Root Lipid Contents Research Articles

Uptake, Accumulation, and translocation of azoxystrobin by Vegetable plants in soils: influence of soil characteristics and plant species.

Although azoxystrobin has been widely applied on various crops, little is known about the bioavailability of azoxystrobin in the soil-vegetable system. In this study, the uptake, accumulation and translocation of azoxystrobin as affected by soil characteristics and plant species were respectively investigated. The accumulation amount of azoxystrobin in pakchoi increased as soil adsorption decreased and was positively associated with its concentration in pore water (Cpw), which was mainly affected by soil organic matter content. Therefore, Cpw could be a candidate for the estimation of azoxystrobin accumulation in pakchoi. In all the tested vegetables, azoxystrobin was mainly accumulated in roots, and its upward translocation was limited. Root lipid content was a major factor affecting the uptake and translocation of azoxystrobin in different vegetables.

Predicting crop root concentration factors of organic contaminants with machine learning models

Accurate prediction of uptake and accumulation of organic contaminants by crops from soils is essential to assessing human exposure via the food chain. However, traditional empirical or mechanistic models frequently show variable performance due to complex interactions among contaminants, soils, and plants. Thus, in this study different machine learning algorithms were compared and applied to predict root concentration factors (RCFs) based on a dataset comprising 57 chemicals and 11 crops, followed by comparison with a traditional linear regression model as the benchmark. The RCF patterns and predictions were investigated by unsupervised t-distributed stochastic neighbor embedding and four supervised machine learning models including Random Forest, Gradient Boosting Regression Tree, Fully Connected Neural Network, and Supporting Vector Regression based on 15 property descriptors. The Fully Connected Neural Network demonstrated superior prediction performance for RCFs (R2 =0.79, mean absolute error [MAE] = 0.22) over other machine learning models (R2 =0.68–0.76, MAE = 0.23–0.26). All four machine learning models performed better than the traditional linear regression model (R2 =0.62, MAE = 0.29). Four key property descriptors were identified in predicting RCFs. Specifically, increasing root lipid content and decreasing soil organic matter content increased RCFs, while increasing excess molar refractivity and molecular volume of contaminants decreased RCFs. These results show that machine learning models can improve prediction accuracy by learning nonlinear relationships between RCFs and properties of contaminants, soils, and plants.

Uptake kinetics and accumulation of pesticides in wheat (Triticum aestivum L.): Impact of chemical and plant properties.

Plant uptake is an important process in determining the transfer of pesticides through a food chain. Understanding how crops take up and translocate pesticides is critical in developing powerful models to predict pesticide accumulation in agricultural produce and potential human exposure. Herein, wheat was selected as a model plant species to investigate the uptake and distribution of eleven widely used pesticides in a hydroponic system as a function of time for 144h. The time-dependent uptake kinetics of these pesticides were fitted with a first-order 1-compartment kinetic model. During 144h, flusilazole and difenoconazole, with relative high log Kow (3.87 and 4.36, respectively), displayed higher root uptake rate constants (k). To clarify the role of root lipid content (flip) in plant accumulation of pesticides, we conducted a lipid normalization meta-analysis using data from this and previous studies, and found that the flip value was an important factor in predicting the root concentration factor (RCF) of pesticides. An improved correlation was observed between log RCF and log flipKow (R2=0.748, N=26, P<0.001), compared with the correlation between log RCF and log Kow (R2=0.686, N=26, P<0.001). Furthermore, the hydrophilic pesticides (e.g. log Kow < 2) were found to reach partition equilibrium faster than lipophilic pesticides (e.g. log Kow > 3) during the uptake process. The quasi-equilibrium factor (αpt) was inversely related to log Kow (R2=0.773, N=11, P<0.001) suggesting a hydrophobicity-regulated uptake equilibrium. Findings from this study could facilitate crop-uptake model optimization.

The combination of warming and copper decreased the uptake of polycyclic aromatic hydrocarbons by spinach and their associated cancer risk

Both climate warming and co-contamination of polycyclic aromatic hydrocarbons (PAHs) and heavy metals are environmental issues of great concern. However, the interactive effects of warming and heavy metals on PAH accumulation in edible plants and the PAH-associated health risk remain unclear. In this study, enclosed soil/water-air-plant microcosm experiments were conducted to explore the effects of copper (Cu), warming (+6 °C), and their combination on the uptake of four deuterated PAH (PAH-d10) by spinach (Spinacia oleracea L.) in aged soil. PAH-associated health risks for soil, plant, and air exposure pathways were also assessed. The results showed that both individual Cu or warming decreased the PAH-d10 concentrations in root and shoot (non-normalized by lipid content) as well as the total PAH-associated cancer risk. Although antagonism existed between warming and Cu, compared to the presence of Cu, warming further reduced the spinach uptake of PAHs-d10 and total PAH-associated cancer risk, and the reductions were stronger at higher Cu levels. The inhibitory effect of the binary combination on PAH-d10 root uptake was attributed to decreased root lipid content and phytoavailable concentrations of PAHs-d10 in soil as a consequence of biodegradation, aging effect and cation-π interaction. The antagonism between warming and Cu on spinach uptake could be explained by their opposite effects on PAH-d10 biodegradation and the inhibition of the cation-π interaction caused by warming. Additionally, the shoot uptake of PAHs-d10 was mainly controlled by their soil to air to shoot partitioning. The findings suggest that the interactive effects of climate warming and co-existing pollutants should be taken into account for the assessment of plant uptake and health risk of PAHs.

Improved prediction of the bioconcentration factors of organic contaminants from soils into plant/crop roots by related physicochemical parameters

There has been an on-going pursuit for relations between the levels of chemicals in plants/crops and the source levels in soil or water in order to address impacts of toxic substances on human health and ecological quality. In this research, we applied the quasi-equilibrium partition model to analyze the relations for nonionic organic contaminants between plant/crop roots and external soil/water media. The model relates the in-situ root concentration factors of chemicals from external water into plant/crop roots (RCF(water)) with the system physicochemical parameters and the chemical quasi-equilibrium states with plant/crop roots (αpt, ≤1). With known RCF(water) values, root lipid contents (flip), and octanol-water Kow's, the chemical-plant αpt values and their ranges of variation at given flipKow could be calculated. Because of the inherent relation between αpt and flipKow, a highly distinct correlation emerges between log RCF(water) and log flipKow (R2 = 0.825; n = 368), with the supporting data drawn from 19 disparate soil-plant studies covering some 6 orders of magnitude in flipKow and 4 orders of magnitude in RCF(water). This correlation performs far better than any relationship previously developed for predicting the contamination levels of pesticides and toxic organic chemicals in plant/crop roots for assessing risks on food safety.

Uptake, translocation and biotransformation of N-ethyl perfluorooctanesulfonamide (N-EtFOSA) by hydroponically grown plants.

N-ethyl perfluorooctane sulfonamide (N-EtFOSA) is an important perfluorooctanesulfonate (PFOS) precursor (PreFOS) which is used in sulfluramid. The present work studied the uptake, translocation and metabolism of N-EtFOSA in wheat (Triticum aestivum L.), soybean (Glycine max L. Merrill) and pumpkin (Cucurbita maxima L.) by hydroponic exposure. Except for parent N-EtFOSA, its metabolites of perfluorooctane sulfonamide acetate (FOSAA), perfluorooctane sulfonamide (PFOSA), PFOS, perfluorohexane sulfonate (PFHxS) and perfluorobutane sulfonate (PFBS) were detected in the roots and shoots of all the three plant species examined. This suggested that plant roots could take up N-EtFOSA from solutions efficiently, and translocate to shoots. A positive correlation was found between root concentration factors (RCFs) of N-EtFOSA and root lipid content. Much higher proportion of N-EtFOSA transformation products in plant tissues than in the solutions suggested that N-EtFOSA could be invivo metabolized in plant roots and shoots to FOSAA, PFOSA and PFOS, and other additional shorter-chain perfluoroalkane sulfonates (PFSAs), including PFHxS and PFBS. The results suggested that plants had biotransformation pathways to N-EtFOSA that were different than those from microorganisms and animals. This study provides important information about the uptake and metabolism of PreFOSs in plants.

Capabilities of Seven Species of Aquatic Macrophytes for Phytoremediation of Pentachlorophenol Contaminated Sediment

Sediments are regarded as the ultimate sink of pentachlorophenol(PCP) in aquatic environment, and capabilities of seven species of aquatic macrophytes for remediating PCP contaminated sediment were investigated. Seven species of aquatic macrophytes could significantly accelerate the degradation of PCP in sediments. Among all, canna indica L., Acorus calamus L. and Iris tectorum Maxim. can be used as efficient alternative plants for remediation of PCP contaminated sediment, which attained 98%, 92% and 88% of PCP removal in sediments, respectively. PCP was detected only in root tissues and the uptake was closely related to the root lipid contents of seven plants. The presence of seven aquatic macrophytes significantly increased microbial populations and the activities of dehydrogenase compared with control sediments, indicating that rhizosphere microorganism played important role in the remediation process. In conclusion, seven species of aquatic macrophytes may act as promising tools for the PCP phytoremediation in aquatic environment, especially Canna indica L., Acorus calamus L. and Iris tectorum Maxim.

The roles of protein and lipid in the accumulation and distribution of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in plants grown in biosolids-amended soils

The roles of protein and lipid in the accumulation and distribution of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in seven species of plants from biosolids-amended soils were investigated. The PFOS and PFOA root concentration factors (Croot/Csoil) ranged from 1.37 to 4.68 and 1.69 to 10.3 (ng/groot)/(ng/gsoil), respectively, while the translocation factors (Cshoot/Croot) ranged from 0.055 to 0.16 and 0.093 to 1.8 (ng/gshoot)/(ng/groot), respectively. The PFOS and PFOA accumulations in roots correlated positively with root protein contents (P < 0.05), while negatively with root lipid contents (P < 0.05). These suggested the promotion effects of protein and inhibition effects of lipid on root uptake. The translocation factors correlated positively with the ratios between protein contents in shoots to those in roots (P < 0.05), showing the importance of protein on PFOS and PFOA translocation. This study is the first to reveal the different roles of protein and lipid in the accumulation and distribution of PFOS and PFOA in plants.

The Influence of Plants in the Remediation of Petroleum Hydrocarbon- Contaminated Sites

Petroleum hydrocarbon contamination is an environmental concern. Of the various hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) are a major worry because they cause many health problems including cancer and the inflammation of tissue in humans. So, it is necessary to remediate contaminated sites. Sites with diffuse low to medium level pollution can be remediated with the use of biological techniques, such as phytoremediation. Phytoremediation is a low input biotechnology approach: it relies on the knowledge that natural attenuation by biodegradation and physicochemical mechanisms will decrease the pollutant concentration. Limited PAH uptake by plant roots also takes place. This is influenced by both the organic content of the soil in which the plants are grown and the plant root lipid contents. Plant responses to growth in soils contaminated with petroleum hydrocarbons need to be taken into account, if plants are to be used to clean up petroleum hydrocarbon contamination. Different plant species show various stress responses and adaptations to survive the stress conditions caused by hydrocarbonpollution. The responses of plants also vary with the type and amount of the contaminant as well as duration of exposure. Phytoremediation can be feasible if appropriate plant species are selected. They must show sufficient morphological plasticity to survive stress situations induced by hydrocarbon-contamination, have an extended rhizosphere and appropriate root exudate patterns, positively influence the growth of hydrocarbon-degrading microorganisms in contaminated soil, and should also limit the uptake of toxic molecules through various adaptations to the root ultrastructure and cell wall components. Plants chosen should also be native to the area to be remediated so that they will be tolerant to the soil and environmental conditions. Additionally, plants that require little attention are preferable because cost is an important factor. Plants with deep, fibrous roots and fast growth, such as grasses, are generally considered useful in phytoremediation.

Transfer of wastewater associated pharmaceuticals and personal care products to crop plants from biosolids treated soil

The plant uptake of emerging organic contaminants such as pharmaceuticals and personal care products (PPCPs) is receiving increased attention. Biosolids from municipal wastewater treatment have been previously identified as a major source for PPCPs. Thus, plant uptake of PPCPs from biosolids applied soils needs to be understood. In the present study, the uptake of carbamazepine, diphenhydramine, and triclocarban by five vegetable crop plants was examined in a field experiment. At the time of harvest, three compounds were detected in all plants grown in biosolids-treated soils. Calculated root concentration factor (RCF) and shoot concentration factor (SCF) are the highest for carbamazepine followed by triclocarban and diphenhydramine. Positive correlation between RCF and root lipid content was observed for carbamazepine but not for diphenhydramine and triclocarban. The results demonstrate the ability of crop plants to accumulate PPCPs from contaminated soils. The plant uptake processes of PPCPs are likely affected by their physico-chemical properties, and their interaction with soil. The difference uptake behavior between plant species could not solely be attributed to the root lipid content.

Uptake of Galaxolide, Tonalide, and Triclosan by Carrot, Barley, and Meadow Fescue Plants

Many xenobiotics entering wastewater treatment plants are known to be persistent during wastewater treatment and tend to adsorb to sewage sludge. The application of sewage sludge as fertilizer in agriculture may pose the risk of an incorporation of xenobiotics in the cultivated plants and, finally, an inclusion into the food chain. This study was performed to investigate the uptake of common sewage sludge contaminants, galaxolide, tonalide, and triclosan, by plants used for human consumption and livestock feeding. Barley, meadow fescue, and four carrot cultivars were sown and grown in spiked soils under greenhouse conditions. After harvesting the plants, roots and leaves were analyzed separately, and the respective bioconcentration factors were calculated. In carrots, a concentration gradient of the xenobiotics became evident that decreased from the root peel via root core to the leaves. A significant influence of the differing root lipid contents on the uptake rates cannot be supported by our data, but the crucial influence of soil organic carbon content was confirmed. Barley and meadow fescue roots incorporated higher amounts of the target substances than carrots, but translocation into the leaves was negligible. The results indicated that an introduction of persistent semi- and nonpolar xenobiotics into the food chain via edible plants like carrots could be of certain relevance when sludge is applied as fertilizer. Due to low rates found for the translocation of the xenobiotics into the aerial plant parts, the entrance pathway into food products via feeding livestock is less probable.

Investigation of the mechanism of uptake and accumulation of zwitterionic tetracyclines by rice (Oryza sativa L.)

The uptake and accumulation of organic contaminants by plants can be detrimental to the plant itself as well as consumers. Tetracycline antibiotics are present at trace levels in soil and water. Under typical environmental conditions, they exist as zwitterions. Comparatively little is known of their uptake and accumulation by plants, or the mechanism by which this occurs. To examine this, rice (Oryza sativa L.) was employed, together with a static diffusion cell equipped with a cellulose membrane as a model for the uptake process. For rice, kinetic results suggested that the zwitterions were behaving similarly to neutral organic compounds, with a passive uptake process. The diffusion cell provided qualitatively similar results. When exposed to aqueous concentrations of zwitterionic tetracyclines of 50mgL−1 over 15 days, no translocation to shoots or detrimental effects on plants was observed. Despite relatively low root lipid contents, concentrations in root tissue of greater than 1000mgkg−1 (d.w.) were determined with maximum Root Concentration Factors of the order of 2000Lkg−1 (d.w.). Overall, for the tetracyclines investigated, kinetic and accumulation behavior in plants together with permeation in the diffusion cell were all governed by compound hydrophobicity.

Behavior of Decabromodiphenyl Ether (BDE-209) in the Soil−Plant System: Uptake, Translocation, and Metabolism in Plants and Dissipation in Soil

Deca-bromodiphenyl ether (BDE-209) is the major component of the commercial deca-BDE flame retardant. There is increasing concern over BDE-209 due to its increasing occurrence in the environment and in humans. In this study the behavior of BDE-209 in the soil-plant system was investigated. Accumulation of BDE-209 was observed in the roots and shoots of all the six plant species examined, namely ryegrass, alfalfa, pumpkin, summer squash, maize, and radish. Root uptake of BDE-209 was positively correlated with root lipid content (P < 0.001, R(2) = 0.81). The translocation factor (TF, C(shoot)/C(root)) of BDE-209 was inversely related to its concentration in roots. Nineteen lower brominated (di- to nona-) PBDEs were detected in the soil and plant samples and five hydroxylated congeners were detected in the plant samples, indicating debromination and hydroxylation of BDE-209 in the soil-plant system. Evidence of a relatively higher proportion of penta- through di-BDE congeners in plant tissues than in the soil indicates that there is further debromination of PBDEs within plants or low brominated PBDEs are more readily taken up by plants. A significant negative correlation between the residual BDE-209 concentration in soil and the soil microbial biomass measured as the total phospholipid fatty acids (PLFAs) (P < 0.05, R(2) = 0.74) suggests that microbial metabolism and degradation contribute to BDE-209 dissipation in soil. These results provide important information about the behavior of BDE-209 in the soil-plant system.

Adsorption and absorption of polycyclic aromatic hydrocarbons to rice roots

Rice roots and surrounding air, soil and water samples were collected for polycyclic aromatic hydrocarbon (PAH) analysis. The rice roots were separated into lateral roots and nodal roots, and the PAH concentration in the former was found to be higher than that in the latter. In addition, root physiological characteristics including root biotic mass, root lipid content and specific surface area are also discussed. When normalizing the total, adsorption and absorption PAH fractions on a dry root weight basis to root biomass, root lipid, and surface area bases respectively, the differences between PAHs in the two types of roots diminished by 2 to 3 times on average. Results from sequential extraction indicated that PAHs were more easily absorbed by interior rice roots than adsorbed on the surface. In addition, more than 60% of total PAHs accumulated in root tissue for both lateral and nodal roots. However, the results were highly related to the solvent used, extraction time and methodology. Correlation analysis between bioconcentration factors (root over environment) and K OA, K OW showed water to be more significant for PAH adsorption in rice roots than other environmental media.

Role of Arbuscular Mycorrhizal Fungi in Phytoremediation of Soil Rhizosphere Spiked with Poly Aromatic Hydrocarbons

Results from an innovative approach to improve remediation in the rhizosphere by encouraging healthy plant growth and thus enhancing microbial activity are reported. The effect of arbuscular mycorrhizal fungi (Am) on remediation efficacy of wheat, mungbean and eggplant grown in soil spiked with polyaromatic hydrocarbons (PAH) was assessed in a pot experiment. The results of this study showed that Am inoculation enhanced dissipation amount of PAHs in planted soil, plant uptake PAHs, dissipation amount of PAHs in planted versus unplanted spiked soil and loss of PAHs by the plant-promoted biodegradation. A number of parameters were monitored including plant shoot and root dry weight, plant tissue water content, plant chlorophyll, root lipid content, oxido-reductase enzyme activities in plant and soil rhizosphere and total microbial count in the rhizospheric soil. The observed physiological data indicate that plant growth and tolerance increased with Am, but reduced by PAH. This was reflected by levels of mycorrhizal root colonization which were higher for mungbean, moderate for wheat and low for eggplant. Levels of Am colonization increased on mungbean > wheat > eggplant. This is consistent with the efficacy of plant in dissipation of PAHs in spiked soil. Highly significant positive correlations were shown between of arbuscular formation in root segments (A)) and plant water content, root lipids, peroxidase, catalase polyphenol oxidase and total microbial count in soil rhizosphere as well as PAH dissipation in spiked soil. As consequence of the treatment with Am, the plants provide a greater sink for the contaminants since they are better able to survive and grow.

Application of the partition-limited model for plant uptake of organic chemicals from soil and water

This study further examined the merits of the partition-limited model for the plant uptake of organic chemicals from soil and water. The influential factors on the quasi-equilibrium factor ( α pt) of the model were evaluated for a number of systems. The present study manifested a generally high efficiency of the model for prediction of phenanthrene and pyrene uptake by plants. The overall model predictions are within an order of magnitude of the measured values, with the differences between the estimated and measured concentrations being less than 93.7% in most cases. Modeled root concentrations seemed to be more accurate than modeled shoot concentrations. Generally, the calculated α pt values for plant uptake of chemicals from water, including phenanthrene and pyrene on basis of our experimental data and lindane and trifluralin on basis of the available literature data, tend to be relatively constant after an initial fast increase with increasing uptake time. α pt values for root uptake of these chemicals are always greater than those for shoot uptake. In addition, α pt values for various root uptake of hydrophobic chemicals, e.g., phenanthrene and pyrene, exhibit significantly positive correlations with root lipid contents ( p<0.05, n=10). This investigation substantiated the concept of the partition-limited model and its utility for vegetation-uptake assessment.

Prediction of phenanthrene uptake by plants with a partition-limited model

The performance of a partition-limited model on prediction of phenanthrene uptake by a wide variety of plant species was evaluated using a greenhouse study. The model predictions of root or shoot concentrations for tested plant species were all within an order of magnitude of the observed values. Modeled root concentrations appeared to be more accurate than modeled shoot concentrations. The differences of simulated and experimented concentrations of phenanthrene in roots and shoots of three representative plant species, including ryegrass, flowering Chinese cabbage, and three-colored amaranth, were less than 81% for roots and 103% for shoots. Results are promising in that the α pt values of the partition-limited model for root uptake of phenanthrene correlate well with root lipid contents. Additionally, a significantly positive correlation is also observed between root concentration factors (RCFs, defined as the ratio of contaminant concentrations in root and in soil on a dry weight basis) of phenanthrene and root lipid contents. Results from this study suggest that the partition-limited model may have potential applications for predicting the plant PAH concentration in contaminated sites.

Prediction of phenanthrene uptake by plants with a partition-limited model

The performance of a partition-limited model on prediction of phenanthrene uptake by a wide variety of plant species was evaluated using a greenhouse study. The model predictions of root or shoot concentrations for tested plant species were all within an order of magnitude of the observed values. Modeled root concentrations appeared to be more accurate than modeled shoot concentrations. The differences of simulated and experimented concentrations of phenanthrene in roots and shoots of three representative plant species, including ryegrass, flowering Chinese cabbage, and three-colored amaranth, were less than 81% for roots and 103% for shoots. Results are promising in that the αpt values of the partition-limited model for root uptake of phenanthrene correlate well with root lipid contents. Additionally, a significantly positive correlation is also observed between root concentration factors (RCFs, defined as the ratio of contaminant concentrations in root and in soil on a dry weight basis) of phenanthrene and root lipid contents. Results from this study suggest that the partition-limited model may have potential applications for predicting the plant PAH concentration in contaminated sites.

Plant uptake, accumulation and translocation of phenanthrene and pyrene in soils

Uptake, accumulation and translocation of phenanthrene and pyrene by 12 plant species grown in various treated soils were comparatively investigated. Plant uptake and accumulation of phenanthrene and pyrene were correlated with their soil concentrations and plant compositions. Root or shoot accumulation of phenanthrene and pyrene in contaminated soils was elevated with the increase of their soil concentrations. Significantly positive correlations were shown between root concentrations or root concentration factors (RCFs) of phenanthrene and pyrene and root lipid contents. The RCFs of phenanthrene and pyrene for plants grown in contaminated soils with initial phenanthrene concentration of 133 mg kg −1 and pyrene of 172 mg kg −1 were 0.05–0.67 and 0.23–4.44, whereas the shoot concentration factors of these compounds were 0.006–0.12 and 0.004–0.12, respectively. For the same soil–plant treatment, shoot concentrations and concentration factors of phenanthrene and pyrene were generally much lower than root. Translocations of phenanthrene and pyrene from shoots to roots were undetectable. However, transport of these compounds from roots to shoots usually was the major pathway of shoot accumulation. Plant off-take of phenanthrene and pyrene only accounted for less than 0.01% of dissipation enhancement for phenanthrene and 0.24% for pyrene in planted versus unplanted control soils, whereas plant-promoted biodegradation was the predominant contribution of remediation enhancement of soil phenanthrene and pyrene in the presence of vegetation.

Effects of Seed and Root Lipids on the Susceptibility of Plants to Trifluralin and Oryzalin

Extensive variability in total lipid composition was observed in seeds of different plant species as well as cultivars within the same species. Susceptibility of plants to soil-incorporated trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) and oryzalin (3,5-dinitro-N4,N4-dipropyisulfanilamide) under greenhouse conditions decreased as the percentage of total lipid in dry seeds increased. Species with high seed lipid levels such as jimsonweed (Datura stramoniumL.), soybean [Glycine max(L.) Merr.], and velvetleaf (Abutilon theophrastiMedic.) were less susceptible to these herbicides than were oat [Avena sativa(L.), giant foxtail (Setaria faberiHerrm.), and sorghum [Sorghum bicolor(L.) Moench.] with low seed lipid levels. Velvetleaf was the most tolerant to the herbicides. Corn (Zea maysL.) cultivars with a wide range of seed lipid content (4.45 to 17.0% of dry weight) were germinated in herbicide-free soil, but their roots were allowed to grow through trifluralin- or oryzalin-treated soil. Roots of seedlings from seeds with high lipid content had higher lipid contents than those from low-lipid seeds. There was a significant correlation between root lipid content and sensitivity to trifluralin or oryzalin. Roots high in lipids were less susceptible than those with low amounts of lipids. Similar results were obtained for oat cultivars. The fatty acid composition of plant roots differed among plant species and also among cultivars of the same species. The individual fatty acids did not significantly correlate with susceptibility of roots to trifluralin or oryzalin. Root lipid and fatty acid compositions were not significantly altered by trifluralin or oryzalin treatment.