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ARS Home » Plains Area » Lincoln, Nebraska » Wheat, Sorghum and Forage Research » Research » Publications at this Location » Publication #330388
Title: Potassium nitrate alters buffalograss bur permeability

Author
item KREUSER, KATHERINE - University Of Nebraska
item KREUSER, WILLIAM - University Of Nebraska
item Sarath, Gautam
item AMUNDSEN, KEENAN - University Of Nebraska

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2016
Publication Date: 12/1/2016
Publication URL: https://handle.nal.usda.gov/10113/5763051
Citation: Kreuser, K., Kreuser, W., Sarath, G., Amundsen, K. 2016. Potassium nitrate alters buffalograss bur permeability. HortScience. 51(12):1566-1572. doi:10.21273/HORTSCI11126-16.

Interpretive Summary: Buffalograss is a native turf species widely used across different landscapes. However, the plant suffers from low germination, largely as a result of seed dormancy. Buffalograss seeds, called burs, contain 3 or more germinable caryopses. The physiological mechanisms that impose seed dormancy or those that enhance germination in intact burs are not known for this species. Seed producers often use a priming method of soaking burs in a dilute solution of potassium nitrate to enhance germination rates. Although moderately effective for some seed lots, this priming technique adds an economic burden for producers. In this study the efficacy of different priming treatments (water vs potassium nitrate) were used to quantify changes in seed hormones normally associated with promoting germination or imposing dormancy. Additional tests were performed to understand how priming affected water uptake by treated or untreated burs. Results on plant hormone analyses were inconclusive, but indicated that potassium nitrate treatment improved water uptake by the burs, which could be one component for improved germination in seed lots primed with this chemical.

Technical Abstract: Buffalograss is a warm-season, dioecious grass species yielding burs, which are routinely used for field plantings. The pistillate plants bear the burs containing 1–5 caryopses. Isolated caryopses readily germinate, but caryopses contained within burs exhibit strong dormancy, suggesting that burs inhibit germination. Priming burs with low concentrations of potassium nitrate (KNO3) is used as an industry standard to improve germination. Seed dormancy and germination in many species are strongly influenced by endogenous hormone levels, principally abscisic acid (ABA) and gibberellic acid (GA). It follows that buffalograss seed dormancy might be induced or overcome by altering the ratio of ABA to GA. The objectives of this research were 1) to contrast the effects of priming with KNO3 or water on bur germination, 2) to study how these treatments affected hormone profiles, specifically the ABA/GA ratios in the burs, and 3) to quantify treatment effects on the water permeability of the burs. Hormone profiles were analyzed following four postharvest seed-soaking treatments (24-hour 0.05 M KNO3, 24-hour H2O, 48-hour 0.05 M KNO3, and 48-hour H2O). Water infiltration tests on nontreated, 24-hour H2O-treated, and 24-hour 0.05 M KNO3-treated seeds were also conducted. Inconclusive hormone profiling results did not support the hypothesis that KNO3 postharvest treatment raises GA levels to encourage germination. Instead, our data support changes in seed morphology following KNO3 postharvest seed treatments which alter water permeability of the seedcoat leading to increased germination.