plant nutrition

• Nutrients


  • Carbohydrates
  • Fats
  • Proteins
  • Vitamins
  • Minerals
• Nutrition


  The mode of taking food by an organism and its utilization in the body
• Modes of nutrition


  • Autotrophic nutrition
  • Heterotrophic nutrition
• Autotrophic nutrition


  Nutrition in which organisms can prepare their own food
• Heterotrophic nutrition


  Nutrition in which organisms get their food directly or indirectly from plants
• Photosynthesis


  1. Sunlight obtained from the sun

  2. Water absorbed by roots and transported to leaves

  3. Carbon dioxide taken from air through stomata

  4. Chlorophyll uses energy from sunlight to prepare carbohydrate from water and carbon dioxide, releasing oxygen
• Equation of photosynthesis: Sunlight + Carbon dioxide + Water —> Carbohydrate + Oxygen
• Synthesis of proteins


  1. Bacteria convert nitrogen from air into usable nitrogen in soil

  2. Plants absorb nitrogen from soil along with water and other constituents to prepare proteins and fats
• Other modes of nutrition in plants

  • Parasitic plants - get their food from hosts
  • Insectivorous plants - feed on insects
  • Saprotrophs - get their food from dead and decaying organic matter
• Parasitic plants


  • Cuscuta (Amarbel)
• Pitcher plant


  • Leaf modified into a pitcher
  • End of pitcher has a lid which can open and close
  • When an insect enters, the lid closes and the insect is digested by digestive juices
• Saprotrophs


  • Mushroom, bread mould
• How nutrients are replenished in the soil

  • Plants absorb nutrients from soil, so farmers add manures and fertilisers to increase nutrients
  • Rhizobium bacteria convert nitrogen from air into soluble form in soil, making it rich in nitrogen, in return the plant provides food and shelter to the bacteria
• Autotrophic plant needs


  • Sun as energy source
  • Inorganic compounds as raw materials (water, CO2, minerals)
• Macronutrients


  • Carbon, Oxygen, Hydrogen, Nitrogen, Phosphorus, Potassium, Calcium, Magnesium, Sulfur
• Micronutrients


  • Chlorine, Iron, Manganese, Boron, Zinc, Nickel, Copper, Molybdenum
• Nutrient deficiencies


  Lack of essential nutrients, dependent on function of nutrient and solubility of nutrient
• Magnesium deficiency symptoms


  Chlorosis (yellowing of leaves), plant moves Mg+ to newer leaves
• Factors affecting plant growth

  • Soil texture/structure
  • Soil composition (organic & inorganic chemical components, fertility)
• Importance of organic matter

  • Topsoil is most important for plant growth and is rich in organic matter
  • Humus is decomposing organic material that improves soil texture and is a reservoir of minerals
  • Soil has many living organisms like bacteria, fungi, algae, protists, insects, earthworms, nematodes
• Not taking care of soil health has far-reaching, damaging consequences like the Dust Bowl in the 1920s
• Sustainable agriculture involves maintaining a healthy environment, sustainable food production, and an economically viable farming industry
• Global soil issues


  • Soil fertility
  • Erosion
  • Irrigation
  • Forestry destruction
• Fertilizers


  • Organic (manure, compost, fishmeal)
  • Chemical (commercially manufactured, Nitrogen-Phosphorus-K (Potatissium))
• Nitrogen uptake


  1. Plants can only take up nitrate (NO3-)

  2. Nitrogen cycle by bacteria
• Soybean root nodules contain Rhizobium bacteria that fix nitrogen in a symbiotic relationship
• Cover crops


  Growing a field of plants just to plow them under, usually a legume crop, to put nitrogen back in the soil and take care of soil's health
• Parasitic plants


  Tap into host plant's vascular system
• Parasitic plants


  • Indian Pipe, Mistletoe
• Plants of peat bogs

  High acid environment, most minerals & nutrients bound up and not available to plants, must find alternative sources of nutrients
• Carnivorous plants


  Attract, trap and digest animals for the nutrients they contain
• Carnivorous plants


  • Venus fly trap, Pitcher plant, Sundew
• Specialized absorptive structures in plants

  • Root hairs
  • Root nodules
  • Mycorrhizae
• Root hairs


  Slender extensions of specialized epidermal cells that greatly increase the surface area available for absorption
• Root nodules


  Localized swellings in roots of certain plants where bacterial cells exist symbiotically with the plant, helping the plant fix nitrogen
• Mycorrhizae


  Symbiotic interaction between a young root and a fungus, the fungus obtains sugars and nitrogen-containing compounds from root cells while the plant gets some scarce minerals the fungus can better absorb
• Routes for absorption of water and minerals across plant roots

  • Symplast route (through plasmodesmata)
  • Apoplast route (along cell walls)
• Plant parasites


  Parasitic plants depend on their host for survival, obtaining water and nutrients through connections to the host's vascular system
• Plant parasites


  • Dodder
• Holoparasites


  Completely dependent on their host