Browsing by Subject "seedling emergence"

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    Effects of soil warming history on the performances of congeneric temperate and boreal herbaceous plant species and their associations with soil biota
    (2016) Thakur, Madhav P; Reich, Peter B; Wagg, Cameron; Fisichelli, Nicholas A; Ciobanu, Marcel; Hobbie, Sarah E; Rich, Roy L; Stefanski, Artur; Eisenhauer, Nico
    Aims Climate warming raises the probability of range expansions of warm-adapted temperate species into areas currently dominated by cold-adapted boreal species. Warming-induced plant range expansions could partly depend on how warming modifies relationships with soil biota that promote plant growth, such as by mineralizing nutrients. Here, we grew two pairs of congeneric herbaceous plants species together in soil with a 5-year warming history (ambient, +1.7°C, +3.4°C) and related their performances to plant-beneficial soil biota. Methods Each plant pair belonged to either the mid-latitude temperate climate or the higher latitude southern boreal climate. Warmed soils were extracted from a chamberless heating experiment at two field sites in the temperate-boreal ecotone of North America. To isolate potential effects of different soil warming histories, air temperature for the greenhouse experiment was identical across soils. We hypothesized that soil with a 5-year warming history in the field would enhance the performance of temperate plant species more than boreal plant species and expected improved plant performances to have positive associations with plant growth-promoting soil biota (microbial-feeding nematodes and arbuscular mycorrhizal fungi). Important Findings Our main hypothesis was partly confirmed as only one temperate species performed better in soil with warming history than in soil with history of ambient temperature. Further, this effect was restricted to the site with higher soil water content in the growing season of the sampling year (prior to soil collection). One of the boreal species performed consistently worse in previously warmed soil, whereas the other species showed neutral responses to soil warming history. We found a positive correlation between the density of microbial-feeding nematodes and the performance of one of the temperate species in previously wetter soils, but this correlation was negative at the site with previously drier soil. We found no significant correlations between the performance of the other temperate species as well as the two boreal species and any of the studied soil biota. Our results indicate that soil warming can modify the relation between certain plant species and microbial-feeding nematodes in given soil edaphic conditions, which might be important for plant performance in the temperate-boreal ecotone.
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    Giant Ragweed (Ambrosia trifida) Seed Bank Dynamics and Management
    (2015-07) Goplen, Jared
    As herbicide-resistant weed populations become increasingly problematic in crop production, alternative strategies of weed control are necessary. Ambrosia trifida, one of the most competitive agricultural weeds in row crops, has developed resistance to multiple herbicide biochemical sites of action within the plant, necessitating the development of new and integrated methods of weed control. This research indicates that various crop rotations are more conducive to giant ragweed emergence than others, and that long term giant ragweed management can be accomplished by implementing a zero weed threshold to deplete the weed seed bank. Giant ragweed also retains seed well into the harvest season, indicating that there is ample time to remove escaped giant ragweed from production fields prior to seed shattering to limit replenishment of the weed seed bank. Ultimately, these results indicate that there is potential to manage Ambrosia trifida by eliminating seed bank inputs and degrading the weed seed bank.
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    Raw data for Xyloglucan deficiency leads to a reduction in turgor pressure and changes in cell wall properties affecting early seedling establishment
    (2024-04-08) Bou Daher, Firas; Serra, Leo; Carter, Ross; Jönsson, Henrik; Robinson, Sarah; Meyerowitz, Elliot M; Gray, William M; grayx051@umn.edu; Gray, William M; William Gray Lab
    Xyloglucan is believed to play a significant role in cell wall mechanics of dicot plants. Surprisingly, Arabidopsis plants defective in xyloglucan biosynthesis exhibit nearly normal growth and development. We investigated a mutant line, cslc-Δ5, lacking activity in all five Arabidopsis CSLC genes responsible for xyloglucan backbone biosynthesis. We observed that this xyloglucandeficient line exhibited reduced cellulose crystallinity and increased pectin levels, suggesting the existence of feedback mechanisms that regulate wall composition to compensate for the absence of xyloglucan. These alterations in cell wall composition in the xyloglucan-absent plants were further linked to a decrease in cell wall elasticity and rupture stress, as observed through atomic force microscopy and extensometer-based techniques. This raised questions about how plants with such modified cell wall properties can maintain normal growth. Our investigation revealed two key factors contributing to this phenomenon. Firstly, measurements of turgor pressure, a primary driver of plant growth, revealed that cslc-Δ5 plants have reduced turgor, preventing the compromised walls from bursting while still allowing growth to occur. Secondly, we discovered the conservation of elastic asymmetry (ratio of axial to transverse wall elasticity) in the mutant, suggesting an additional mechanism contributing to the maintenance of normal growth. This novel feedback mechanism between cell wall composition and mechanical properties, coupled with turgor pressure regulation, plays a central role in the control of plant growth and is critical for seedling establishment in a mechanically challenging environment by affecting shoot emergence and root penetration.