Improvement of Germination in Retama Sphaerocarpa and Ziziphus Lotus for the Rehabilitation of Degraded Rangelands in Algeria

Abstract

Abstract The shrubs of Retama sphaerocarpa (Fabaceae) and Ziziphus lotus (Rhamnaceae) form populations in the Aurès region of Algeria that can provide a large supply of forage when dry season grazing shortages are prevalent. However, the percentage of natural regeneration of these species was estimated at 3%-7%. The final germination percentage (FGP) and total seedling length (TSL) were taken into consideration in this study to determine the impact of wet scarification on the germination of these two species. Pre-sowing treatments included immersion in concentrated sulphuric acid for 1, 2 and 3 hours; immersion in boiling water for 15 minutes, and soaking for 24 hours in water at 25°C (± 2°C). For each pretreatment, four replicates of 50 seeds and kernels were sown in plastic containers for a 21-day period. The principal component analysis of data showed that the best treatment was 3 hours of soaking in sulphuric acid, resulting in 94% of FGP and 22.2 cm of TSL for R. sphaerocarpa. This same pretreatment improved the germination of Z. lotus to 86% FGP and 25.6 cm TSL. In both species studied, a very insignificant percentage of FGP (2%) was observed in untreated seeds and kernels, as well as in pre-treatments with water. These results indicate that R. sphaerocarpa seeds and Z. lotus kernels exhibit a type of physical seed dormancy and require specific pretreatment to improve imbibition and germination. In conclusion, pretreatments significantly (p< 0.0001) affected FGP and TSL in both species. These findings should motivate plantation plans for R. sphaerocarpa and Z. lotus in both agriculture and forestry.