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Wild Mustard Seed's "Suicidal Germination" after Smoke water priming: A promising tool for weed management




Godakanda, Asanka Ravinatha
Bai, Yuguang
Reaney, Martin
Shen, Jianheng
Wang, Ruojing

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Fire is a natural disturbance which plays a key role in maintaining ecosystem functioning of Fescue Prairies. Smoke produced during the burning of plant material have shown promotive action on seed germination in plant species including arable weeds and crops in both fire-prone habitats and fire-free habitats around the World. To date, few beneficial chemicals have been characterized from plant-derived smoke water solutions such as Karrikin (KAR1), Cyanohydrin, Hydroquinine etc. These isolated chemicals have demonstrated a positive effect in breaking seed dormancy followed by stimulated seed germination and seedling growth in species and growth condition specific manner. Seed related smoke-induced physiological mechanisms includes activation of enzymes, phytochrome-mediated, other phytohormone interaction and improved rate of germination and seedling vigour. Recent study showed that alfalfa-derived smoke does not contain KAR1. But it showed a promotive and a light requirement substitution action on germination of selected fire responsive fescue prairie forbs, indicating that a different chemical compound is active in alfalfa-derived smoke. The present study was conducted to investigate (1) light-substitution ability of different smoke; (2) the wild mustard seed priming effect with alfalfa smoke water; and (3) the efficacy of using non-polar resin in fractionating active compounds in alfalfa smoke water. In experiments smoke-responsive wild mustard (Sinapis arvensis L.) and lettuce (Lactuca sativa L. cv. Salad Bowl) seeds were used during dark germination as rapid bioassay species under laboratory conditions. Smoke water solutions were produced by smoldering alfalfa hay and six savannah fire ephemerals. Alfalfa smoke water serial dilutions (1/1000v/v, 1/100v/v, 1/10v/v and 1/1v/v) and HPLC grade distilled water (control) were used as the seed priming treatments in further experiments. Lettuce seed plates were incubated in 24 h fully darkness at alternate 25/15°C for 01 day. Wild mustard seeds were primed for 24 h in darkness followed by 7 d drying at 20°C in darkness before adding distilled water. Seeds were incubated at constant 20°C under 16 h light/8 h darkness or 24 h darkness for 10 days. A non-polar resin (FPX-66) was used to isolate the active chemical compound in alfalfa smoke water. Three fractions were tested with Lettuce bioassay and 1D 1H NMR spectra analysis. At 25/15°C, Salad bowl bioassay significantly (P<0.001) responses to smoke water solutions irrespective of the smoke types except Eragrostis curvula and Hilliardiella spp. Dilutions, 1/1 v/v and 1/10 v/v have a negative effect on lettuce seed dark germination. In wild mustard seeds, except 1/100 v/v dilution, all other alfalfa smoke water dilutions have maintained a significant seed germination capacity (P<0.001) and pattern over the time showing a suicidal dark germination. Resin fractions significantly (P<0.05) increase lettuce seed dark germination compared to control. 1D 1H NMR spectra for 100% aqueous fraction showed a proton pattern closer to the standard KAR1, indicating the efficacy of non-polar resin in isolating active compounds. Thus, it can be concluded that higher smoke responsiveness of wild mustard seeds is an economically important



alfalfa smoke, seed priming, lettuce and wild mustard seed, resin, NMR








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Soils and Crops Workshop