Effect of reduced doses of a post-emergence graminicidal mixture to control Lolium rigidum G. in winter wheat under direct seeding in a Mediterranean environment (2023)

Fennel is widely used in traditional medicine for its antimicrobial effects. Because fennel is a perennial crop and has slow initial growth, weed control is essential. Experiments were conducted over two consecutive seasons to evaluate the effectiveness of soil-applied herbicides at reduced rates in combination with physical control for weed management and fennel yield optimization. The treatments were herbicide type (trifluralin and pendimethalin), application rate (recommended rate (R), 75% R, 50% R and 0% R) and physical weed control (none, one manual weeding 50 days after planting (DAP) ), mulch of wheat straw). A weed-free control was also included in each year. The results showed that the use of soil-applied herbicides resulted in reduced weed biomass, but did not provide season-long weed control without additional physical control. In both seasons, pendimethalin gave better weed control than trifluralin. Reduced herbicides were found to be more effective when the herbicides were applied followed by hand weeding than when they were used alone or in combination with mulch. Experimental results also showed that a one-time increase in herbicides increased seed yield by 17.5 and 7.5% in 2012 and by 16.5 and 6.3% in 2013, when manual weeding and mowing, respectively, were used as additional controls. In general, 75% of the label recommended rate of herbicides followed by one manual weeding at 50 DAP produced consistently high yields and reduced weed biomass, reflecting both superior weed control and crop safety.

Three field experiments were conducted in the research areas of Plant Protection Research Institute, Iran, at different locations in 2004–2005 to investigate the effectiveness of different broadleaf herbicides for weed control in wheat. Treatments included hand-weeded and weed-infested controls throughout the season and post-emergence applications of florasulam plus flumetsulam at 8.75, 10.50 and 12.25 ga.i./ha, 2,4-D plus carfentrazone-ethyl at 210, 245, 280 and 490 ga.i./ha, bromoxynil plus MCPA at 75, 100 and 150 ga.i./ha, 2,4-D at 560, 720 and 1120 ga.i./ha, tribenuron methyl and 2,4 -D plus MCPA. Herbicides were applied during wheat germination. Naturally occurring broadleaf weed populations were used in experiments. The results showed that bromoxynil plus MCPA at 150 ga.i./ha, 2,4-D plus MCPA, and 2,4-D plus carfentrazone-ethyl at 490 ga.i./ha were the best options for weed control. Bromoxynil plus MCPA at 150 ga.i./ha and 2,4-D plus MCPA also resulted in the highest wheat yield. Overall, it can be concluded that alternative application of bromoxynil plus MCPA at 150 ga.i./ha, 2,4-D plus MCPA and 2,4-D plus carfentrazone-ethyl at 490 ga.i./ha is the best would be. possibility of achieving satisfactory weed control, high grain yield and prevention of weed-resistant weed development.

Field experiments were conducted in the research fields of the Plant Protection Research Institute, Iran, at six sites in 2005–2006 to investigate the weed control performance of some newly registered herbicides in wheat compared to some current herbicides. Treatments consisted of post-emergence applications of chlorsulfuron at 10.5 and 15 ga.i./ha, metsulfuron methyl plus sulfosulfuron at 32 and 36 ga.i./ha, both as dual-purpose herbicides, pinoxads at 45 and 60 ga. i./ha as grass weed herbicide, pinoxaden at 45ga.i./ha plus nonionic surfactant at 0.2% (v/v), tribenuron-methyl at 18.75ga.i./ha plus clodinafop propargyl at 64ga.i./ha , clodinafop propargyl, bromoxynil plus MCPA, bromoxynil plus MCPA at 600ga.i./ha plus clodinafop propargyl at 64ga.i./ha, prespiration applications of dual herbicide prosulfocarb at 2400 and .i weed/ha and . management. Post-emergence herbicides were used in wheat milling. The results showed that metsulfuron methyl plus sulfosulfuron at 36ga.i./ha is a suitable option for post-emergence control of broadleaf and grass weeds in wheat. This treatment also resulted in nearly the highest grain yield in several locations. The results also showed the importance of different wheat cultivars and environmental conditions on herbicide effectiveness; which is the best control option may vary based on variety and location. Chlorsulfuron and prosulfocarb also did not have significant priority over older herbicides in these trials, so further research is needed to investigate their effectiveness.

Field experiments were conducted in 2004–2005 at five locations in wheat growing areas of Iran to study weed control and winter wheat response to post-germination applications of diflufenican plus MCPA at 0.5, 1 and 1.5 l/ha, clopyralid plus 2.4 - D and fluroxypyr both at 1.5, 2 and 2.5 l/ha, tribenuronmethyl, 2,4-D plus MCPA, bromoxynil plus MCPA and dicloprop-p plus mecoprop-p plus MCPA. The post-emergence application of diflufenican plus MCPA, clopyralid plus 2,4-D and fluroxypyr improved broadleaf weed control compared to other herbicides. The data show that fluroxypyr at 2.5 L/ha caused the greatest reduction in weed populations and biomass in most cases. The efficacy of bromoxynil plus MCPA was generally better than tribenuron-methyl, 2,4-D plus MCPA, and dicloprop-p plus mecoprop-p plus MCPA, although it varied between sites and weed species. The application of diflufenican plus MCPA, clopyralid plus 2,4-D and fluroxypyr resulted in the highest wheat yield of all treatments.

Atmospheric Pollution Research, bind 11, udgave 8, 2020, s. 1386-1395

We measured methane and carbon dioxide fluxes at natural gas wells and undisturbed soils in the Rocky Mountain and Gulf Coast regions of the United States, including production and gas storage wells. We collected both short-term (15 min) and multi-day (between 3 and 8), continuous measurements at 47 well pads and two undisturbed sites. Methane fluxes varied by more than an order of magnitude over periods as short as 30 min (eg, 19–593 mgm)⁻²H⁻¹in one case), and diurnal and seasonal variation was also significant (e.g. change from spring to autumn from 509 to 14174 mgm⁻²H⁻¹). We hypothesize that short-term flux variability was caused by a pulsed flow of methane during its migration through the subsurface. Barometric pressure and well conditions likely affected the fluxes, but we found only weak evidence for this. Bacterial methanotrophy appeared to affect the magnitude and variability of the methane flux. We injected methane into the subsurface at a well, and we found that although the methane and carbon dioxide fluxes and combustible soil gas concentrations increased in response to the injection, the response was not uniform and the fluxes showed high hourly variations despite a constant injection rate. Methane fluxes were generally higher at well bottoms compared to background bottoms (often much higher), and fluxes tended to be higher at wellway locations closer to the wellhead.

Field Crop Research, Volume 209, 2017, pp. 47-57

Remote estimation of leaf nitrogen (N) or pigments using hyperspectral reflectance allows for non-destructive diagnosis of plant N status. Two cultivars of sweet sorghum (Sorghum bicolor [L.] Moench) (Top 76-6 and Dale) were grown at 0, 56, 112, 168 and 224 kgNha⁻¹in 2009 and 2010. Reflectance measurements were linked to plant height, number of nodes in the main stem, leaf N concentration and total chlorophyll content to determine the relationship between these characteristics and crown reflectivity. Canopy reflectance was most sensitive to N-state in the visible region, especially near green (595 nm) and red (701 nm) wavebands. Spectral models with a simple ratio consisting of visible wavebands or wavebands from the visible and near-infrared regions performed better than models developed with only the most sensitive single waveband. Based on cross-validation of spectral models between data from two years and two cultivars, the models predicted with a simple ratio consisting of reflectance (R) ratio at 595 nm vs. 1676nm and 595nm vs. 508 nm, leaf N concentration and chlorophyll content with the greatest accuracy (highest r²and lowest relative error, RE). These simple ratio models were used to develop general spectral models to derive coefficients for estimating leaf N concentration (−66.63 × R₅₉₅/R₁₆₇₆+34,14; R²0.52; RE 16.8%) and chlorophyll content (-49.12×R₅₉₅/R₅₀₈+107,47; R²0.64; RE 17%). The identified spectral models can be used to assess growth, diagnose sweet sorghum N status, and can be useful in making N management decisions for site-specific fertilization applications.

Plant protection, volume 78, 2015, pp. 1-4

This study investigated whether glyphosate-resistant populations of Lolium multiflorum and Lolium perenne from some New Zealand vineyards were still susceptible to glufosinate and amitrole. The plant response of a glyphosate-resistant population of L. multiflorum, population A, and two glyphosate-resistant L. perenne populations, populations J and O, to glufosinate and amitrole were evaluated and compared with susceptible populations in two dose-response experiments. Based on the herbicides that provide 50% growth reduction (GR₅₀values), populations A, J and O were 3.9, 4.5 and 3.8 times more resistant to glufosinate, respectively, compared to the susceptible populations in a glufosinate dose-response experiment. Populations A, J, and O were also found to be 2.9, 5.0, and 13.1 times more resistant to amitrole, respectively, in an amitrole dose-response experiment. Very similar results were obtained when both dose-response experiments were repeated. This is the first confirmed report of weed species that have developed multiple resistances to glyphosate, glufosinate and amitrole. These are the three main herbicides currently used for weed control in New Zealand vineyards.

Agriculture, ecosystems and environment, volume 250, 2017, pp. 1-11

Agricultural land is the main source of nitrous oxide emissions from management practices, including fertilizer application. While the amount of fertilizer is one of the main drivers of nitrous oxide emissions, emissions also depend on other variables, such as climate and soil properties. To understand the spatial and interannual variations in emission rate, simulations of N₂O2 emissions were made from 2000 to 2010 for grass and cropland in the UK. In addition, the sensitivity of these emissions to soil and climate inputs was also tested. Emissions between 0.3 and 3.5 kgNha⁻¹jr⁻¹a 0.7-7 kgNha⁻¹jr⁻¹were simulated in UK cropland and grassland respectively. Although interannual variations can be attributed to climate forcing, the main cause of spatial variations in emissions was soil clay content. However, when testing the sensitivity of nitrous oxide emissions to soil clay content alone, it was not always the best predictor of emissions when soil texture changes outside the normal range used as input to the model from various databases.

Plant Protection, Volume 78, 2015, pp. 106-113

The relationships between vegetation components in perennial pastures are complex, especially those involving grasses, weeds, legumes, and other forbs. When herbicides are used for broadleaf weed control, there may be a trade-off between the benefits of weed removal and the loss of legumes. Few studies distinguish between the contribution of different vegetation components to total forage yield, both before and after spraying. Herein, we use Structural Equation Modeling (SEM) to quantify relationships between grasses, legumes (Medicago sativa L. or Trifolium spp.), a common noxious weed (Cirsium arvense (L.) Scop) and other forbs at two sites within the Parkland -region of central Alberta, Canada. After clearing broadleaf vegetation with herbicide, we quantified changes in forage relative yield ratios (RYR) over two years. The SEM approach revealed clear differences in the ratio of grass components between sites. At the more mesic site, abundant thistle biomass had little influence on other turf components, and no benefit was observed in weed removal after spraying. In contrast, even low levels of thistle biomass suppressed grass and legume biomass at the more extreme site, and response after spraying revealed weed removal benefits. Unexpectedly, legumes were found to suppress grass biomass at both sites, suggesting strong interspecific competition between forage species. Subsequent removal of legumes appeared to release grass biomass from competition within sprayed plots, as illustrated by increased forage yield two years after spraying. These results highlight the complexities within temperate perennial pastures and illuminate the potential short-term effects of weeds and legumes on overall sod dynamics and forage production.

Biomass and bioenergy, volume 95, 2016, pp. 8-18

We have estimated the effect of different cutting heights and harvesting strategies on the amount of harvestable residual biomass and allocation of residual biomass in the soil. A case study has been carried out on regional sources of straw biomass with the different crops currently grown in Varsinais-Suomi (southern Finland) (average from 2003-2012) and in the predicted future warmer climate (scenario RCP 4.5, year 2055) . We also estimated, using the Yasso07 model, the effects of different residual uptake intensities on soil organic carbon (SOC) at present and in the future warmer climate. The results indicated that the cutting height has a significant influence on the amount of straw biomass incorporated into the soil and the subsequent change in SOC. The impact depended on crop type and variety. When collecting and using straw, e.g. in energy production, harvesting methods that create greater stubble heights can help maintain soil fertility. The Yasso07 model suggests that in the predicted future warmer conditions, more straw could be collected without lowering SOC, as SOC mineralization in the warmer climate is expected to increase less than organic carbon changes caused by higher crop and root biomasses. Collecting and using straw as a renewable energy source always lowers greenhouse gas (GHG) emissions compared to fossil fuels. However, collecting straw every other year instead of every year, even with taller stubble, would reduce field traffic and compact the soil, saving the farmer extra work, while also significantly reducing greenhouse gas emissions.