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Monday, July 27, 2020 | History

2 edition of effect of a nitrogen on competitive interactions in a weed-crop community. found in the catalog.

effect of a nitrogen on competitive interactions in a weed-crop community.

Jennifer M. Smith

effect of a nitrogen on competitive interactions in a weed-crop community.

by Jennifer M. Smith

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  • 39 Currently reading

Published by University of East Anglia in Norwich .
Written in English


Edition Notes

Thesis (Ph.D.), University of East Anglia, School of Biological Sciences, 1993.

ID Numbers
Open LibraryOL20717096M

  The absence of any interactions among the three factors in influencing the weed fraction of the total biomass is noteworthy because effects of nitrogen addition on crop vs. weed growth will be influenced by the relative size of crop and weeds and their relative abilities to take up nitrogen under low and high soil nitrogen levels.   The different slopes of the two regressions in Fig. 3a further suggest that nitrogen deposition has a stronger negative effect at highly productive sites, where nitrogen .

The ability to invade communities in a variety of habitats (e.g., along a depth gradient) may facilitate establishment and spread of invasive plants, but how multiple lineages of a species perform under varying conditions is understudied. A series of greenhouse common garden experiments were conducted in which six diploid and four triploid populations of the aquatic invasive plant Butomus. Weeds can cooperate with the agroecosystem’s functioning by providing ecosystem services. Effective weed management should mitigate negative weed–crop interference, while maintaining a functional and balanced weed community. In a two-year trial, the in-line/roller crimper (RC) was used to terminate an agroecological service crop (ASC; here barley, Hordeum vulgare L.) before organic.

Field experiments were conducted in farmers’ rice fields in and to study the effects of nitrogen (N) management strategies on N use efficiency in recovery (RE), agronomy (AE) and physiology (PE) and redistribution of dry matter accumulation (DMA) and nitrogen accumulation (NA) in two typical rice cultivars in Jinhua, Zhejiang Province. Human activity in the last century has increased nitrogen (N) deposition to a level that has caused or is likely to cause alterations to the structure and function of many ecosystems across the United States. We synthesized current research relating atmospheric N deposition to effects on terrestrial and freshwater ecosystems in the United States, and estimated associated empirical critical.


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Effect of a nitrogen on competitive interactions in a weed-crop community by Jennifer M. Smith Download PDF EPUB FB2

Weeds impact crop yields primarily by competing for limited resources such as sunlight, water and nutrients. Numerous studies have investigated how changing nutrient availability via fertilization influences the competitive relationship. In some situations fertilization favors crop growth over weeds, and therefore reduces yield loss, whereas in others weed growth is benefited more than crop.

The intensification of agricultural activities has provided unprecedented increases in crop production. In the light of this development concerns have been raised about its negative environmental impact.

High-input farm management has further reduced the weed diversity and shaped weed communities to consist of a few highly competitive weed : Lukas Hallberg. Results from this study indicate that the effects of N fertilization on early-season crop growth provided a competitive advantage for corn relative to weeds, thereby increasing the length of time.

PDF | Plants alter soil biota which subsequently modifies plant growth, plant–plant interactions and plant community dynamics. While much research has | Find, read and cite all the research. weed /crop interfer ences has been wild oat was better able to utilize the added nitrogen and thus gained a competitive advantage over the wheat.

The effects on weed community composition. Abstract Information on nitrogen fertilizer effects on crop-weed competitive interactions might aid in developing improved weed management programs. Information on nitrogen fertilizer effects on crop–weed competitive interactions might aid in developing improved weed management programs.

A controlled environment study was conducted to examine the effect of three N rates on the competitive ability of four weed species grown with wheat. The four weed species were chosen to represent species that varied in their growth responsiveness to.

A field study at the Agricultural University of Timiriazev, Moscow, was conducted to determine the effect of crop rotation and Long-term fertilizer application on differences in the competitive ability of spring barley and weeds to nutrient uptake in and Nitrogen management practices can affect the outcome of competition with respect to the weed population and its competitive ability relative to the crop (Evans et al., ; Wortman et al., ).

It has been reported that broadcast nitrogen application stimulates the growth of Bromus tectorum L. more than does deep band placement in a fallow wheat system (Ball et al., ). weed crop competition. Weeds usually absorb mineral nutrients faster than many of our crop plants and accumulate them in their tissue in relatively large amounts.

Fig. Effect of nitrogen addition and two weeds (barnyardgrass and the annual broadleaf Monchorias) on rice yield (redrawn from data from Moody, in Zimdahl, ).

Siderophores are related to competitive and cooperative microbial interactions and can also play other roles, such as signaling and antibiotic activity. 62 Hopanoids play an important role in bacterial interaction, conferring tolerance and improving the adaptation of bacteria in different environments, 64, 65 In fungi, the compounds.

Indirect effects may occur by altering the overall size asymmetry of competition through root–shoot competitive interactions. Methods We used a phytometer approach to examine the effects of root, shoot and total competition intensity and importance on evenness of experimental plant communities.

Also, much of this work is based on perennial systems. While competitive relationships within a single growing season may influence longer term trends in crop–weed interactions, often changes that occur over the short term in a plant community may be quite different to.

fertilization. Figure 4 shows this relationship in the competitive interaction of barnyardgrass in rice. At low nitrogen rates increasing weed densities produce a modest decline in yield.

However, at the highest nitrogen level barnyardgrass caused very steep declines in rice yields. The effect of fertilizer nitrogen on weed-crop competition is largely dependent on fertilizer placement.

Generally, in studies where weed growth has been favoured over crop growth, the nitrogen has been broadcast. Banding nitrogen close to the seedrow allows the crop roots to use applied fertilizer more efficiently than weeds.

The effect of nitrogen on competitive interactions in a weed-crop community. Author: Smith, Jennifer M. ISNI: Awarding Body: University of East Anglia Current Institution: University of East Anglia Date of Award: Availability of Full Text.

Nitrogen enrichment can structure marsh communities by mediating both plant competitive and facilitative interactions and plant-herbivore interactions. For example, Levine et al. () showed that nutrients mediate Iva frutescens and J. gerardi competitive and. Weeds, which had high dry matter production at high N application rates in monoculture, were most competitive at low N and least sensitive to low applied N.

Nitrogen application levels sub-optimal to rice reduced the competitive ability of rice when in mixture with E. indica, R. cochinchinensis, and A spinosus, but not with C.

rotundus. As common ragweed (Ambrosia artemisiifolia L.) spreads across Europe and other regions, it is becoming both a health and an economic threat. To better understand which environmental conditions facilitate the spread of the invasive species, ina greenhouse experiment was conducted determining the effects of various nitrogen levels (10, 50 and kg N/ha), soil moisture level (low.

Organic manure may affect crop-weed competitive interactions differently than chemical nitrogen fertilizer (Davis and Liebman, ), probably due to speed of N release or form of N. In a study. Nitrogen is one of the most important nutrients which can change competition ability of weeds and crops.

Nitrogen increased the growth and production of wheat through increasing leaf area and photosynthetic efficiency of leaves; moreover, it has effects on increasing spike number in .Effect of nitrogen fertilizer and landscape position on wild oat (Avena fatua) interference in spring wheat - Volume 53 Issue 6 - Delaney M.

Ross, Rene C. Van Acker but preseed spring broadcast nitrogen fertilizer does make wild oat more competitive in spring wheat. Soil variables and interactions affecting prediction of crop yield pattern.Effects of nitrogen supply on competition between wheat and three annual weed species.

J. IQBAL. School of Agricultural and Forest Sciences. University of Wales, Bangor. Gwynedd. LL57 2UW. UK. Search for more papers by this author. D. WRIGHT. School of Agricultural and Forest Sciences.

University of Wales, Bangor.