Understanding Seed Dormancy Breaking in Buchloe Dactyloides.

A series of experiments were conducted to understand the seed dormancy breaking mechanism of buffalograss (Buchloe dactyloides). Buffalograss is a warm-season grass native to the Great Plains region of the United States, naturally occurring from Mexico to Canada. It is known for its low water use and fertility requirements compared to other turfgrasses commonly grown in the Great Plains such as Kentucky bluegrass (Poa pratensis) and tall fescue (Festuca arundinacea). It is a dioecious species; its pistillate plants produce burs that encapsulate 3-5 caryopses. The bur coat is one factor contributing to the strong seed dormancy response in buffalograss. The current accepted post-harvest treatment to break dormancy includes a 24 hour potassium nitrate (KNO3) treatment followed by a 4-6 week cold treatment. The mechanism of how the treatment breaks dormancy, which has been used since the 1940s, is still unknown. High seed costs are attributed in part to limited seed availability and the post-harvest treatment to break dormancy driving the importance to understand the buffalograss seed dormancy mechanisms. Various seed treatments including water soaking, detergents, gibberellic acid (GA), wetting agent, ammonium nitrate, among other treatments were studied but have yet to yield germination results equivalent to KNO3 treated seeds. Initial hormone profiling experiments showed that KNO3 treatments were increasing seed GA levels; however, subsequent studies from our lab did not yield consistent results. These results suggest KNO3 is not driving an increase in GA levels and instead may be affecting GA sensitivity or some other physiological mechanism breaking dormancy.