Identification and Quantification of Abscisic Acid in Zoysiagrass Seeds and Its Inhibitory Effect on Germination
- Do Yi Yeam,
- N. Bhushan Mandava,
- Paul H. Terry,
- J. Jack Murray and
- H. L. Portz
- D ep. of Horticultural Science, Seoul Natl. Univ., Suweon, Korea;
T odhunter, Mandava and Assoc., 1625 K St., Suite 975, Washington, DC 20036;
P lant Hormone Lab. Beltsville Agric. Res. Ctr., Beltsville, MD 20705
P lant Germplasm Quality and Enhancement Lab., Beltsville Agric. Res. Ctr., Beltsville, MD 20705;
D ep. of Plant and Soil Science, Southern Illinois Univ., Carbondale, IL 62958.
Seed dormancy has been a major limiting factor in the use of zoysiagrass (Zoysia japonica Steud.) for turf. The identification of the major dormancy factors and their mode of action would increase the potential for developing seed treatments to break dormancy. Abscisic acid (ABA), a well-known seed dormancy-inducing substance found in the dormant seeds of many temperate perennial weeds and grasses, was confirmed and quantified in Zoysiagrass seed. High performance liquid chromatography was used to purify the seed extract, gas chromatography/electron capture was used to quantitate the amount of ABA present in the seeds via the methyl ester, and further verification of the compound in the seed as ABA was made using masspectrometry. The quantity of the cis, trans isomer found, 3.44 mg ABA kg1 seed, is the highest level of ABA reported for any seed. There was no trans, trans isomer found in zoysiagrass seed. The high level of ABA may be the reason that dormancy is so difficult to break in zoysiagrass seed. Exogenous ABA applied to nondormant (KOH and light treated) seed inhibited germination. Germination after 21 d was reduced 69 and 95% by 0.4 and 40.0 μM of ABA, respectively. The promotive effects of light on germination were reversed by ABA applications. A positive relationship was found between ABA concentration and the duration of light required for germination.
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