lec 18- plant nutrition

Question 1

how do plants gain nutrients?

Answer 1

by taking up ions through their roots

Question 2

what is leibig’s law of the minimum?

Answer 2

plant growth is determined by the scarcest resource available (limiting factor)

Question 3

what nutrients limit growth?

Answer 3

nitrogen, phosphorus, potassium

Question 4

what is the historically common problem with the adage of NPK fertilizers?

Answer 4

one nutrient is added when another is the limiting factor, resulting in no increase in yield and fertilizer run off

Question 5

what are the scientific approaches to the common problem with NPK fertilizers?

Answer 5

increased fertilizer price, specific blends for crops, soil and plant is tested and returned with identified limiting mineral, farmers fertilize with limiting mineral

Question 6

about how much of the world is supported by synthetic nitrogen fertilizers?

Answer 6

about 50%

Question 7

what are the consequences of synthetic fertilizers?

Answer 7

dramatic increased crop yield, pollution from excess nitrates and phosphates in run-off water

Question 8

what is the Haber process?

Answer 8

a process that converts nitrogen gas into ammonia gas which then turns into a salt like ammonium nitrate to be used in fertilizer, bad for environment

Question 9

how was potassium originally prepared?

Answer 9

boiling wood ashes in a pot, potash, turns into potassium

Question 10

does Canada have the largest potash deposit for potassium?

Answer 10

yes

Question 11

how is phosphorus obtained?

Answer 11

by mining phosphorus rock

Question 12

what are the two factors of deficiency symptoms of a nutrient in a plant?

Answer 12

-the role of the element in the plant
-ability to translocate from older to younger leaves

Question 13

what are the effects of mobility on symptoms of nutrient deficiency ?

Answer 13

mobile- will move from older to newer leaves, older leaves will develop symptoms first
immobile- will not move to young leaves, young leaves will develop symptoms first

Question 14

what does root mineral uptake deplete?

Answer 14

nutrients near the roots, creating a nutrient depletion zone

Question 15

how do plants bypass nutrient depletion zone?

Answer 15

by extending roots beyond depletion zones to obtain minerals from soil

Question 16

what are the optimal levels of pH for soil and which pH causes deficiency symptoms?

Answer 16

good pH = 5-6
bad pH = smaller than 4.5 or larger than 6.5

Question 17

why is soil negatively charged?

Answer 17

to attract positively charged minerals like sodium, potassium, and calcium that stick to soil and don’t wash away. negatively charged ions will wash away

Question 18

how do root hairs free up soil bound cations?

Answer 18

1. root hairs secrete protons
2. root hairs respire, releasing CO2, resulting in bicarbonate ion and proton
3. proton is exchanged with cation on the soil particle

Question 19

how do cations enter root hairs?

Answer 19

by ion channels

Question 20

how do plants improve nutrient uptake?

Answer 20

symbiosis with fungi (mycorrhizae) and bacteria (nitrogen fixation)

Question 21

what does mycorrhizae do?

Answer 21

increase nutrient depletion zone several fold and increase uptake

Question 22

what do nitrogen fixating bacteria do?

Answer 22

fixate nitrogen into a form plants can use