Effect of Plant Age on PCB Accumulation by Cucurbita pepo ssp. pepo

Abstract

A greenhouse experiment was conducted to investigate polychlorinated biphenyl (PCB) uptake and translocation from soil over time in pumpkin plants (Cucurbita pepo ssp. pepo cv. Howden). Plants were grown in weathered soil collected from a former industrial site contaminated with Aroclor 1248 (mean [PCB](soil) = 6.5 mg kg(-1)). Plants were harvested five times over 42 d and analyzed for total PCB concentration in the root and shoot tissues. The concentration of PCBs in the root was not significantly different between harvests (mean [PCB](root) = 21.5 mg kg(-1)). The concentration of PCBs in the shoots was also relatively stable over time (mean [PCB](shoot) = 3.5 mg kg(-1)) despite increases in shoot biomass (fresh weight of 4.3 g at Day 12 to 59 g at Day 42). This suggests that PCBs were continuously accumulated throughout the growth period. The trends found in this study indicate the optimal time to harvest C. pepo ssp pepo plants to maximize PCB phytoextraction is when the plant shoot has reached its maximum biomass.

Effect of pumpkin root exudates on ex situ polychlorinated biphenyl (PCB) phytoextraction by pumpkin and weed species

“…Pumpkin shoot BAFs were 0.97±1.6 and 1.2±0.09 for the control and root exudate groups, respectively (Online Resource 1, Table S1). Shoot BAFs from both groups for pumpkins and weeds were among the highest recorded PCB shoot BAFs to date for whole plant shoot tissues (Ficko et al 2010;Low et al 2009;White et al 2006;Whitfield Åslund et al 2007Whitfield Åslund et al , 2008Zeeb et al 2006).…”

“…Research at the Royal Military College of Canada and elsewhere has demonstrated that certain cultivars of Cucurbita pepo ssp. pepo (e.g., Howden pumpkins) are capable of accumulating highly hydrophobic contaminants such as polychlorinated biphenyls (PCBs) in plant root and shoot tissues (Low et al 2009;Whitfield Åslund et al 2007;Zeeb et al 2006). More recently, Ficko et al (2010) demonstrated that a variety of weed species can also accumulate PCBs in root and shoot tissues.…”

“…Due to the heterogeneity of PCBs in naturally weathered soil, the soil was thoroughly homogenized as described in Low et al (2009). Nine Rubbermaid® containers (measuring 33×23×10 cm) were then filled with soil.…”

“…pepo plants were selected to produce root exudates for this greenhouse study based on their documented ability to extract various organic contaminants from soil and translocate them into the shoot tissues (Hülster and Marschner 1995;Lunney et al 2004;Mattina et al 2004;White 2001;White et al 2006). The variety "Howden pumpkin" (hereafter referred to as pumpkin) was chosen for these experiments due to previous success in phytoextraction studies of PCBs (Low et al 2009;Whitfield Åslund et al 2007;Zeeb et al 2006). Seeds were purchased from the Ontario Seed Company Ltd. in Waterloo, Ontario.…”

Advances and perspective in bioremediation of polychlorinated biphenyl-contaminated soils

“…capotata L. ), pumpkin ( Cucurbita pepo ss pepo cv. Howden), carrots ( Daucus carota L. ), squash ( C. pepo ssp ovifera ), zucchini ( C. pepo ssp pepo ), beets ( Beta vulgaris ), turnips ( Barssica rapa L. ) and beans ( Phaseolus vulgaris ) (Iwata and Gunther 1976; Fries and Marrow 1981; Webber et al 1994; White et al 2006; Low et al 2010). For the same reason, they are taken up by plant tissues in negligible amounts.…”