Competition is assessed in these studies under varied levels of P fertilizer amendment of muck soil. Glauninger and Holzner discussed why competition for nutrients is not estimable by simply looking at nutrient levels in plants. Deionized water was applied to the surface as needed in order to keep the vermiculite moist until seedling emergence was complete. These studies showed that equivalent yields can be obtained with two thirds lower fertilizer P rates if the nutrient is applied in a band rather than broadcast. This can be attributed to the late time of establishment of the amaranth relative to the crop in the fall of Table 3. In this experiment, the emergence of spiny amaranth relative to that of the crop occurred later than in the spring experiment. In these studies, competition is found to be dependent on amounts of nutrients supplied to plants grown in mixture.

Per plant dry weight data were analyzed using analysis of variance with a complete factorial treatment arrangement. Phosphorus is applied based on quantitative analysis of soil for water extractable P. As P concentration in lettuce tissue increased from 0. Since little detailed information on the effect of weeds on lettuce is available, studies were designed to assess both the effect of weed density and duration of weed presence on the crop under several fertilizer P application regimes. The studies were conducted in air- conditioned glasshouses, the first during August and September of at Gainesville, Florida, the second in March of spring at Belle Glade, Florida and the third in September of fall at Belle Glade. In situations where water and nutrients are adequate, light is the factor that will ultimately determine plant growth Gardner et al.

Seeding dates are given in Table 3.

Nitrogen concentrations ranged from 1. These differences occurred regardless of whether one half or one third of amzranthus broadcast rate was used ob the band application and, therefore, may be due to more than optimization of rate. Phosphorus concentrations in the fall study were influenced by duration of weed interference but not the other experimental factors Table 3. In the spring experiments lettuce yields were reduced most when spiny amaranth was present at high densities throughout the season until the time of harvest of the crop.


Prior to analysis, amaranth data were log transformed after adding 1 to the data values. They found that competitive interference occurred for P with common lambsquarters reivew more aggressiveand to a lesser extent for N in which case wheat was more aggressive.

Literature review on amaranthus hybridus – Don’t have time to do homework

Daniel Colvin for their guidance and support during the course of my studies at the University of Florida. These increases may be the result of reduced plant growth due to others factors becoming limiting rather than an increase in nutrient uptake.

literature review on amaranthus hybridus

This was demonstrated in greenhouse experiments where P was applied simultaneously by 2 methods Costigan, Spiny amaranth plants removed from plots were dried at 60 C. The overall objective of studies reported here was to assess the competitive interactions under varied P regimes between lettuce and spiny rsview Amaranthus spinosus L.

With the earliest barley planting, the crop progressively suppressed the weed.

Timber Press, Portland, OR. A pressed bed planting system was used Lucas, During the final five weeks prior to harvest of the spring experiment there was considerable rainfall and substantially reduced solar radiation during two periods regiew several days.

literature review on amaranthus hybridus

With more closely spaced rows the canopy would close earlier. As P concentration in lettuce tissue increased from 0.

Literature review on amaranthus hybridus

It is not clear why yields were reduced by the low weed density in the spring of but not in Preliminaries 2 and 3 were limited to a single density Table 4. These results suggest that further study of fertilizer P placement is needed. Phosphorus application was found to affect amaranth biomass only in the case of the final DWI. There did not appear to be any meaningful trends for Ca concentration response to P application.


Some information concerning the effect weeds have on lettuce is found in studies in which herbicides and other control methods are evaluated Dusky et al. The influence of one nutrient on competition may also be dependent on the status of other hybirdus.

The hgbridus greater yield reduction in than may be related to the manner in which yield reductions occurred. Spiny Amaranth Nutrient Analysis Macronutrient concentrations in spiny amaranth for the springfall and spring experiments are given in Tables 3. Spiny amaranth biomass, on the other literatue, was only marginally influenced by P fertilization. Phosphorus Duration of weed interference Amarathus 6 16 27 35 biomass g plant’ – None 1.

While lettuce growth was dependent on P fertilization, this was not found to be the case for spiny amaranth. Durations of weed interference, in days after plot establishment, are 7, 21, 35 and 497, 17, 28 and 36 and 6, 16, 27 and 36 for experiments 1, 2 and 3, respectively.

For gramineous weeds, postemergence herbicides are available Stall and Dusky, Duration of interference reduced lettuce yields in a quadratic fashion with broadcast P application in spring and As a means of assessing the relative importance of plant competition due to below-ground interactions versus those occurring above-ground, Wilson summarized the results of a number of studies found in the literature in which separation of root and shoot competition was attempted.

Low and high densities are 1 and 4 plants per 2. It appears that the influence of nutrient addition on plant competition must be considered on a case by case basis rather than broad generalization.