Effects of Osmopriming on Bermudagrass Germination and Establishment

Bermudagrass (Cynodon dactylon) is one of the most frequently-used turfgrasses for golf, sport, and recreational turf throughout tropical, subtropical, and transition zone regions of the world. Recently, a number of seeded bermudagrass cultivars have been released into the turfgrass market and are quickly becoming a popular option for turfgrass managers. A major limitation with these seeded bermudagrasses is poor or slow germination. This can lead to weed-infestation, which can ultimately result in a weak turfgrass stand. One possible means to overcome slow germination is the use of a pre-germination treatment such as osmopriming. The following study was designed to investigate the effects of two osmotic priming agents, polyethylene glycol (PEG) and potassium nitrate (KNO3) on the germination and establishment of a seeded bermudagrass. The cultivar, Jackpot, was exposed to seven different osmotic potential treatments within each solution, ranging from -0.20 to -0.5 MPa. Establishment after a 48 h exposure to these treatments was monitored for 6 weeks. Throughout the experiment, no conclusive evidence was obtained that priming of bermudagrass seed with varying osmotic solutions of PEG (avg. mol. wt. 10000) or KNO3 was an effective means to promote faster germination and establishment. No statistical difference could be detected between KNO3 and PEG and KNO3 actually provided inferior results to the control. Further research is needed to determine if other priming methods would be more effective to enhance bermudagrass germination. Bermudagrass (Cynodon dactylon L. Pers.) is a widely used turf and forage grass in the southern United States. While the majority of bermudagrasses are propagated by sod, plugs, or sprigging, recently developed seeded cultivars may be used for seeding or over-seeding lawns, golf courses and other turf areas. Seeding might be a more cost effective method of establishing new or over-seeded areas because plant material costs would be lower and easily available equipment could be used. To enhance the seeding process, methods to speed the germination and emergence of seed would be beneficial. Osmopriming is a well-established practice used to enhance germination of field and row crops, but relativity few studies have applied this technique to turfgrasses. Mauromicale and Cavallaro (1996) demonstrated that osmotic solutions of KNO3 and polyethylene glycol (PEG) enhanced the germination of a cool-season grass, tall fescue (Festuca arundinacea Schreb) and a warm-season grass, crabgrass (Dactylis glomerata L.). In addition, research on bahiagrass (Paspalum notatum Flügge) indicated a positive germination response to priming using PEG (Gates and Mullahey, 1997). Bush et al. (2000), working on the warmseason grasses, carpetgrass (Axanopus affinis Chase) and centipedegrass [Eremochloa ophiuroides Munro. (Kanz)], found that priming seed with KNO3 had a very positive effect on days to germination and percentage germination in both of these species. Collectively, these studies suggest that priming may have applications with bermudagrass to enhance the germination and establishment of seeded cultivars. Little specific work has been conducted on priming bermudagrass seed. In one study, Young et al. (1976) observed enhanced germination of common bermudagrass using solutions of KNO3, as well as solutions containing KNO3 and the plant growth regulator kinetin. In a study using ‘Guymon’ bermudagrass, hulled and unhulled seed were exposed to solutions of PEG (avg mol. wt. 8,000) and K3PO4. Hulled seed responded more favorably to the PEG solution while the un-hulled responded more to potassium phosphate (K3PO4) (Brede and Brede, 1986). In another study in which common bermudagrass seed was planted through a hydro-seeder (Kay et al., 1977), solutions of a kinitin, gibberellin (GA3) and potassium nitrate (KNO3) were used to osmoprime the seed. This study found that soaking seeds for 24 h in a combination of kinitin, gibberellin (GA3) and potassium nitrate (KNO3) yielded the most effective results. Osmopriming and/or pre-germination of bermudagrass seed may allow for faster establishment, which will enhance the use of seeded bermudagrass cultivars. Unfortunately, there has been no research on many of the newer seeded bermudagrass cultivars. As such, the objective of this study was to determine if osmotic priming is an effective means to enhance the germination and establishment of bermudagrass.