Lecture 21 Flashcards
what is the definition of plant nutrition
uptake from environment of all required raw material, distribution of materials within the plant, use of materials in metabolism and growth
what makes an element essential
needed for plant to complete its life cycle, part of any molecule/constituent that is essential to plant, deficiency symptoms appear if element is absent
what are the many roles of essential elements
structural, enzymatic, regulatory, and ionic
what are some nutrient deficiency symptoms
most associated with shoot, necrosis, chlorosis, phloem-mobile elements
what is necrosis
localized tissue death
what is chlorosis
loss or reduced chlorophyll
what is phloem-mobile elements
(Mg, P, K, N) show up in old leaves vs. immobile elements (Fe and Ca) show up in new leaves
what does the soil provide the plant with
support, inorganic nutrients, water, suitable gaseous environment for roots
what are the soil horizons
A horizon (topsoil), B horizon, C horizon, and bedrock
what are soil horizons
vary by amount of living and dead organic matter, and porosity, structure, and the extent of weather of bedrock
what is water potential
measured as pressure units in soil, plant, and air; indication of amount of water held in soil; below minimum threshold, plant will wilt
what are nutrient cycles
biogeochemical cycles; 17 essential elements for plants; dependent on recycling of nutrients; may be global or localized
what are the three main processes of nutrient cycling
ammonification, nitrification, assimilation
what is ammonification
plants can take up ammonium
what is nitrification
plants take up nitrate
what are some losses of nitrogen from soil
harvest and removal of plants, soil erosion, burning plants, leaching
why is nitrogen fixation important
all living organisms depend on this process, just as they depend on photosynthesis for their energy
what is assimilation
evidence that many plants take up organic compounds directly
what are two things that impact the nutrient cycles and effects pollution
human population growth and acid rain
why is plant nutrition research important
to overcome soil deficiencies and toxicities
how is plant nutrition research being done
select and develop varieties of plants rather than amending soil; phytoremediation; manipulate biological N fixation
what is the phosphorus cycle
in the curst, localized cycling, amount of P required by plants small compared with N, P has low solubility and mobility, is often the limiting nutrient
