Bucior, Erika , Melcher, Peter .
The physiological responses of Brassica rapa (Fast Plants) to nutrient and drought stress.
The rapid six-week life cycle of Brassica rapa (Fast plantsTM) makes them a useful plant for laboratory studies and are used in high schools and colleges across the globe. This study was motivated by the fact that there are no studies in the peer-reviewed literature aimed at understanding the physiological responses of this species to drought and nutrient stress. We subjected plants to four treatment combinations: well watered (WW) and low nutrient (LN); low water (LW) and high nutrient (HN); LW and LN; and WW and HN. We developed a water-wick delivery system that maintained constant levels of desired soil water potentials for the duration of the experiments. For each treatment, we measured root and shoot biomass allocation, long-term water use efficiency (WUE) from carbon isotope analysis, % nitrogen and carbon; carbon assimilate rates, from photosynthetic light response curves, and PSII electron transport efficiency (ETE) using a fluorescence imaging system. As hypothesized, we found that LWxLN had higher root to shoot biomass allocation compared to all other treatments (ANOVA F=12.4; P>0.0001). Nutrient and water stress alone had decreased ETE rates compared to HWHN treatments (Mann-Whitney, P=0.03,). HWxHN had significantly higher ETE compared to all other treatments, and plants grown in the LWxLN treatments showed significantly lower ETE rates than all other treatments (ANOVA F=9.63; P=0.002; n=4). However, ETE data showed no significant differences for plants grown under HWxLN and LWxHN treatments (Mann-Whitney P=0.67). We also found that WUE was not significantly different across all treatments. However, C:N ratios increased with decreasing water and nitrogen availability as a result of changes in %Nitrogen as expected (ANOVA F=5.5; P=0.015). This study clearly shows that B. rapa is plastic in response to changes in water and nutrient levels but when both of these abiotic factors are limited, we observed the largest changes in both physiological responses and plant growth and habit. Further work is needed to determine the effects of water stress and nutrients on plant yield and also the responses of this species to changes in light environments.
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1 - Ithaca College, Dept. of Environmental Studies & Sciences, 953 Danby Rd, Ithaca, NY, 14850, USA
2 - Ithaca College, Center For Natural Sciences, Ithaca, NY, 14850, USA
Presentation Type: Poster:Posters for Sections
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Candidate for Awards:Physiological Section Best poster presentation,Physiological Section Physiological Section Li-COR Prize