Petroleum-based spills on turfgrass often occur during lawn care maintenance. The damages caused by hydrocarbons to turfgrass can be long lasting and difficult to correct because of the stable and toxic nature of hydrocarbons. The objective of this study was to compare the effectiveness of using detergent, nitrate nutrient, humic substance, and activated charcoal to enhance bioremediation and turf recover after gasoline, diesel, and hydraulic fluid spills. The turfgrass quality and reestablishment of perennial ryegrass (Lolium perenne) reseeded at 0, 1, and 2 weeks after spills were evaluated. The results showed that using a liquid humic substance to remediate soil and reseed immediately after a gasoline spill was a practical method to reestablish acceptable turfgrass quality in 5 weeks. The most significant injury to perennial ryegrass caused by gasoline was bleaching of green tissues. Gasoline caused negligible residual herbicidal effects under the remediation regime in this study. However, diesel or hydraulic fluid showed phytotoxicity and residual effects in the contaminated soil for more than 2 months. Seeds applied immediately after diesel and hydraulic fluid spills lost viability as a result of the herbicidal effect of these hydrocarbons. As a result, reseeding was only successful 4 months after diesel and hydraulic fluid spills. Therefore, the time span for reestablishing perennial ryegrass turf may be too long for practical purposes in the lawn care industry.
Salvia miltiorrhiza, known as danshen, is one of most valued medicinal plants in China. Although it has been cultivated since ancient times, an optimal culture system needs to be standardized for this important species. Here, we explored the phytochemical properties of S. miltiorrhiza with the treatments of rare earth elements (REEs) to develop an optimal tissue culture system. Four-week-old in vitro-grown S. miltiorrhiza plantlets were used as explants. The experiment was conducted in a randomized block design on a Murashige and Skoog (MS) medium containing 0.2 mg·L−1 naphthaleneacetic acid (NAA) to induce rooting at four different concentrations (50, 100, 200, and 300 μM) of REEs such as cerium (Ce), lanthanum (La), or praseodymium (Pr), respectively. Compared with all REEs at different concentrations, 100 μM Pr induced greater root length than Ce or La at any concentrations. Concomitantly, 0.38 μg tanshinone IIA/mg dry weight (DW) was observed, which was 54.84% higher than in the control. Similarly, chlorophyll content, antioxidant enzyme activity, and secondary metabolite were enhanced in rooting medium supplemented with 100 μM Pr. Therefore, this study showed that 100 μM Pr is an adequate concentration in the optimal culture system for promoting plant growth as well as enhancing secondary metabolite content in S. miltiorrhiza.