Impact of Various Scarification Methods and Osmotic Stress on Gleditsia triacanthos L. Seeds

Desertification is considered one of the most concerning environmental issues of the 21st century; it is a real problem for arid and semi-arid environments, where precipitation is variable and plants are subjected to more or less prolonged periods of drought. To combat desertification in Algeria, the selection of tree species for reforestation is based on specific criteria, including their tolerance to the water stress. Germination is the starting point of a plant's life cycle. It initiates the growth process. Successful germination is especially crucial in drought conditions to ensure the growth and survival of plants.

The germination of Gleditsia triacanthos L. seeds requires scarification to enhance water absorption. The seeds are divided into two lots: non-scarified seeds (control lot) and scarified seeds. The scarified seeds are further separated into different lots according to the types of scarification used: manual, microwave, boiling water, and sulfuric acid scarification. Osmotic stress is induced using polyethylene glycol 6000 (PEG₆₀₀₀), an inert substance used as an osmoticum.

Our findings indicate that the most effective scarification method for this species is manual scarification followed by exposure to a microwave (360 watts) for 90 seconds.

The addition of PEG₆₀₀₀ reduces the osmotic pressure of imbibition solutions, leading to a decline in germination rates, which are observed to be 22% and 64% at -0.55 and -1.59 bars of pressure, respectively. G. triacanthos seeds do not germinate under pressures below -3.13 bars.

Our study reveals a significant variation in the effectiveness of pre-treatments for breaking the dormancy of G.triacanthos seeds. Germination is completely inhibited at -5.17 bars, suggesting that these seeds are poorly tolerant to osmotic stress.