Lecture 21

Question 1

what is the definition of plant nutrition

Answer 1

uptake from environment of all required raw material, distribution of materials within the plant, use of materials in metabolism and growth

Question 2

what makes an element essential

Answer 2

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

Question 3

what are the many roles of essential elements

Answer 3

structural, enzymatic, regulatory, and ionic

Question 4

what are some nutrient deficiency symptoms

Answer 4

most associated with shoot, necrosis, chlorosis, phloem-mobile elements

Question 5

what is necrosis

Answer 5

localized tissue death

Question 6

what is chlorosis

Answer 6

loss or reduced chlorophyll

Question 7

what is phloem-mobile elements

Answer 7

(Mg, P, K, N) show up in old leaves vs. immobile elements (Fe and Ca) show up in new leaves

Question 8

what does the soil provide the plant with

Answer 8

support, inorganic nutrients, water, suitable gaseous environment for roots

Question 9

what are the soil horizons

Answer 9

A horizon (topsoil), B horizon, C horizon, and bedrock

Question 10

what are soil horizons

Answer 10

vary by amount of living and dead organic matter, and porosity, structure, and the extent of weather of bedrock

Question 11

what is water potential

Answer 11

measured as pressure units in soil, plant, and air; indication of amount of water held in soil; below minimum threshold, plant will wilt

Question 12

what are nutrient cycles

Answer 12

biogeochemical cycles; 17 essential elements for plants; dependent on recycling of nutrients; may be global or localized

Question 13

what are the three main processes of nutrient cycling

Answer 13

ammonification, nitrification, assimilation

Question 14

what is ammonification

Answer 14

plants can take up ammonium

Question 15

what is nitrification

Answer 15

plants take up nitrate

Question 16

what are some losses of nitrogen from soil

Answer 16

harvest and removal of plants, soil erosion, burning plants, leaching

Question 17

why is nitrogen fixation important

Answer 17

all living organisms depend on this process, just as they depend on photosynthesis for their energy

Question 18

what is assimilation

Answer 18

evidence that many plants take up organic compounds directly

Question 19

what are two things that impact the nutrient cycles and effects pollution

Answer 19

human population growth and acid rain

Question 20

why is plant nutrition research important

Answer 20

to overcome soil deficiencies and toxicities

Question 21

how is plant nutrition research being done

Answer 21

select and develop varieties of plants rather than amending soil; phytoremediation; manipulate biological N fixation

Question 22

what is the phosphorus cycle

Answer 22

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