Chemical Methods to Improve Seed Germination and Seedling Growth of Honey Locust (Gleditsia triacanthos L.)

The present study aimed to improve the seed germination and plantlet development of honey locust (Gleditsia triacanthos) using two types of edaphic substrate (peat and peat+sand) and different chemical substances. Breaking physical dormancy for some forest seeds is a challenge for researchers and forest managers in order to obtain a homogeneous germination on larger areas. Germination percentage of honey locust seeds were investigated by using different chemical treatments as follows: calcium hydroxide; concentrated solution of sodium 4-nitrophenolate; solution with a content of auxines; copper sulphate; potassium permanganate and concentrated sulfuric acid. The highest percentage of seed germination was obtained when the seeds were immersed in an aqueous solution of sulfuric acid (14%), followed by 12.5% (concentrated solution of sodium 4-nitrophenolate) and 12.3% (solution with a content of auxins). The lowest values (5%) were recorded when copper sulphate was used. Regarding the different types of studied substrates, the highest percentage of germination was obtained on peat + sand. As regards to seedling development, the highest values were obtained on the peat + sand substrate, with seeds treated with sulfuric acid (15.0 cm). The concentrated solution of sodium 4-nitrophenolate and solution with auxins recorded also high values, 15.2 cm, respectively 14.9 cm.  The lowest values for seedling height (11 cm) was noted when seeds were treated with potassium permanganate.