Efficient in vitro germination of the endangered Sinai hawthorn (Crataegus sinaica)

Abstract Sinai hawthorn, Crataegus sinaica , is a rare wild tree species of economic importance with potential for medicinal uses. The in vivo seed germination of this tree species is extremely low. The present study aimed to develop an efficient in vitro seed germination that can contribute to the successful propagation, restoration, and preservation of this critically endangered species. The study examined factors that could enhance seed germination frequency (GP) and dormancy break of mature seeds. This included stratification temperature, cytokinin type and concentration, sinapic acid (SA) concentration, gibberellic acid (GA), and substituting nutrient media with water. Cold-stratified seeds for 4 weeks at 7 °C showed highest GP of 29.3%. GP of 36% was obtained on media containing 0.5 mg/L of each 6-Benzyladenine (BA) and meta-Topolin (mTp). Low concentrations of SA increased GP (50%) in both full and ½ Murashige and Skoog basal media with Gamborg B5 vitamins (MSB5). Sterile ddH 2 O supplemented with selected combined GA, SA, and mTp treatment showed a higher GP (46%) compared to the control. The study investigated the physiology of seed maturation during late growing season and after stratification and their correlation with germination efficiency. Stratification at 7 °C increased total soluble sugars, decreased abscisic acid (ABA) content, and increased GA. This study presents the first report on seed germination in Sinai hawthorn, highlighting the importance of environmental and physiological treatments for improved efficiency. It also offers a simple, inexpensive, method for in vitro seed germination with high efficiency that may be applied in propagation and restoration.