Effect of different treatments and light quality on Ulmus pumila L. germination and seedling growth

Abstract Ulmus pumila L. has potential benefits for erosion control, landscape ornamentals, and the bark contains substances that may have therapeutic value. To determine optimal growth conditions, we investigated the effect of water, sucrose, and exogenous plant growth regulator (6 benzylaminopurine: BA, indolebutyric acid: IBA and gibberellic acid: GA3) treatments as well as light quality (dark, fluorescence, and 2:1 or 4:1 Red:Blue (R:B) LED) on U. pumila seed germination and seedling growth. Seeds soaked in a 3% sucrose solution had the highest germination rate and germination energy in addition to the shortest germination time compared to seeds treated with water or PGRs, except the control. Light quality only affected germination energy, with seeds exposed to 2:1 R:B LED light having the highest germination energy and those exposed to fluorescent light having the lowest. Following transfer to a greenhouse with exposure to natural sunlight, the performance of seedlings varied depending on the light conditions under which they were germinated. In contrast, treatments during the germination stage such as incubation with PGRs had no effect on seedling growth in the greenhouse. Seedlings that germinated under 2:1 or 4:1 R:B LED lights grew taller and had thicker root collars compared to those grown in the dark or under fluorescent lights. The influence of light conditions persisted for at least seven months after the germination, even though the chlorophyll content was similar among seedlings exposed to different growth conditions. Taken together, these results show that light quality in particular during the germination stage can positively affect the growth of the U. pumila seedlings.