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205; BB Adaptation > L2: Strategies for acquiring nutrients > Flashcards

L2: Strategies for acquiring nutrients Flashcards

1
Q

what morphology of the plant reflects their strategies to acquire nutrients

A

their roots

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2
Q

true or false, as soils age, the nutrients available in the soil decline

A

true

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3
Q

true or false, as soils age, N and P levels decline

A

true

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4
Q

true or false, plants tend to specialize in pH gradients

A

true

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5
Q

which elements are present between soil pH 6.5-7.5

A

P, N, Ca, Mg, K

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6
Q

which elements are present between soil pH < 6.5

A

Fe, Mn, Cu, Zn (heavy metals)

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7
Q

true or false, essential soil nutrients is dependent on soil pH

A

true

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8
Q

true or false, major nutrients decrease as you go down the soil

A

true

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9
Q

why are soils heterogenous environments

A
  • different soils are limited to different nutrients
  • nutrients change as soils age
  • soil pH is a major factor in determining nutrient availability
  • many species have distinct preferences for soil with a particular pH
  • within a soil, patches of different quality created at various scales by abiotic and biotic factors
  • many important nutrients have highest concentration at shallow levels in soils
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10
Q

what are the two functions of roots

A
  • acquisition of soil based resources

- plant stability

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11
Q

true or false, dicots and gymnosperms root system develops from tap root and branched laterals

A

true

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12
Q

true or false, monocots, tap root is lost and root system develops as fibrous adventitious roots from the base of stem, no secondary growth

A

true

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13
Q

true or false, rates of nutrient uptake depend on quantity of root surface area and uptake properties of that surface

A

true

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14
Q

where do roots develop

A

epidermis and are most dense behind 1 degree root tip

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15
Q

what is hydraulic redistribution

A
  • before rain: tap root redistributes water to lateral roots; can also assist adjacent plants
  • daytime: transpiration; water to canopy
  • after rain: water storage
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16
Q

what pressure limits root growth

A

> 2-3 MPa

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17
Q

what are cold, anaerobic soils nitrogen form

A

high in dissolved organic nitrogen, low on nitrate ion

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18
Q

what are warm, aerobic soils rich in

A

nitrate ions

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19
Q

what nitrogen do arctic plants prefer

A

dissolved organic nitrogen

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20
Q

what nitrogen does Picea glauca prefer

A

amino ions

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21
Q

what nitrogen does barley prefer

A

inorganic N

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22
Q

how do plant communities differ their nitrogen consumption

A

timing, depth, chemical form of N uptake

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23
Q

true or false, plant symbiose with nitrogen fixing bacteria to gain nitrogen

A

true

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24
Q

how do plant acquire nitrogen from the air

A
  • plants may assimilate NO2 from the air
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25
Q

why are air nitrogen accumulating plants possible helpful to the urban pollution

A

act as N sinks

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26
Q

true or false, plants only take up inorganic P

A

true

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27
Q

how much percentage of P are present in agric soils

A

30-70%

28
Q

how much percentage of P are present in forest soils

A

80-95%

29
Q

what enzyme do roots produce to hydrolyze organic P to inorganic P

A

phosphotases

30
Q

true or false, some plants in low P soils excrete acidifying or chelating compounds

A

true

31
Q

how much percentage of the carbon is fixed in the rhizosphere?

A

5-21%

32
Q

what are cluser aka proteoid roots

A
  • ability to excrete enzymes high in Proteaceae
  • form proteoid or cluster roots
  • excrete carboxylates, phenolics,phosphatases
33
Q

what do cluster roots look like

A
  • longitudinal rows of extremely hairy rootlets
34
Q

what families are cluster roots common in

A

Fabeaceae, cyperaceae, restionaceae

35
Q

where do cluster soils occur

A

soils that are impoverished with P

36
Q

true or false, cluster roots are non mycorrhizal or weakly mycorrhizal

A

true

37
Q

true or false, cluster roots are suppressed by increased P levels in soil

A

true

38
Q

what is Empodisma minus

A

wire rush; found in NZ bogs, Restionaceae, main constituent of peat

39
Q

what are Calcifuges

A

aka Acid soils

40
Q

what are the properties of calcifuges

A
  • modifies availability of many soil nutrients and solubility of Al
  • Al toxicity, major effect in acid soils
  • toxic effects mediated through inhibiting uptake of Ca and Mg
  • resist high levels of Al
  • plants are either Al excluders or Al accumulators
  • ## Most, including crop plants are Al excluders
41
Q

give examples of calcifuges, plants

A

hydrangea and tea an Al accumulator

42
Q

What are calcioles

A
  • alkaline soils
  • calcifuges have low capacity to utilise some micronutrients and P on high pH soil
  • occur on high pH soils
  • can’t resist Al in root environment, but tolerate high levels of Ca by storing it as crystals, sometimes in leaf hairs
  • often only found on parent material, eg. limestone
43
Q

what causes heavy metal soils

A

geologic or anthropogenic origin (eg. mine spoils)

44
Q

what do the plants growing on heavy metal soil develop their resistance on

A
  • tolerance

- avoidance via exclusion or by uptake followed by storage in vacuoles

45
Q

what are serpentine soils

A
  • unnaturally high in Ni, Co, Cr, Mg, but low levels of Ca, N and P
46
Q

true or false, flora of heavy metal soils are usually rich in endemic species

A

true

47
Q

what does ultrafamic mean

A

means the land came from the mantle

  • high Ni, Co, Cr
  • high pH
  • low nutrients
  • <0.1% of land surface
  • at least 34 endemic plant species are known
48
Q

What are hyperaccumulators

A
  • may contain very high levels of heavy metals
  • nearly 200 species are identified as Ni hyperaccumulators
  • can be used for locating mining sites; hybanthus floribundus
  • phytoremediation, remove metals from polluted areas
  • phytomining, eg. growing Brassica juncea with NH4SCN and gold
49
Q

What are halophytes

A
  • live in saline areas (salt marshes)

- species occur with high resistance to salt (halophytes)

50
Q

why is salinity a problem to plants

A
  • it causes low soil water potential which plants experience as water stress
  • specific ions may be toxic
  • high levels on NaCl can lead to an ion imbalance and deficiency symptoms
51
Q

true or false, some halophytes are succulents in response to physiological drought

A

true

52
Q

what are some strategies of halophytes to cope with extreme salinity

A
  • salt exclusion from roots (or from xylem)
  • salt glands ( salt bladders) that excrete excess salt
  • compartmentation of salt within cells (succulence)
53
Q

what are mycorrhizae

A
  • root symbiosis between plant and fungi
54
Q

true or false, a majority of higher plant species form these associations (mycorrhizae)

A

true

55
Q

what forms mycorrihizae interactions

A
  • all gymnosperms
  • 82% of angiosperms investigated to date
  • some ferns and bryophytes
  • occur terrestrially and on epiphytes
56
Q

what are the benefits of mycorrhizae interactions

A
  • enhance plant’s absorptive capacity below ground

- for some plants this is the primary way they acquire poorly mobile and scarce nutrients like P

57
Q

true or false, plants gain nutrients while fungus gains C

A

true

58
Q

true or false, Plants may also gain water from the association, may suppress infection by root pathogens, and may increase tolerance of plants to drought, high temp, pH extremes and heavy metals

A

true

59
Q

what are the 4 different types of Mycorrhizal association

A
  1. ) Arbuscular mycorrhizae (AM)
  2. ) Ectomycorrhiza (ECM)
  3. ) Ericoid mycorrhizae
  4. ) Orchid mycorrhizae
60
Q

describe arbuscular mycorrhizae

A
  • endomycorrhizae with arbuscules (exchange organs) within the cortex of the root cells
  • fungi are member of zygomycetes (form large spores)
  • fossils of these spores found that are as old as land plants
  • only about 150 species of fungi
  • little specificity between host and fungi
  • most widespread
61
Q

what are ectomycorrhizae

A
  • hyphae form a mantle or sheath around highly branched roots and hyphal network (hartig net) between cortical cells, also extend out into the soil
  • characteristic of certain woody plants, members of Figaceae, Pinaceae and Myrtaceae
  • usually basiodomycete or ascomycete
  • much greater host-fungus specificity
62
Q

true or false, when ECM and AM grow together in the same soil, ECM grows in the leaf litter whilst AM grows in the mineral layer

A

true

63
Q

What are Ericoid Mycorrhizae

A
  • occurs in members of Ericaceae
  • intermediate between AM and ECM
  • penetrate outer root cortical cells with hyphal spirals
  • can take up complex organic source of N and P
64
Q

true or false, the association of ericoid mycorrhizae with Ericaceae may contribute to dominance of Ericaceae in many cold, wet soils where decomposition slow

A

true

65
Q

What are orchid mycorrhizae

A
  • occurs in members of Orchidaceae and are often host specific
  • seeds will not germinate in the absence of mycorrhizal fungus
  • orchids then have an early non photosynthesis stage where it is entirely dependent on fungus nutrition
  • Like AM, intracellular growth with fungal coils produced
  • some orchids remain non photosynthetic eg. Gastrodia

205; BB Adaptation (5 decks)

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