Plant and Animal Nutrition

• nutrient - refers to any substance required for the growth and maintenance of an organism
• two types of organisms based on the mode of nutrition:

  1. autotrophs
  2. heterotrophs
• autotrophs - organisms that obtain energy from sunlight and chemicals to produce their own food
• heterotrophs - organisms that cannot make their own food and obtain their energy from other organism
• macronutrients - are those nutrients needed by all plants in relatively large amounts
• macronutrients:

  1. nitrogen
  2. phosphorus
  3. potassium
  4. sulphur
  5. magnesium
  6. calcium
• nitrogen - usually absorbed in the form of nitrate
• nitrogen - needed for proper leaf growth and development
• nitrogen - deficiency may produce yellowing of older leaves
• nitrogen - excess produces hypertrophy of foliage and suppresses fruit production
• potassium - important for maintaining the membrane potential of plant cells(turgidity)
• potassium - deficiency produces general symptoms of poor health, which can include localized chlorosis(low chlorophyll)
• phosphorus - essential for the production of such vital compounds as the nucleic acids and ATP
• phosphorus - needed for flowering, fruiting, and root development
• phosphorus - deficiency results in small dark green leaves over the entire plant
• sulfur - essential component of protein because of its occurrence in the amino acids cysteine and methionine
• sulfur - Deficiency produces chlorosis in new leaves and buds
• sulfur - cannot be absorbed in elemental form but must be present as sulfate
• calcium - important component of the middle lamella of cell walls
• calcium - deficiency results in abnormal growth and cell division
• magnesium - required for the action of many enzymes and is needed also in the synthesis of chlorophyll
• magnesium - deficiency, therefore, produces mottled chlorosis
• iron - needed in several of the electron transport substances of the cell (ferredoxin, cytochromes)
• iron - can occur in soils with high or low pH
• micronutrients - vitamins and minerals that are needed in small amounts
• micronutrients:

  1. boron
  2. copper
  3. iron
  4. chloride
  5. manganese
  6. molybdenum
  7. zinc
• boron - deficiency results in abnormally dark foliage, growth abnormalities, and malformations
• zinc- required for the production of amino acid tryptophan
• zinc - indirectly required for the production of auxins
• zinc - Deficiency produces small leaves and stunted stems owing to short internodes.
• zinc - poisonous to plants
• manganese - required as a cofactor for enzymes in oxidative metabolism and in photosynthetic oxygen production.
• manganese - Its deficiency produces a mottled, characteristic form of chlorotic leaf yellowing.
• chlorine - required for ionic balance and maintenance of cellular membrane potentials
• chlorine - its deficiency results in very small leaves and slow growth. Leaves become wilted, chlorotic, or even necrotic and may eventually become bronze-colored.
• molybdenum - needed as part of the denitrifying and nitrogen-fixing enzymes of microorganisms
• copper - component of some enzymes and cytochromes.
• copper - deficiency results in a lowered rate of protein synthesis and sometimes in chlorosis
• specialized absorptive structures:

  1. root hairs
  2. root nodules
  3. mycorrhizae
• root hairs – slender extensions of specialized epidermal cells that greatly increase the surface area available for absorption.