Possible Independent Variables

  • air movement (wind speeds, wind direction)
  • atmospheric carbon dioxide (low to high concentrations)
  • atmospheric humidity (low to high humidity)
  • atmospheric pollution (fresh air to polluted air)
  • chemical concentration (low to high concentration)
  • chemicals (none vs. household chemicals)
  • competition (no competition, interspecific, intraspecific)
  • environment (laboratory, yard, field)
  • hormone concentration (low to high)
  • hormone (auxins, gibberellins, cytokinins)
  • insects (presence, absence, density of insects)
  • light angle (overhead, oblique, angle)
  • light color (red, orange, yellow, green, blue, violet)
  • light intensity (absence or presence; high to low intensity)
  • light quality (incandescent, fluorescent, natural)
  • nutrient application (foliar, systemic)
  • nutrients (N, P, K concentrations)
  • nutrients (natural, synthetic, manufacturer)
  • pesticide application (foliar, water, injection)
  • pesticide concentration (low to high)
  • pesticide type (insecticides, snail killers, fungicides)
  • planting density (one to many per pot)
  • salinity (fresh vs. saline, low to high, sodium chloride vs. other salts)
  • soil bio-matter (debris from conifers, broad leaf trees, or grasses)
  • soil classification (alfisols, andisols, aridisols, entisols)
  • soil pH (alkaline, neutral, acidic)
  • soil profile (humus, top soil, elluviation, subsoil, regolith, bedrock)
  • soil source (field, stream bank, mountain side, sediment)
  • soil type (sand, clay, silt, loam)
  • temperature (high to low, boiling, freezing)
  • temperature treatments (duration, regimen)
  • water application (foliar, basin, subsurface)
  • water pH (acidic, basic, neutral, pH 0-14)
  • water pollution (household chemicals, acid, base)
  • water source (tap, distilled, bottled, stream, lake, ocean