Plant response to water stress can be modified by the rhizosphere microbial community, but the range of responses across plant genotypes is unclear. We imposed drought conditions on 116 Festuca arundinacea (tall fescue) accessions using a rainout shelter for 46 days, followed by irrigation, to stimulate drought recovery in 24 days. We hypothesized that prolonged water deficit results in a range of phenotypic diversity (i.e., green color index) across tall fescue genotypes that are associated with distinct microbial taxonomic and functional traits impacting plant drought tolerance. Microbial extracellular enzyme activities of chitinase and phenol oxidase (targeting chitin and lignin) increased in rhizospheres of the 20 most drought tolerant genotypes. Lower rates of fungal (dark septate) endophyte root infection were found in roots of the most drought tolerant genotypes. Bacterial 16S rRNA gene and fungal ITS sequencing showed shifts in microbial communities across water deficit conditions prior to drought, during drought, and at drought recovery, but was not patterned by drought tolerance levels of the plant host. The results suggest that taxonomic information from bacterial 16S rRNA gene and fungal ITS sequences provided little indication of microbial composition impacting drought tolerance of the host plant, but instead, microbial extracellular enzyme activities and root fungal infection results revealed patterned responses from drought.

Fertilizers and pesticides applied to home lawns can contaminate surface and groundwater making them unfit for aquatic organisms and human consumption. Application of fertilizers and pesticides can improve the aesthetics of a home lawn, improve turfgrass shoot and root density, water use, organic matter accumulation, and other factors known to be influential in urban hydrology. A field study determined the impact of applying home landscape pesticides with or without supplemental irrigation of leaching into groundwater or runoff to surface water. Free-draining lysimeters having a sandy loam soil (coarse-loamy, mixed, active, mesic Lamellic Hapludalf) were used to monitor total volume and nutrients and pesticides losses. Samples from natural precipitation events were analysed for pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2, 6-dinitrobenzenamine] applied in spring, mecoprop [2-(4-Chloro-2-methylphenoxy) propionic acid]+2, 4-D (2,4-dichlorophenoxyacetic acid) applied both in late spring and early fall, and bifenthrin [(2-methyl-1,1-biphenyl-3-y1)-methyl-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethyl cyclopropanecarboxylate] applied in late summer. Pesticide concentrations fluctuated over time, but no differences in concentrations were observed from irrigated or non-irrigated turfgrass for any pesticide. Mecoprop and 2,4-D were the most mobile and values found in runoff during establishment were above maximum contaminant levels (MCL) for U.S. standards. Surface runoff of lawn pesticides were observed at concentrations several magnitudes higher than leachate. The total extent of pesticide runoff was 0.71%, 1.3%, 6.0%, and 0.003% of the amount applied for 2,4-D, mecoprop, pendimethalin and bifenthrin, respectively. With the exception of one sampling period, pendimethalin concentrations in runoff and leachate were low; however, when applied during a period of minimal turf growth and high precipitation, pendimethalin could contribute significantly to surface water pollution.