Showing 7 results for Weeds
N. Torbatinejad, J. R. Sabin,
Volume 3, Issue 2 (4-2001)
Abstract
In the first experiment, twelve species of the most plentiful and fresh seaweeds and one
species of seagrass from the beach were collected at Kingston, South Australia. All species
were then separately sun-and oven-dried and ground. The ground samples were analysed
for dry matter, ash, organic matter, crude protein, crude fibers, ether extract and digestibility
in vitro. The digestible and metabolisable energy of the samples were estimated by
calculation. The results showed that all seaweeds and seagrasses contained a very high ash
content, ranging from 19.5 - 40 per cent. The crude protein content of the samples was
low and ranged from 4.4 - 7.3 per cent. The crude fiber in seagrass was considerably
greater than in seaweed species (34.4 % vs 3.7 -10.1 %). The dry matter digestibility of
samples ranged from 34.1 to 51.5, while the data also showed that the values for digestible
and metabolisable energy of aquatic plants were very low as compared with lucerne (the
control). From the first experiment it was concluded that, amongst marine plants available
in South Australia, the seagrass Posidonia australis, because of its ready availability
in great quantities and the environmental problems for residents, may be regarded as a
potential alternative animal feedstuff. In the second experiment, samples of four different
physical forms of seagrass, Posidonia australis green and fresh (from the water, and
washed and un-washed from on the beach) were examined and compared for their chemical
composition, including nonstarch-polysaccharides, uronic acids, neutral detergent fiber,
acid detergent fiber and lignin, amino acids, crude protein, tannin, ether extract,
soluble and insoluble ash. The results from this experiment showed that there were no
significant differences between the four different physical forms of seagrass collected in
terms of their most important chemical constituents.
Volume 5, Issue 1 (6-2016)
Abstract
Extracted polysaccharides from green seaweeds are heterogeneous in structural and molecular properties. Basically, sulfated polysaccharides from green seaweeds contain various amounts of rhamnose (16.5-45.0%), xylose (2.1-12.0%), glucose (0.5-6.4%) and sulfate (16.0-23.2%), and their building blocks are chiefly comprised of β-D-GlcpA-(1 → 4)α-L-Rhap3s. Molecular weight of sulfated polysaccharides varies from 93.4 × 103 to 1690 × 103 g/mol. The biological effects of seaweed sulfated polysaccharides are immunomodulation, cancer cell growth suppression, antioxidation, antihyperlipidemic, antiviral and anticoagulation. As the chemical structure and molecular properties of sulfated polysaccharides differ from one seaweed species to another, the biological properties varies subsequently. Overall, given the fact that highly variable marine environment can significantly incorporate into the existing discrepancies of sulfated polysaccharide structures due to seaweed phylogenetic differences, executing more comprehensive studies on various species is necessary to have a better understanding of their function and future applications
Volume 9, Issue 4 (8-2020)
Abstract
It is possible to increase the efficacy of herbicides by adding vegetable oils to the spray tank. In order to evaluate and study this fact a greenhouse study was conducted. Three vegetable oils (coconut, sesame and almond oils at 0.3% (volume/volume)) were applied to compare their influence on enhancing the efficacy of pinoxaden and haloxyfop-R-methyl in 2012. The experimental design was completely randomized design with six replications in a factorial arrangement for each herbicide. The treatments were two herbicides, three adjuvants + untreated or control. The two herbicides were pinoxaden and haloxyfop-R-methyl that were divided into six doses (0, 6, 12.5, 25, 50 and 100 percent of recommended doses) and applied with and without vegetable oils to control littleseed canary grass. Moreover, dose–response experiment was carried out for any applied herbicides. The results of experiment revealed that by adding all vegetable oils haloxyfop-R-methyl ester weed suppressing influence was increased more when it is compared to pinoxaden that was attributed to a positive relationship between oil receptivity and the high octanol–water partition coefficient of haloxyfop-R-methyl ester herbicide. Among evaluated vegetable oils, coconut oil owned highest ability to enhance the efficacy of two herbicides which is probably due to high saturated / unsaturated ratio of fatty acids. In addition to, the comparison of vegetable oils’ effects on efficacy of herbicides demonstrated that better performance of coconut oil is probably related to the existence of short-chain fatty acids in coconut oil particularly, Caprylic, Capric and Lauric.
Volume 10, Issue 3 (10-2022)
Abstract
Aims: Monitoring variations in macroalgal assemblages is a crucial issue for the preservation and management program of coastal waters. This study was conducted to determine the seasonal and spatial distribution patterns, and composition of macroalgal communities along the eastern coasts of Qeshm Island, Iran.
Materials & methods: Seasonal sampling was conducted at three different sites of different tidal levels on the eastern coasts of Qeshm Island. Random samples of macroalgae were collected at three stations, seasonally. The species were identified and the dry weight of each species was used to calculate the macroalgae abundance. The Species richness and the Diversity indices were calculated to evaluate the distribution pattern and composition of the macroalgal community.
Findings: As a result, 51 species (4 Chlorophyta, 21 Phaeophyta, and 26 Rhodophyta) were identified. The seasonal and spatial dominant species were found to be Padina sp. and Hypnea sp., and a distribution pattern was seen to have increasing macroalgal biomass from the upper to lower intertidal level. The sampling sites shared more than 50% similarity of their macroalgal species, indicating a relatively homogeneous distribution. The highest (18.1±4.3 gr drywt m-2) and lowest (8.27±2.1 gr drywt m-2) mean of total seaweed biomass were recorded in winter and summer, respectively.
Conclusion: The assemblage composition of macroalgae significantly differs between hot and cold seasons, and there was no substantial compositional variation of seaweeds communities along the tidal gradient. The macroalgal distribution was largely homogeneous with no significant difference among the research areas at sampling seasons.
H. Hamzehzarghani, S. A. Kazemeini,
Volume 13, Issue 7 (12-2011)
Abstract
The performance of different yield loss models from an exponential family was evaluated in safflower-redroot pigweed systems in two field experiments conducted during 2007 and 2008 growing seasons at the research field of Agricultural College of Shiraz University, Iran. The yield loss of safflower was recorded as relative yield loss in experimental plots laid out in split plot design with three replicates. Three different irrigation treatments were allocated to the main plots and consisted of full irrigation or 100% field capacity (FC), 75% FC, and 50% FC, while five weed densities (0, 3, 6, 9, and 12 weeds m-2) were assigned to the sub-plots The Logistic and Gompertz models and a user defined Power-Exponential model were fitted to the data to relate crop yield loss to the weed densities under different water stress conditions. The Power-Exponential model was chosen as the best fit to the data with statistically acceptable model diagnostics. Logistic and Gompertz models showed good fit to the observed data, but underestimated the yield loss under three levels of irrigation. Model performance in all cases was influenced by water stress as models generally showed greater constant and systematic biases under severe water stress (50% FC). Model parameters were used to explain the impact of water stress in crop/weed system. The exponential family models globally performed better over common empirical models such as Spitters, Kropff and Lotz and Cousens models.
A. Wozniak, C. Kwiatkowski,
Volume 15, Issue 7 (12-2013)
Abstract
The aim of this study was to evaluate the effect of long-term reduced tillage on yield and weeds of spring barley. Treatments consisted of three tillage systems including: (a) conventional tillage (CT), (b) reduced tillage (RT), and (c) herbicide tillage (HT) as the main plot, and two cultivars of spring barley (Tocada and Rastik) as subplots. The results showed that the yield of both cultivars was the highest in CT and the lowest in HT and RT tillage systems. Yield reductions in both HT and RT tillage systems were due to lower spikes per m2 and 1,000 grain weight. Weeds numbers and dry weight were more in HT and RT than CT tillage.
H. Ghanizadeh, K. Harrington, T. James, D. Woolley, N. Ellison,
Volume 18, Issue 4 (7-2016)
Abstract
Glyphosate resistance has been found in two populations of Italian ryegrass (Lolium multiflorum) following many years of glyphosate application in New Zealand vineyards. Dose-response experiments showed that both glyphosate-resistant Italian ryegrass populations had 10-fold levels of resistance to glyphosate compared to a susceptible population. Possible mechanisms of glyphosate resistance target site mutation at position Pro-106 of 5-enolpyruvyl-shikimate-3-phosphate synthase gene and alterations in glyphosate absorption/translocation in these populations were investigated. Genotyping assays demonstrated that there was no point mutation at Codon 106 of the 5-enolpyruvyl-shikimate-3-phosphate synthase gene in either of the resistant populations. Glyphosate-resistant and susceptible populations did not differ in 14C-glyphosate absorption. However, in both resistant populations, much more of the absorbed 14C-glyphosate was retained in the treated leaf than occurred in the susceptible population. Significantly more 14C-glyphosate was found in the pseudostem region of susceptible plants than resistant plants. Based on these results, it was suggested that alterations in glyphosate translocation patterns plays a major role in glyphosate resistance for Italian ryegrass populations from these New Zealand vineyards.