Effects Of Imazethapyr Research Articles

Imazethapyr disrupts plant phosphorus homeostasis and acquisition strategies

The deficiency of essential mineral nutrients caused by xenobiotics often results in plant mortality or an inability to complete its life cycle. Imazethapyr, a widely utilized imidazolinone herbicide, has a long-lasting presence in the soil-plant system and can induce toxicity in non-target plants. However, the effects of imazethapyr on mineral nutrient homeostasis remain poorly comprehended. In this study, Arabidopsis seedlings exposed to concentrations of 4 and 10 μg/L imazethapyr showed noticeable reductions in shoot development and displayed a distinct dark purple color, which is commonly associated with phosphorus (P) deficiency in crops. Additionally, the total P content in both the shoots and roots of Arabidopsis significantly decreased following imazethapyr treatment when compared to the control groups. Through the complementary use of physiological and molecular analyses, we discovered that imazethapyr hinders the abundance and functionality of inorganic phosphorus (Pi) transporters and acid phosphatase. Furthermore, imazethapyr impairs the plant's Pi-deficiency adaptation strategies, such as inhibiting Pi transporter activities and impeding root hair development, which ultimately exacerbate P starvation. These results provide compelling evidence that residues of imazethapyr have the potential to disrupt plant P homeostasis and acquisition strategies. These findings offer valuable insights for risk assessment and highlight the need to reconsider the indiscriminate use of imazethapyr, particularly under specific scenarios such as nutrient deficiency.

Effects of Imazethapyr on Soybean Root Growth and Soil Microbial Communities in Sloped Fields

The herbicide imazethapyr was previously recommended for controlling weeds in soybean fields. However, the effects of imazethapyr on soil microbial communities and their relationship with crop root growth in sloped soils remain unclear. In this study, a field experiment was conducted on a sloped field to explore the effects of imazethapyr on crop root growth, microbial communities, microbial co-occurrence networks, and the interactions between microbes and crop root growth. The field experiment included two factors: slope and imazethapyr. The slope factor included three different slope gradients: 5° (S1), 10° (S2), and 15° (S3). The imazethapyr factor included two treatments: with (I1) and without (I0) imazethapyr. Thus, six total combinations of slope and imazethapyr treatments were tested in this study: S1I1, S2I1, S3I1, S1I0, S2I0, and S3I0. The results show that, compared to the I0 treatments, the I1 treatments significantly increased the soybean root length, surface area, and volume by 11.7~26.5 m, 171.7~324.2 cm2, and 1.8~3.1 cm3, respectively, across all the slopes. The Proteobacteria, Actinobacteriota, and Bacteroidota bacterial phyla and Ascomycota and Basidiomycota fungal phyla were found to be the top phyla represented bacterial and fungal communities. These five phyla were scattered in co-occurrence networks of bacterial and fungal communities, suggesting these phyla play critical roles in enhancing the stability of co-occurrence networks. Compared to the I0 treatments, the I1 treatments increased nodes from Proteobacteria, Actinobacteriota, and Bacteroidota phyla by 6.4%, 9.1%, and 11.2%, respectively, in the bacterial co-occurrence network. Similarly, in the fungal co-occurrence network, the I1 treatments improved nodes from Ascomycota and Basidiomycota phyla by 1.8% and 5.8%, respectively. Compared to the I0 treatments, the I1 treatments increased positive relations by 8.3% and 3.2%, respectively, in the bacterial and fungal co-occurrence networks. Moreover, the I1 treatments increased the relative abundance of root-promoting biomarkers and suppressed root-limiting biomarkers. However, the application of imazethapyr reduced the diversity and richness of bacterial and fungal communities in general. Furthermore, the nodes and links of bacterial co-occurrence networks in the I0 treatments were 9.2% and 78.8% higher than these in the I1 treatments. Similarly, the I1 treatments also decreased 17.9% of fungal community links compared to the I0 treatments. Our data also show that compared to the I0 treatments, the I1 treatments decreased almost all gene families encoding nitrogen and carbon cycling pathways. In conclusion, the application of imazethapyr increased soybean root growth by increasing root-promoting biomarkers and improved the stability and cooperation of co-occurrence networks of bacterial and fungal communities. However, the application of imazethapyr had some negative impacts on microbial communities, such as reducing the diversity of bacterial and fungal communities and nitrogen and carbon cycling pathways.

Effects of imazethapyr treated oil palm frond residue mulch on weed control and ornamental plant quality in nurseries

A combination of oil palm frond (OPF) mulch and imazethapyr has been shown to provide good weed control in crop plantations, but information on its potential use for weed control in nurseries is limited. This study aims to evaluate the effect of imazethapyr in combination with OPF mulch on the inhibition of goosegrass, slender cyperus, coat buttons and phytotoxicty on ornamental plants under glasshouse conditions. Three suboptimal rates of imazethapyr, representing low, medium and high rates, are applied alone or used to treat 3.5 t ha−1 OPF residue powder (< 2mm). The low rate of imazethapyr at 10 g a.i. ha−1 and the OPF mulch alone inhibit seedling growth of goosegrass, slender cyperus and coat buttons by 40%-60%. The OPF mulch treated with imazethapyr at this rate acts synergistically and provides 80%-95% inhibition ofweed growth. However, increasing the rate of imazethapyr over 10 g a.i. ha−1 does not further improve weed inhibition, and results in antagonism on goosegrass and slender cyperus emergence. A subsequent experiment with the low rate of imazethapyr incorporated with OPF mulch causes moderate phytotoxicity on Chinese aloe and coral swirl, but minimal or no injury was observed for jasmine, cactus, puding and euodia at 4–12 weeks after treatment. Results suggest that incorporation of imazethapyr at 10 g a.i. ha−1 with OPF mulch can effectively control goosegrass, slender cyperus and coat buttons without injuring jasmine, cactus, puding and euodia.

Impact of imazethapyr on the microbial community structure in agricultural soils

Large amounts of imazethapyr were applied for weed control in cultivation fields in China, but their effects on the soil microbial community remains unclear. In this study, two agricultural soils, a silty loam (HS) and a loamy soil (QL), were spiked with imazethapyr (CK, 0.1, 1 and 10 mg kg −1) and incubated for 1, 15, 30, 60, 90 and 120 d. In addition, untreated controls received only water. The soil microbial community structures were characterized by investigating the phospholipid fatty acids (PLFA) and microbial biomass C. Soil microbial biomass C and total concentration of PLFA were variable with incubation time, which were also reduced by the addition of imazethapyr. Imazethapyr addition also decreased the ratios of GN/GP and fungi/bacteria. A larger stress level, measured as the ratio of PLFA (cyc17:0 + cyc19:0)/(16:1 ω7c + 18:1 ω7c), was found in the high concentration (1 and 10 mg kg −1) herbicide treatment groups. The effects of imazethapyr at the field application on soil microbial biomass and microbial community were minor. Principal component analysis (PCA) of the PLFA clearly separated the treatments and incubation times. Both soils showed different total PLFA concentrations and ratios of GN/GP and fungi/bacteria, but similar changes in the PLFA pattern upon soil treatment. The soil microbial community structure was shifted by the addition of imazethapyr, which recovered after 60 d. In addition, the dissipation of imazethapyr was slow in both soils. Our results demonstrated that the addition of imazethapyr shifted the microbial community structure, but that it recovered after a period of incubation.

Soil Persistence of Imazethapyr and Detection Using a Sensitive Bioassay Technique

The effects of imazethapyr on root growth of vegetable crops were compared between a lab bioassay and vegetative crop growth in field plots. In the bioassay study, at 5 d after seeding, the lowest imazethapyr rates to cause significant root length reduction of table beets (Beta vulgaris L. 'Early Wonder'), cabbage (Brassica oleracea L. 'Bravo'), cucumber (Cucumis sativus L. 'Marketmore 76'), and sorghum [Sorghum bicolor (L.) Moench 'Corral'] were 0.5, 2.5, 10, and 25 ppb (w/w soil), respectively. In the field, where crops were planted 5 d after preplant incorporated (PPI) herbicide application, the lowest rates to cause dry shoot weight reduction of table beets, spinach (Spinacia oleracea L. 'Seven-R'), cabbage, cucumber, and sorghum were 0.005, 0.01, 0.025, 0.025, and 0.025 lb ai/acre, respectively. These rates are approximately equivalent to concentrations of 5 and 10 ppb respectively for table beets and spinach; and 25 ppb for cabbage, cucumber, or sorghum, based on a 4-in. topsoil weighing 1 × 10 6 lb. However, cabbage planted into treated plots 4 and 12 mo after herbicide application was not injured. In field soil samples collected at monthly intervals starting 45 d after herbicide application (DAHA), imazethapyr at 0.0025 to 0.05 lb ai/acre was not detected beyond 75 DAHA using beet root growth as herbicide indicator. However, at 0.10 lb ai/acre the herbicide persisted until 105 DAHA but was not detected 135 DAHA.

Effects of the herbicide imazethapyr on soil microbial biomass and various soil enzyme activities

The effects of imazethapyr, an imidazolinone derivative on the soil microbial biomass was investigated in a clay loam soil. Imazethapyr was applied in a field trial at the recommended field rate for soybean weeding, 50 g a.i. ha-1. In laboratory experiments the herbicide was incorporated at the field rate and 10-fold and 100-fold higher. In both the field trials and the laboratory experiments, the field rate of imazethapyr had no adverse effects on the microbiological processes tested. But at 10-fold and 100-fold higher rates, the herbicide decreased the biomass-C content and dehydrogenase activity and increased the hydrolytic capacity and protease and catalase activity. These findings suggest that there may be a risk in monocultural practices that require repeated herbicide treatments.