growth, water use efficiency and survival of three arid zone species ( Acacia tortilis subsp. raddiana, Salvadora persica and Leptadenia pyrotechnica). Three successive drought cycles were imposed, to a five months old seedlings of the three species. At the end of the drought cycles treatment, water was withheld from both well watered and stressed seedlings and survival was counted until all seedlings wilted out. Growth traits and WUE were measured in drought treated and untreated seedlings. The results showed that imposed drought stress enhanced adaptive traits on these seedlings resulting in better survival. Drought treatment significantly reduced growth traits and WUE in the three species and increased root to shoot ratio and survival. The results pointed out that drought stress conditioning enhanced adaptive traits for these species. However, response was varied among species. S. persica showed better growth than A. tortilis and L. pyrotechnica, alternatively survival was better in A. tortilis and L. pyrotechnica than S. Persica. These results may suggest that in severe drought-prone sites A. tortilis and L. pyrotechnica are preferred