2,310 research outputs found
You Donât Have To Go Home But You Carrot Stay Here: Root-Knot Nematode Biological Control in Carrots
Root-knot nematodes cause tens of billions of dollars in damages annually in agricultural production. The enormous economic losses brought about by nematodes, combined with the downsides to current methods for handling them, have led to an increased focus in understanding natural plant defense mechanisms and finding alternative methods to lessen the damage done by root-knot nematodes. Endophyte biocontrol agents such as Trichoderma harzianum have shown promise in reducing nematode damage. Recent studies have demonstrated that soil management practices and plant genotype can influence endophyte community structure, but it is unclear whether such differences influence susceptibility to nematode damage. This study seeks to better understand these dynamics by quantifying how differences in endophyte community structure influence nematode (Meloidgyne incognita) infection and plant performance in three carrot varieties that are susceptible, moderately resistant, or highly resistant to nematodes. The treatments are 1) unamended control, 2) Trichoderma harzianum, 3) endophytes from an organically farmed field, and 4) endophytes from a conventionally farmed field. Preliminary results indicate that carrot genotype significantly impacts carrot biomass, and carrots grown in the presence of endophytes from organically farmed soils have greater biomass than carrots grown in the other treatments. Analysis of endophyte community structure and nematode infection are ongoing
The 2016 Stormwater Bill: An Analysis of Perceived and Real Problems with Proposed Solutions
Effects of bromide and iodide on stalk secretion in the biofouling diatom Achnanthes longipes (Bacillariophyceae)
Extracellular polymeric substance (EPS) secretion was examined in the stalked marine diatom Achnanthes longipes Ag. in defined medium. This common biofouling diatom exhibited an absolute requirement for bromide for stalk production and substratum attachment, whereas elevated iodide concentrations in the growth medium inhibited stalk formation and adhesion. Varying EPS morphologtes resulted from altering bromide and iodide levels: pads, stalkâpads, stalks, and no EPS. Cells showed no differences in growth with bromide or iodide concentrations, indicating that they were not physiologically stressed under conditions that impaired EPS secretion. Cells grown in elevated iodide secreted significantly more soluble extracellular carbohydrate into the medium, suggesting that the EPS was soluble and unable to be polymerized into a morphologically distinct gel. By replacing sulfate with methionine, the diatom lost its ability to form stalks even in the presence of bromide, indicating that free sulphate may be required for proper crossâlinking of stalk polymers. LotusâFITC, a fluorescentâtagged lectin, preferentially labeled the EPS and, thus, was used to visualize and quantify EPS secretion along a bromide gradient in conjunction with an image analysis system. This technique demonstrated a direct correlation between the amount of bromide present in the medium and the specific EPS morphology formed. Copyright © 1995, Wiley Blackwell. All rights reserve
Mechanisms of Surviving Burial: Dune Grass Interspecific Differences Drive Resource Allocation After Sand Deposition
Sand dunes are important geomorphic formations of coastal ecosystems that are critical in protecting human populations that live in coastal areas. Dune formation is driven by ecomorphodynamic interactions between vegetation and sediment deposition. While there has been extensive research on responses of dune grasses to sand burial, there is a knowledge gap in understanding mechanisms of acclimation between similar, coexistent, dune-building grasses such as Ammophila breviligulata (C3), Spartina patens (C4), and Uniola paniculata (C4). Our goal was to determine how physiological mechanisms of acclimation to sand burial vary between species. We hypothesize that (1) in the presence of burial, resource allocation will be predicated on photosynthetic pathway and that we will be able to characterize the C3 species as a root allocator and the C4 species as leaf allocators. We also hypothesize that (2) despite similarities between these species in habitat, growth form, and life history, leaf, root, and whole plant traits will vary between species when burial is not present. Furthermore, when burial is present, the existing variability in physiological strategy will drive species-specific mechanisms of survival. In a greenhouse experiment, we exposed three dune grass species to different burial treatments: 0 cm (control) and a one-time 25-cm burial to mimic sediment deposition during a storm. At the conclusion of our study, we collected a suite of physiological and morphological functional traits. Results showed that Ammophila decreased allocation to aboveground biomass to maintain root biomass, preserving photosynthesis by allocating nitrogen (N) into light-exposed leaves. Conversely, Uniola and Spartina decreased allocation to belowground production to increase elongation and maintain aboveground biomass. Interestingly, we found that species were functionally distinct when burial was absent; however, all species became more similar when treated with burial. In the presence of burial, species utilized functional traits of rapid growth strategy, although mechanisms of change were interspecifically variable
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