Band application of fertilizer P appears to be one means by which nutrient use rates could be reduced without reducing lettuce yields. Alkamper reviewed literature on the combined influence of weeds and fertilization on crop production. Those species exhibiting greatest response to P also showed the most severe deficiency under low P conditions. As P concentration in lettuce tissue increased from 0. Calcium concentrations in lettuce ranged from as low as 1. 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.
The only reduction in 62 P concentration due to increased weed density was for the 35 day duration of weed interference in the spring experiment. Leaves of plant species in which carbon is fixed via the C4 pathway do not generally light saturate at full sunlight. A modified application of the replacement series which enables assessment of competition over a range of densities was proposed by Jolliffe et al. To find out more, including how to control cookies, see here: Broadcast application resulted in greater yields than band application in weed-free lettuce but not where weeds were present for any duration.
Interactions between main effects were assessed using least squares means analysis and paired means comparisons SAS Institute Inc. Spiny amaranth generally grew as well with or without the addition of P fertilizer. Information concerning the effect weed infestations have on a crop facilitates the decision making process of when to apply control measures Thill et al. Under low weed density there was no significant effect of duration of weed interference on lettuce yields.
Field studies in England showed that densities of 65 weeds per m2 resulted in complete loss of marketable yield when weeds were allowed to remain present in the crop Roberts et al. Elberse and deKruyf studied the influence of emergence timing on competition between lambsquarters Chenopodium album L.
In the case of nutrients as the resource for which competition occurs, there are two characteristics which may influence the competitive ability of plants Goldberg, As weed density decreases, individual weeds will have to achieve greater size in order to cause comparable amounts of shading.
Thus, P concentration in spiny amaranth does not appear to have been a limiting factor to growth of the plant, as reflected by biomass, in these studies. They attributed this to a combination of weather conditions being optimal for efficient P use by the plant and to movement of P into the root as soil water Table 3.
Spiny amaranth apparently has a root system which is well adapted to low P conditions. Seeding dates are given in Table 3.
It is not clear why yields were reduced by the low weed density in the spring of but not in The replacement or substitutive series was advanced by the work of de Wit although it was reportedly established prior to this Cousens, These hybrjdus may be the result of reduced plant growth due to others factors becoming limiting rather than an increase in nutrient uptake.
One objective of this investigation was to characterize the effect of interference by spiny amaranth Amaranthus amaratnhus L. One possibility is that lettuce growing under the conditions of the study was more susceptible to the effects of interference by spiny amaranth. With the earliest barley planting, the crop progressively suppressed the weed.
Hybridis factors were CP rate, total density, composition mixture or monoculture and species.
Soil applied herbicides are available for broadleaf weed control in lettuce on mineral soils; however, these are not recommended for use on muck soils Dusky and Stall, Competition was assessed based on analyses of individual plant weight, relative yields, relative crowding coefficients RCC and relative mixture response.
Litsrature more pronounced effect of weed interference on lettuce where P was applied broadcast suggests that lettuce susceptibility bybridus weed interference is greatest where yield is potentially greatest. The possibility of such a response should be kept in mind in studying fertility effects on plants growing in mixture when nutrient additions are made to the rooting media. Samples were thoroughly mixed following grinding and a subsample of the ground material was used for analysis.
It is called keerai masial. The crop responds to each of P and K amendment in a predictable manner on these soils Sanchez and Burdine, You are commenting using your Literture account.
Literature review on amaranthus hybridus
Plants in the family Chenopodiaceae respond so to high nitrate availability. These factors were examined at several fertilizer P application options. There was, however, some difference in how yields and lettuce P concentrations responded to the application method.
Proximity of individual plants to others is directly influenced by density, spatial arrangement and species proportion, which are considered influential factors in the study of interactions between plants. Lettuce responded to P application as would be expected based on the results of Sanchez et al. Instead of being applied to the entire study area, fertilizer P was applied as an experimental treatment.
Literature review on amaranthus hybridus – Don’t have time to do homework
Following removal of spiny amaranth, these plots were maintained free of eeview weeds. With more closely spaced rows the canopy would close earlier. Substantially greater biomass was achieved in the spring Table 3.
Studies in chapter IV concern the determination amaranthhs how P fertility influences the growth of each of the weed and the crop when grown in the presence of one another.