PHYSIOLOGICAL STUDIES ON GERMINATION AND FERTILIZATION OF SOPHORA PLANT. 1- ENHANCING GERMINATION OF MESCAL BEAN (Sophora secundiflora) SEEDS HARD–TO-GERMINATE.

Abstract

The seeds of Mescal-bean (Sophora secundiflora) have an extremely hard red shells and can take years to germinate. The current study was undertaken to break the physical dormancy of such seeds under semi-shade at the nursery of AlZohriya Garden, Hort. Res. Inst., ARC, Giza, Egypt, during 2017 and 2018 seasons by subjecting them to some pre-sowing treatments includeing untreated seeds (control), soaking in tap water for 48 h. at room temperature, soaking in hot water (60-70C) for 48 h (thermal scarification), rasping with a file (mechanical scarification), rasping + soaking in tap water for 24 h. (combined treatment) and soaking in concentrated sulfuric acid (98.5 %) for 1, 2 or 3 h. (chemical scarification). The seeds were sown in 16-cm-diameter plastic pots (10 seeds/pot) filled with about 1.5 kg of an equal mixture of sand and clay (1:1, v : v). The results indicated that the highest germination percentage (G%) and the least No. days to either 50 % germination or higher were achieved by soaking in hot water for 48 h treatment in both seasons, while control and all other treatments failed to increase G % to 50 % in both seasons. The best germination rate index, vigour index, seed viability and epicotyl length were also attained by hot water treatment. Soaking the seeds in tap water for 48 h. under room temperature did not affect the amount water uptake by the seeds, while other treatments greatly affected this parameter, as the greatest amount of water was taken up by the seeds rasped with a file or soaked in concen. H2SO4 for 3 h. treatments followed by soaking the seeds in hot water. However, the former treatments made the seeds absorb the maximum amount of water in the first 24 h., and this amount was steady afterwards, whereas the latter made water absorption continuous till the end of soaking time. A similar response occurred as well in respect of seedling vegetative and root growth measurements and the leaf content of pigments, total soluble sugars and indoles, as hot water treatment gave the utmost high means at all. In addition, the different treatments induced a marked decrement in the concentration of phenols , where the greatest decrement was also recorded by the hot water treatment. From the foregoing, it can be recommended to soak seeds of Mescal-bean (Sophora secundiflora) tree in hot water (60-70C) for 48 h. to score the best germination and seedling growth.