The features of structure changes in the shell of the Gleditsia triacanthos seed cover during germination

Background. Gleditsia triacanthos L. is a deciduous tree used in landscaping park areas. G. triacanthos is a multi-purpose tree species that produces dark brown seeds with a hard cover. The seeds have a physiological dormancy due to the hard seed cover. G. triacanthos has a high economic value, but its cultivation is complicated by the fact that the seeds germinate slowly, and seedlings appear at different times. The purpose of the study is to describe the structure of the seed cover of G. triacanthos, as well as the changes that occur in it during germination. Materials and methods. G. triacanthos has a hard seed cover. The seed coat of was studied using electron scanning microscope “Versa 3D”, an IR-Fourier spectrometer “Nicolet-6700” to study the phenomenon of hard-seeding. The cover was examined in the native state, as well as after imbibition. Results. The outer layer of the seed cover of gledichia consists of two rows of columnar cells, the cracks between which form cracks on the surface of the seed. These cells stretch, when they swollen, what leads to the growth of cracks and allows water to penetrate into the next layers. The IR spectrum analysis of the seed cover demonstrated that cellulose and lignin complex is the basis of the gledichia cover. Conclusions. The seeds of G. triacanthos have a hard seed cover and do not germinate well. Three main layers with different physico-chemical and mechanical properties were found in the seed cover of gleditsia. During the imbibition, the cracks on the outer layer increase, and a three-stage control of the swelling is observed. IR-spectrometry showed the presence of small amounts of suberin, hemicelluloses, as well as products of cellulose and lignin oxidation in the composition of the seed cover of gleditsia.