|Rhizobium & Legume Lab!
Plant: Red Clover (Trifolium pretense) – a type of legume plant
Bacterium: Genus Rhizobium (mixture of species)
It’s a symbiotic relationship between the clover & Rhizobium bacteria. The bacteria are naturally present in the soil, and when they find the clover plants, they form a commensalistic relationship with the clover. The bacteria live in nodules on the roots of the plant, drawing the atmospheric nitrogen from the pore spaces in the soil.
The bacteria naturally pull extra nitrogen from the atmosphere and provide it directly to the roots of the plant. This is Nitrogen Fixation and Nitrification, parts of the Nitrogen Cycle.
Trifolium pretense seeds (use ~10 seeds per pot, spread out in the vermiculite, covered with ~1 cm vermiculite)
Rhizobium bacteria in powder form
4-inch plastic pots w/ drain holes
Vermiculite (potting medium)
Tap water for watering plants
Custom-made nutrient solution (all macro- and micro-nutrients except N)
Duration of experiment: 6-7 weeks.
Germination will take ~1 week. We will gently water the seeds when the vermiculite is dry to the touch (every day or so) being careful not to physically disturb the surface. We will cover them to keep sunlight out (to minimize evaporation). Once the seeds germinate, we will uncover them and water them in the following manner: water them gently until water drains from the bottom of the pots, then add 100mL of nutrient solution. After ~1 week of plant growth post-germination, we will remove the weakest plants, leaving the two strongest plants to grow for the duration of the experiment.
What will be your:
Ideas: Amount of Rhizobium, method of seed inoculation, position of Rhizobium in vermiculite, etc.
Ideas: height of plant, biomass (dry weight) of whole plant, biomass of roots only, fresh weight of whole plant, fresh weight of roots only, # of nodules, # of leaves, total surface area of leaves, total root length, average root length, etc.
CONTROL GROUP (1 pot):
EXPERIMENTAL GROUP (2-3 pots):