. essential chemical elements absorbed from the soil in the form of inorganic icons.
: plants need nitrogen, which they acquire from the soil mainly in the form of
. 80% of herbaceous plant is water, and plants grow mainly by accumulating water in the
. water is considered a nutrient because it supplies hydrogen atoms and some oxygen
atoms that are incorporated into organic compounds by photosynthesis
more than 90% of the water absorbed is lost by transpiration
most of the water retained by the plant functions as a solvent, provides most of
the mass for cell elongation helps maintain the form off the soft tissue by keeping
the cells turgid
. CO2 from the atmosphere is the main component of the bulk of organic material
Water content can be measured by comparing the weight of the plant material before and
after it is dried. The chemical composition of the residue can be analyzed.
. organic substances account for 95% of the dry weight
. inorganic substances making up 5%
. carbon, oxygen, hydrogen (carbohydrates) are most abundant elements in dry
weight of the plant
. some organic molecules contain nitrogen, sulfur, or phosphorus
it is required for a plant to grow from a seed and complete the lifecycle
. hydroponic culture helps determine which of the minerals are essential nutrients
nine macronutrients in total that plants need in large sums. The six major
ingredients of organic compounds: carbon, oxygen, hydrogen, nitrogen, sulfur and
phosphorus. The other three are potassium, calcium, and magnesium
iron, chlorine, copper, manganese, zing, molybdenum, boron, nickel.
these function mainly as cofactors of enzymatic reactions.
Ex: iron is a metallic component of cytochromes (ETC)
because micronutrients only play catalytic roles, they are only needed in small
amounts, however deficiencies may weaken or kill the plant.
Mineral deficiencies depend not only on the role of the nutrient, but also its mobility
within the plant.
. young, growing tissues have ‘drawing power’ than old tissues for nutrients, and thus
deficiencies show up first in the older organs
preferential routing is the source-to-sink translocation in phloem
. a deficiency of a nutrient that is relatively immobile within a plant will affect young
parts of the plant first.
. older tissues may have adequate supply of the mineral, which they are able to retain
during periods of short supply
Ex: iron does not move freely within a plant, and a deficiency of iron will cause
yellowing of young leaves before any effect on older leaves is visible.
.shortages of micronutrients are less common and tend to be geographically localzed
because of differences in soile composition