In the experiment no differences were found between the band and broadcast application methods for untrimmed lettuce. The purpose of these studies was to establish P fertility rates to be used in the competition studies. A modified application of the replacement series which enables assessment of competition over a range of densities was proposed by Jolliffe et al. On the other hand, relatively immobile resources, such as phosphorus, would only be taken up from soil in close proximity to roots of the individual plants. Competition between lettuce and spiny amaranth was influenced by P nutrition only in the sense that it was a determinate factor for lettuce growth. Another application of the study of plant competition in agriculture concerns the case in which crop plants grow in mixture with plants that are not part of the intended crop.
The interaction is explored in Table Table 3. There was also some indication that broadcast P application resulted in lettuce being more susceptible to weed interference than did band application Figures 3. Agronomy Department Studies were conducted to determine how spiny amaranth Amaranthus spinosus L. Prior to selecting the field location for each experiment, soil was sampled and analyzed for nutrients as described by Sanchez 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. In light of the findings of these studies, in order to avoid crop loss to competition by spiny 73 amaranth, growers will need to continue to exercise the same weed control practices when using a banded P application system as with the currently used broadcast technique.
Lettuce responded to P application as would be expected based on the results of Sanchez et al. This P concentration response to fertilizer P application by lettuce somewhat parallelled the response of lettuce yields to P application, as previously discussed, for the two spring studies.
It was found amaranthuz be superior for analysis of the influence of proportion on interspecific competition.
Interactions between the experimental factors for Mg concentrations did not appear to be meaningful. It is derived from the initial slope of the relationship between yield and density. In studies with amaanthus peppers, increased weed “cover” resulted in decreased pepper foliage Fe while B, Cu, P and K were increased Frank et al.
Because spiny amaranth grows well at low P, it could be expected to be a good competitor under conditions of low P. This was because soil P in the root 83 microenvironment was not altered by P uptake for a distance greater than 1 mm away from the root.
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.
Losses in crop yield or quality from interactions among weeds and crops form the basis of modern weed science Radosevich, The additive study is the second principle method Cousens, ; Radosevich and Roush, The fact that a mixture responds to nutrient availability, however, does not indicate that the nature of competition within the mixture will necessarily be influenced by alteration of nutrient levels Buckeridge and Norrington-Davies, Information concerning the effect weed infestations have on a crop facilitates the decision making process of when to apply control measures Thill et al.
However, the yield differences obtained in weed-free lettuce for band versus broadcast application suggests that the latter method was slightly superior in the current study. This suggests that spiny amaranth may have been competing with lettuce for P; the more intense competition under the higher spiny amaranth density resulting in lowered P concentrations in lettuce.
Phosphorus uptake variability is known to occur between plants of different species Chapin and Bieleski, ; Hoveland et al. Shoot growth rates decreased within 2 and 6 days after withholding the nutrients N and K, respectively, but not until 9 days in the case of P. In agricultural ecosystems, plant competition is commonly viewed as a factor influencing crop productivity Radosevich and Roush,which implies a shorter term focus than the study of competition in nonagricultural ecosystems would take.
You are commenting using your Twitter account. Lettuce yields in spring and were less 1 a a a. Plants in the family Chenopodiaceae respond so to high nitrate availability.
Soil used in these studies was of low P status soil test value of using the water extractable P analysis based on EREC soil test procedures Sanchez, and had pH values which ranged from 6 to 6. Includes bibliographical references leaves The effects of time, therefore, may be due to a combination of several factors.
The interaction in the spring study did not appear to be meaningful. Interpretation of altered nutrient status of crops due to weed competition is probably dependent on the nature of competition. Biomass of amaranth removed from lettuce at 21 days after plot establishment was greater where P was applied banded or broadcast than where no P applied.
Literature review on amaranthus hybridus – Don’t have time to do homework
On the other hand, relatively immobile resources, such as phosphorus, would only be taken up from soil in close proximity to roots of the individual plants. Studies on applicability of Amaranthus paniculatas Rajgeeraa starch for custard preparation.
Specific treatments used were; 1 no added P, 2 broadcast applied P and 3 band applied P. Just as each of these basic methods has a specific purpose, limitations are also associated with each Cousens, Once this value is obtained a corresponding fertilizer P rate literqture be determined from a calibration curve Sanchez and Burdine, Pelleted lettuce seed was sown in groups of three closely spaced seed every 30 cm of hybidus.
Timing of the onset of deview has also been attributed to nutrient availability, with crop yield loss occurring earlier under high levels of nutrient availability. Falseflax thus competed more strongly for P than flax, both interspecifically and intraspecifically. This was done because correlation of means and residuals was suggested by plotting residual values Freund et al.