Mechanical scarification: The key to optimal germination parameters in nine flowering species of the United Arab Emirates

Abstract

Seed germination is the most essential stage of the plant life. Prior to germination, seed dormancy provides protection to the seed against germinating under unfavorable conditions. The seeds of many plants in arid regions are particularly characterized by having a hard seed coat. Seed dormancy is essential to the survival of plants, however in some incidents such as reforestation on desert areas, it is important for ecologists to investigate methods of breaking the dormancy of seeds in order to maximize the production of plants. In this study, we tested four methods of seed pre-treatment (Mechanical scarification (MChip), chemical scarification with sulfuric acid at two exposure durations (SAcid15, SAcid30), and soaking in water for 24 h (Soak)) on 9 flowering plants (Senna italica, Sorghum sudanense, Tephrosia nubica, Senna angustifolia, Acacia tortilis, Senna occidentalis, Abutilon pannosum, Prosopis cineraria, Crotalaria persica) of the UAE. Six germination parameters (Final germination percentage (G) %, Mean germination time (MGT) day, Mean germination rate (MGR) day, Coefficient of velocity of germination (CVG) %, Mean Daily Germination Percentage (MDG) %, and Germination index (GI) day) were calculated to assess the germination. Final Germination Percentage (G) significantly improved (P < 0.005) in seven species (100% in S. italica, 98% in S. sudanense, 97% in T. nubica, 99% in S. angustifolia, 98% in A. tortilis, 99% in P. cineraria, and 93% in C. persica) with Mchip and SAcid30 (1.124% in S. italica, 28% in S. sudanense, 3% in T. nubica,82% in S. angustifolia, 96% in A. tortilis, 99% in P. cineraria, and 25% in C. persica), three species (1.562% in S. italica, 28% in S. sudanense, 3% in T. nubica, 62% in S. angustifolia, and 62% in P. cineraria) with (SAcid15), and only two species (3% in T. nubica and 5% in A. tortilis) with Soak. S. occidentalis was the only species that did not show significant changes in germination parameters after each treatment. Mechanical scarification is the safest and most affective pretreatment method according to our findings.