Assessing the Effect of Diesel Fuel on the Seed Viability and Germination of Medicago sativa Using the Event-Time Model

Abstract

The remediation of contaminated sites using plant-based techniques has gained increasing attention in recent decades. However, information on the effects of contaminant imbibition on seed viability and germination rates are often lacking in the literature. To this end, our research investigated, by means of an event-time model, the effect of diesel fuel imbibition on the seed viability and germination rate of Medicago sativa, a plant species with great potential for remediation of organic contaminants. The event-time model provided an accurate and biologically relevant method for analysing germination data. Our results reveal that the direct imbibition of diesel fuel by M. sativa seeds for ≤48 h, or their exposure to soil diesel fuel concentrations of 0–10 g/kg diesel fuel, affects their germination rates, as shown by increasing t50 values from 90.6 (±2.78) to 114.2 (±2.67) hours, without significantly affecting seed viability. On the other hand, diesel fuel imbibition of longer duration, or the exposure of M. sativa seeds to ≥20 g/kg diesel fuel-contaminated soils, leads to no further effect on time to seed emergence. Instead, these conditions compromise seed viability, resulting in a decrease in the proportion of germinated seeds from 0.91 (±0.03) in 10 g/kg diesel fuel contaminated soil to 0.84 (±0.04) and 0.70 (±0.05) in 20 and 30 g/kg diesel fuel-contaminated soils, respectively. The fact that low concentrations of diesel fuel and 0–48 h of direct imbibition delayed seed emergence without adversely affecting the percentage of viable seeds suggests that this inhibitory effect on germination at low diesel fuel exposure could be attributed more to physical constraints rather than biological damage on the seeds. The models used in this study provide an accurate and biologically relevant method for the analyses of germination data. This is vital since expensive germination experiments, be it in the field of toxicology or agriculture, deserve to be accurately analysed.

Elucidating the significant roles of root exudates in organic pollutant biotransformation within the rhizosphere

“…In this study, Medicago sativa L. did not exhibit any visual sign of diesel fuel toxicity. This agrees with our previous study that revealed that although diesel fuel may lead to a lag in germination, it does not significantly affect M. sativa seed viability and growth rate 18 . On the contrary, low concentrations of hydrocarbons tend to exert a stimulatory influence on M. sativa , a concept known as hormesis 15 , 31 , 32 .…”

“…The triphenyltetrazolium chloride (TTC) test has been developed to provide a rapid estimate of seed viability 16 – 18 . TTC is a clear, water-soluble compound (a salt) which is reduced by respiring tissues to yield triphenylformazan (TPF), a water-insoluble red pigment.…”

Biostimulation of Petroleum-Contaminated Soil Using Organic and Inorganic Amendments

“…Population growth, accompanied with an increasing need for energy, has led to the continuous exploration and extraction of crude oil [ 1 ]. Over the years, the increased crude oil output has had a severe unintended impact on aquatic [ 2 , 3 ] and terrestrial lives [ 4 , 5 ]. Crude oil is emitted into the environment in a variety of ways during drilling, transportation, and distribution [ 6 , 7 ].…”

Importance of Compost, Bentonite, and Calcium Oxide in Reducing Trace Element Content in Maize on Agricultural Soil Contaminated with Diesel Oil

“…Their effectiveness is limited by the depth of plant root penetration and contaminant availability [43,44], whereas the plant species used may disturb the biodiversity of the remediated area [43]. Implementation of the phytoremediation techniques on soils contaminated with DO may be hampered by other serious obstacles, i.e., the increased phytotoxicity of the soils and the detrimental effects of DO on seed viability and germination rates of remediation plants [45,46]. As a result, practical application of this remediation method becomes very difficult [46].…”

“…Implementation of the phytoremediation techniques on soils contaminated with DO may be hampered by other serious obstacles, i.e., the increased phytotoxicity of the soils and the detrimental effects of DO on seed viability and germination rates of remediation plants [45,46]. As a result, practical application of this remediation method becomes very difficult [46].…”