Canadian Public Administration

ABSTRACTIn many countries around the world, weed infestations poses a significant obstacle to agricultural production and economic activity. However, these weeds are only considered for extermination, and their vast biomass is not utilized effectively. In this study, we attempted to convert weeds into regenerated cellulose fibers for high‐added value and effective use. Cellulose pulp obtained from herbaceous plants (Poaceae) of Andropogon virginicus and Miscanthus sinensis was dissolved in an ionic liquid (1‐butyl‐3‐methylimidazolium chloride) to regenerate cellulose fibers. The properties and morphology of the regenerated cellulose fibers were evaluated, and the structure of the cellulose pulp obtained as an intermediate product was analyzed. The different extraction rates of these weeds resulted in differences in the degree of polymerization of the cellulose pulp. However, the regenerated cellulose fibers were successfully spun in both species. As the speed increased, the regenerated cellulose fibers became smoother, the fiber diameter decreased, and their mechanical properties improved. The regenerated celluloses fiber obtained from M. sinensis were comparable to rayon, an existing cellulose fiber, and exhibited similar values of fiber strength and modulus. These results indicated that the production of regenerated cellulose fibers from unused weeds was effective. This study demonstrates the potential of this materials as a new raw material.

ABSTRACTVerbesina encelioides is known to threaten the performance of crops like common bean in central rift valley of Ethiopia. A field experiment was conducted to investigate the effect of management on V. encelioides and common bean yield components and yield at Adamitulu and Melkassa. A randomized complete block design with four replications and twelve treatments was applied. Treatments included pre and postemergence herbicides (s‐metolachlor, pendimethalin, and sodium acifluorfen + clodinafop propargyl) and hand weeding. The density and biomass of V. encelioides were reduced by up to 94% and 81%, respectively, due to integrated control treatments. Beside the weed‐free plot, the use of s‐metolachlor plus hand weeding and pendimethalin plus hand weeding produced the lowest (3%–10%) weed index. Whereas these integrated controls gave the highest (74%–81%) weed control efficiency. Weed‐free plots yielded the highest grain (3.11 and 2.71 t/ha), followed by s‐metolachlor with two hand weedings (3.00 and 2.63 t/ha), while weedy check (0.49 and 0.45 t/ha) and sole pendimethalin 1.5 l/ha (1.28 and 1.12 t/ha) produced the least grain yield at Melkassa and Adamitulu, respectively. The use of s‐metolachlor plus one‐hand weeding, followed by two‐hand weeding, produced a maximum benefit‐cost ratio of 28.41 and 26.95 and an acceptable maximum marginal rate of return of 5689.06 and 5057.27 ETB, respectively. Thus, it is recommended that smetolachlor be used with one‐hand weeding followed by two‐hand weeding or sodium acifluorfen + clodinafop propargyl at 1 l/ha to achieve effective control, higher yield, and economic benefit in common bean production systems.

ABSTRACTConventional weed management is known for the use of selective herbicides, tackling issues of herbicide‐resistant weeds, and endeavors to reduce reliance on herbicides, such as employing biological control of weeds and incorporating allelopathy. These strategies are integrated with traditional and other conventional weed management techniques. New challenges in agricultural production, such as declining population involved in agriculture, global warming, and climate changes make conventional weed management inadequate. Rapid advancements over the past decade in artificial intelligence (AI), unmanned aerial vehicles (UAVs), cameras, and sensors, necessitate the development and implementation of smart weed management (SWM) approaches for the 21st century. Wise weed management practices can control weeds and reduce emissions of methane (CH4), carbon dioxide (CO2), and nitrogen dioxide (NO2). Minimizing the use of herbicides in tandem with the application of smart technologies, like weed mapping and identifying spatial variability of weeds using proximal and remote sensors, multispectral and RGB cameras, can effectively manage weeds while also reducing labor costs. The SWM strategies also encompass the integrated use of organic herbicides, bioherbicidal products, and the judicious application of both organic fertilizers and inorganic fertilizers for weed management. Some approaches, such as alternate wetting and drying (AWD), can contribute to both SWM and carbon credits to farmers. The utilization of computing power, weed control robotics, and big data, combined with the education of the next generation of weed scientists and efforts to shift growers' attitudes and behaviors in weed management, may vary among countries. It requires active collaboration between agricultural extensionists and policymakers.

AbstractStriga hermonthica is the most devastating parasitic weed affecting the productivity of cereal crops in Sub‐Saharan Africa. The key challenge for controlling this weed is identifying the optimal management strategies that simultaneously reduce Striga infection while boosting crop productivity. This study aimed to evaluate the potential role of intercropping, vermicompost, and seedbed types on the level of S. hermonthica infestation and sorghum productivity in 2021 and 2022 years. The treatments consisted of three factors: (i) three sowing methods (sole‐cropped sorghum (SS), intercropped sorghum with Babile‐1 (SB1), and Babile‐2 (SB2) groundnut varieties); (ii) four levels of vermicompost (0, 1.5, 3.0, and 4.5 t/ha); and (iii) two seedbed types (open‐furrow and tied‐ridge). The results indicated that pure‐stand sorghum in open‐furrow planting without fertilizer had the tallest height (60 cm), the heaviest dry weight (39 g) as well as the highest Area under Striga Number Progress Curve (ASNPC) (>1200) in the first year with substantial reduction in successive year. The combination of 4.5 t/ha vermicompost, tied‐ridge, and groundnut intercropping gave the maximum sorghum panicle weight (151 g/plant), stover yield (14.21 t/ha), and grain yield (6.01 t/ha) in the year 2022. The greatest grain yield observed at 4.5 t/ha vermicompost under tied‐ridge with SB2 was nearly three times higher than the plot without vermicompost application. This treatment combination significantly suppresses S. hermonthica infestation while improving sorghum yield attributes. Thus, it could reduce food insecurity in the lowlands of Ethiopia via improving sorghum productivity, resources use efficiency, and soil health.

AbstractHordeum spontaneum is a winter annual weed that reduces crop yields in Iran. The aim of this study was to quantitatively analyze the effects of burial on seed longevity and germinability and of water potential and temperature on germination. Seeds were placed in nylon‐mesh bags and buried in soil in a semi‐arid region on 1 July 2018 and exposed to natural temperature regimes. After 2 months of burial, seed viability started to decline with a slope of 0.0169%, and after 9 months all seeds were nonviable. Fresh seeds were dormant, but became non‐dormant during summer via dry after‐ripening. Thus, by late autumn (December) the seeds germinated to 100% in dark at 5 and 15°C. The base, optimum, and ceiling temperatures were 0.27, 17.5, and 25°C, respectively, at a water potential of 0 MPa. The hydrotime constant was 50.6–426.9 MPa h, base water potential −1.23 to −0.333 MPa and hydrothermal constant 1350.5 MPa °C h. These results can be used to predict timing and extent of weed emergence of H. spontaneum in crops and in planning for sustainable management strategies.

AbstractSagittaria trifolia, a perennial weed of Alismataceae in Japanese rice paddies, has a single ALS gene, and both target and non‐target‐site resistance are known in the SU resistance of this species. In this study, the target‐site resistance profile at the whole‐plant and enzyme levels was investigated using self‐pollinated S1 seedlings from a parent plant heterozygous for a Pro197Ser ALS mutation and their clonal tubers. Our objectives were to reveal differences and similarities between whole‐plant resistance of seedlings to imazosulfuron and that of tuber‐derived plants and to correlate the whole‐plant responses to enzymatic inhibition, as well as to quantify the effects of mutant ALS allele stacking. Genotyping confirmed a Mendelian segregation ratio (1:2:1) among S1 plants for wild‐type, heterozygous, and homozygous ALS mutations. Enzymatic assays showed that resistance correlated with the number of mutant alleles, and heterozygous plants exhibited a double‐sigmoid curve plateauing at 50%, indicating the function of a 50:50 wild‐type to mutant enzyme ratio. Studies of tuber‐derived plants showed that resistance increased with more mutant alleles, but with a disproportionate jump over 3000‐fold from wild‐type to heterozygous, and only 5‐fold from heterozygous to homozygous, indicating a saturating tendency in the stacking effect of mutations. The dose response of S1 seedlings was consistent with Mendelian segregation of genotypes and suggested a similar saturation of resistance increase due to allele stacking as observed in tubers, with comparable dose–response patterns across identical genotypes.

AbstractA field experiment was conducted in Samastipur district of Bihar, India during kharif season of 2021 and 2022 to identify suitable herbicides for control of composite weed flora in direct seeded rice. Compared to weedy check, application of bispyribac sodium + pyrazosulfuron ethyl as tank mixture effectively reduced weed density at 50 days after seeding during both the cropping season (82% and 86%, respectively) and weed dry weight (7.62 and 7.18 g m−2, respectively) over control and as a result yielded maximum during both the cropping season (47.92 and 51.32 q ha−1, respectively). Based on overall performance, bispyribac sodium + pyrazosulfuron ethyl may be considered as viable weed management option in direct seeded rice for the rice growers of middle Indo‐Gangetic region.

AbstractOceanic islands are a major tourist destination, and the invasion of exotic plants on oceanic islands is a serious problem. To discuss how exotic herbaceous plant invasion is driven by human disturbance on an oceanic island, we assessed the distribution patterns of exotic herbaceous species along a metropolitan road, including parking lots, on the island of Chichijima in the Ogasawara Islands of Japan in the North Pacific Ocean. We observed 16 exotic herbaceous species representing seven families, and all the species have also been recorded in surveys 25 years ago. Species richness (number of species per plot) ranged from 0 to 9 with an average of 2.49. Distance from a parking lot was significantly negatively related to the distribution patterns of seven species and positively related to three species, pointing to parking lots being critical nodes along the dispersal pathways of exotic herbaceous species in Chichijima. Although roads are well known to play an important role as corridors for the invasion and seed dispersal of exotic plants, our results suggest that it would also be important to consider the location of parking lots to understand the distribution of exotic herbaceous species in road networks. We suggest that intensive weed management near parking lots and car wash protocols on Chichijima may be effective in halting exotic species spread.

AbstractThe persistence of a soil seed bank influences weed management options. However, for many species, the degree of persistence of a soil seed bank is unknown. We assessed how long seeds remain in the soil for two invasive weeds, Chrysanthemoides monilifera subsp. monilifera (boneseed) and C. monilifera subsp. rotundata (bitou bush), as seeds of these species were predicted to have different longevity in the soil associated with differences in seed coat thickness. Seeds of both subspecies were buried at two depths at two sites in eastern Australia. Seeds were tested for germinability and viability regularly over an 8‐year period. Freshly collected seeds had quite low viability, and there was a rapid decline in viability in the first couple of years after burial, with C. m. rotundata declining faster than C. m. monilifera. Some seeds, however, remained viable in the soil at some sites for up to 8 years, with high site‐to‐site variability. The variability in viability from site to site may be due to the length of time soils remain moist: a combination of rainfall quantity and humidity levels. The low numbers of seeds remaining viable at 8 years indicate progressively lower probabilities of recruitment at sites following weed control but also suggest that monitoring for both subspecies needs to occur for a long period to minimize the risk of reinfestation from the seed bank.

Abstract4,8‐Dihydroxy‐1‐tetrahydronaphthone (4,8‐DHT), an allelochemical, was isolated from the Carya cathayensis epicarp and was discovered to have phytotoxicity in laboratory tests. In this study, field experiments were designed to assess the phytotoxicity of 4,8‐DHT on weeds in Cerasus yedoensis and Lagerstroemia indica forestlands after pre‐ and post‐emergence application, in addition to physiological effect on Lindernia procumbens were also measured. The phytotoxic results of 4,8‐DHT demonstrated that the total inhibition rate of weeds was 81.3% and 68.2% in C. yedoensis forestland and L. indica forestland after pre‐emergence applied for 24 days in 2021, and enhanced by 9.9% and 27.8% compared with post‐emergence treatment. Especially, in C. yedoensis forestland, a high concentration of 4,8‐DHT sprayed at the pre‐emergence stage after 8 days had a significant inhibition rate on all weeds except Cyperus rotundus, and was still above 80.0% after 24 days of exposure. Comprehensive control efficacy of 4,8‐DHT indicates that pre‐emergence application is more favorable for weeds control. Physiological analysis showed that 4,8‐DHT stimulated the contents of thiobarbituric acid reactive substances (TBARS), hydrogen peroxide (H2O2), and proline and declined in the activities of antioxidant enzymes, meanwhile, accompanied by a decrease in the root vitality and chlorophyll content in L. procumbens. These results warrant further investigations of 4,8‐DHT applied in early pre‐emergence as a potential source of weed control agent.

AbstractOcimum sanctum is a leaf‐vegetable and spice crop with several nutritional, therapeutic, and curative properties. Economic losses due to weeds have posed a major challenge to farmers, who have adopted different techniques to manage weeds without regard to its effect on the crop's nutritional qualities. The objective of this study was to investigate the effect of weed control techniques on weed eradication, leaf yield, and nutritional qualities of O. sanctum. Nine weed control techniques comprising black, red, and transparent polyethylene mulches, rice husk and sawdust mulches, daily removal of weed (DROW), hoe‐weeded, application of Haloxyfop post‐emergence herbicide spray (PEHS), and un‐weeded were investigated in a randomized complete block design with three replications. Significant variations in leaf‐yield and nutritional qualities among the different weed control techniques were recorded. Leaf yield was higher in plots treated with rice husk and black polyethylene mulches. Haloxyfop PEHS and transparent polyethylene mulch were superior in enhancing the proximate and vitamin contents of O. sanctum while black polyethylene and DROW were more efficient in weed control compared with the other weed control techniques. The use of polyethylene mulch as an effective weed management option offers numerous benefits for agriculture and gardening. Its ability to conserve moisture, suppress weed growth, and improve the crop microclimate, makes it a sustainable and cost‐effective option for farmers globally. Additionally, the use of herbicide to exploit plant biosynthetic pathways could lead to the unearthing of chemical innovations that could in addition to eradicating weed, also improve the nutritional qualities of crop.