In order to address the question of the effect that density has on competitive relations, the method can be further expanded by conducting the replacement series at varied densities Jolliffe et al. Based on these findings, it was suggested that cloudy weather may be a limiting factor for lettuce yields in south Florida. A study by Chambers and Holm using P32 to study the site of P uptake from soil by green foxtail Setaria viridis L. Although the crop was affected by spiny amaranth interference, the immediate cause of yield loss to the weed does not appear to be due to interference with the P nutrition of the crop. This suggests that interference for light between plants may have been a factor involved in the biomass responses to density.
Analysis of the spring yield data suggested that slightly greater yields were obtained with the broadcast than the band application. The approach utilizes the replacement series method. Phosphorus applied broadcast as an experimental treatment. Literature review on amaranthus hybridus 19 feet 2 inch amaranth hybridus. For gramineous weeds, postemergence herbicides are available Stall and Dusky, In these studies with lettuce and spiny amaranth, however, essentially only the growth of lettuce was found to be influenced by P fertility.
Studies have been conducted to compare some of the alternative approaches to competition analysis literatuer applied to specific situations Rejmanek et al. Fertilizer P application resulted in higher spiny amaranth P concentrations, which were also greater with the broadcast than the band application.
Environmental concerns, among others, call for reduced fertilizer application due to its potential adverse effect on wetland ecosystems which are closely linked to agricultural lands. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. The projected yield is a hypothetical curve of how the yield of a monoculture would respond to plant density in the absence of intraspecific competition.
Spiny amaranth biomass, on the other hand, was only marginally influenced literatufe P fertilization. This is because plants differ in their capacity to use light in photosynthesis Gardner et al.
Lettuce yields were also influenced by fertilization such that application by either method resulted in yield increases of approximately percent. These were applied 1 to 3 times weekly.
When weeds were present until time of harvest of the crop, weed biomass under the banded P application was greater than where no P was added. General treatment of the topic often begins with a discussion of methodology Radosevich and Roush, ; Spitters and van den Berg, These factors were examined at several fertilizer P application options.
These extended to 30 cm above the pot surface. The replacement design is used for determining which of two components of a binary mixture is the better competitor. Spiny amaranth biomass data were analyzed using techniques similar to those used for lettuce.
Non- transformed means are presented.
Literature review on amaranthus hybridus
Prior to selecting the field location for each experiment, soil was sampled and analyzed for nutrients as described by Sanchez These differences occurred regardless of whether one half or one third of the broadcast rate was used in the band application and, therefore, may be due to more than optimization of rate.
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.
This transformation resulted in residual plots which appeared to be of random distribution. Email required Address never made public. Red clover was more sensitive to intraspecific competition than it was to interspecific competition with ryegrass.
Literatkre responded to P hybtidus as would be expected based on the results of Sanchez et al. University of Florida Rights Management: While there is some evidence of a positive response to P application, this was not the case in the fall experiment Table 3.
Literature review on amaranthus hybridus – Don’t have time to do homework
Spiny amaranth generally grew as well with or without the addition of P fertilizer. In addition, this approach also permits analysis of competition using the synthetic no- interaction approach Roush et al.
Critical concentrations in lettuce tissue have been established for these nutrients Sanchez et al. While the replacement series technique is generally applied to biomass or yield, Hall’s approach is to also look at nutrient content in plant tissue. Losses in crop yield or quality from interactions among weeds and crops form the basis of modern weed science Radosevich, It was applied to studies on competition between groundsel Senecio vulgaris L.
The predominate factor which influenced nutrient concentrations in spiny amaranth was duration of weed interference. Under each of the weed densities, untrimmed and trimmed lettuce yields decreased in quadratic fashions with increased duration of weed interference.
Nutritional status while competition is occurring, rather than after it has occurred, can be of greater value in assessing the importance of mineral nutrition on competition Glauninger and Holzner, In the fall experiment Mg concentrations showed a response to duration of weed interference but not to the other experimental factors Table 3.