Evidence of different compounds in smoke derived from legumes and grasses acting on seed germination and seedling emergence

Our previous study showed that smoke derived from alfalfa (Medicago sativa) caused different germination responses compared with that from prairie hay (Festuca hallii) and wheat straw (Triticum aestivum), but the mechanism remained unclear. In this study, we used Salad Bowl lettuce (Lactuca sativa) as a quick bioassay to trace the active compounds in each of these three smoke solutions. Column chromatography and high performance liquid chromatography (HPLC) were used to separate and identify active fractions. Seeds of four species from Fescue Prairie were primed for 24 h at room temperature in darkness using serial dilutions of separated active fractions, as well as karrikinolide (KAR1). After priming, seeds were dried at room temperature in darkness for 7 days and subsequently incubated at 10/0°C or 25/15°C in 12 h light–12 h dark or 24 h darkness for 49 days. KAR1was in the smoke made from prairie hay, and wheat straw, but was absent in alfalfa smoke. Priming in KAR1solutions increased germination of three native species. Priming in highly concentrated KAR1reduced radicle length ofCirsium arvense, the only non-native species. Even though KAR1has the potential to enhance regeneration of native species in the Fescue Prairie, KAR1is not universally present in smoke derived from different plant materials. Unknown compound(s) in smoke derived from legumes remain to be identified.

Smoke originating from different plants has various effects on germination and seedling growth of species in Fescue Prairie

Little is known about how smoke, an important germination cue, influences seed regeneration of species in Fescue Prairies. Whether germination and seedling growth responses vary with smoke produced from different materials is still ambiguous. In this study, seeds of four forbs from a Fescue Prairie were primed in serial dilutions of aqueous smoke solutions produced from alfalfa (Medicago sativa L.), prairie hay (Festuca hallii (Vasey) Piper), and wheat straw (Triticum aestivum L.), and incubated at 10–0 °C or 25–15 °C in a 12 h light – 12 h dark cycle or 24 h darkness for 49 d. Nonprimed seeds and those primed in distilled water were used as controls. Germination and radical length of Conyza canadensis (L.) Cronquist increased after priming in concentrated smoke-solutions derived from alfalfa, but decreased after priming in the same concentrated smoke solutions made from prairie hay and wheat straw at 25–15 °C in 24 h darkness. Smoke substituted for light improved germination of Artemisia ludoviciana Nutt. Our results indicate that the effect of smoke on seed germination and seedling growth was temperature- and light-dependent. It appears that smoke produced from alfalfa had different compounds that, in turn, had different germination and seedling growth responses as compared with the smoke produced from prairie hay and wheat straw.

Does Festuca hallii (Vasey) Piper produce and display more leaves on tillers after defoliation?

Romo, J. T. 2013. Does Festuca hallii (Vasey) Piper produce and display more leaves on tillers after defoliation? Can. J. Plant Sci. 93: 161–164. Leaves per tiller produced and displayed following June, July, or August defoliation was determined for Festuca hallii. Two to three leaves per tiller were produced and displayed annually, and leaves per tiller did not vary among defoliation treatments. June defoliation reduced green leaves per tiller; leaf senescence increased after June and July defoliation.

Above-ground net primary production of plains rough fescue [Festuca hallii (Vasey) Piper] after a single defoliation on five landform elements

Pantel, A., Romo, J. T. and Bai, Y. 2011. Above-ground net primary production of plains rough fescue [ Festuca hallii (Vasey) Piper] after a single defoliation on five landform elements. Can. J. Plant Sci. 91: 689–696. Above-ground net primary production (ANPP) was determined for plains rough fescue [Festuca hallii (Vasey) Piper] following a single defoliation to 7.5 cm stubble height on five landform elements in the Northern Mixed Prairie. The landform elements included north aspect-concave slopes, north aspect-convex slopes, south aspect-concave slopes, south aspect-convex slopes, and level uplands. Above-ground net primary production was determined for 2 yr after defoliating plants in May through November. Above-ground net primary production after defoliation was not dependent on landform elements in the first (P=0.23) and second years (P=0.22) after defoliation. In the first year after June through September defoliation, ANPP was reduced 29 to 41% (P <0.01), whereas May, October, or November defoliation had no significant effect on ANPP. Above-ground net primary production did not vary significantly (P=0.61) among months of defoliation in the second year after defoliation. Less ANPP in the first year after June through September defoliation indicates the need for ≥1 yr of deferred use to allow plants to regain their production potential. Unaffected ANPP after May, October, or November defoliation suggests plains rough fescue can be grazed annually. Recuperation of ANPP after defoliation depends on the month of the year in which plains rough fescue is defoliated, but not on landform elements in the Northern Mixed Prairie.

Patterns of amplified restriction fragment polymorphism in the germination of Festuca hallii seeds

Timing of seed germination influences plant lifetime fitness and can affect the ability of plant populations to colonize and persist in changing environments. However, the genetic variation of the seed germination response remains poorly understood. The amplified restriction fragment polymorphism (AFLP) technique was applied to characterize the genetic variation of germinated seeds collected from three Festuca hallii populations in the Canadian prairie. Three subpopulations with early, intermediate and late germination were identified from each population, based on germination tests at 10, 15 and 20°C in controlled growth chambers. Three AFLP primer pairs were employed to screen a total of 540 assayed seedling samples and 188 polymorphic AFLP bands were scored for each sample. None of the assayed AFLP bands were significantly associated with seed germination, but marked differences in estimates of mean band frequency were observed for various groups of germinating seeds under different test temperatures. Partitioning of the total AFLP variation showed that 5.9% AFLP variation was present among seeds of the three populations, 0.3% among seeds of three germination subpopulations, and 0.5% among seeds grouped for germination temperature. Genetic differentiation was significant among 27 groups of seeds representing population, germination timing and test temperature. Subpopulations with early and intermediate germination shared similar genetic backgrounds and were genetically differentiated from the late germination subpopulation. These results indicate that seed genotypes respond slightly differently to environmental variation, resulting in significant but weak genetic differentiation in the germination of F. hallii seeds. Implications for plant establishment and fescue restoration are discussed.