Lecture 14: Light interception 2. Evolution of crop plants Flashcards Preview

APS206: Biotechnology & Food Security > Lecture 14: Light interception 2. Evolution of crop plants > Flashcards

Flashcards in Lecture 14: Light interception 2. Evolution of crop plants Deck (27)
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1
Q

light interception is affected by:

A
  • the number of leaves (LAI)
  • leaf duration - the longer leaves last the more light they will intercept
  • leaf orientation (some, shape, vertical separation)
  • AND
  • Heliotropism (leaf movement)
  • Structures other than leaves - awns, stems, ears
2
Q

why is it optimal leaves move?!

A

No fixed leaf orientation can be optimal in the relation to a moving light source (the sun)

3
Q

heliotropism:

A

moving of leaves in relation to the sun

4
Q

Diaheliotropic:

A

leaves remain perpendicular to the sun

5
Q

Paraheliotropic:

A

leaves remain parallel to the sun

-try to avoid light interception, may be under stress i.e. water stress

6
Q

two forms of heliotropism:

A
  • diaheliotropic

- paraheliotropic

7
Q

solar trackers: & e.g

A
  • orientate towards the sun
  • soybean
  • sunflower
  • cotton
  • townsville lucerne
8
Q

photosynthesis is always a balancing act betwee

A

light interception and water loss

9
Q

all aerial parts of grasses are ___ at earlier stages of development

A

GREEN

==photosynthesises!

10
Q

Wheat structure:

A
  • flag leaf: which subtends the ear (hugs), are erect and high in the canopy
  • awns (spiky bits out v top)
11
Q

source of photosynthates in wheat during development:

A
  • ear formation: from the leaves
  • Flowering (anthesis): from upper leaves and ear
  • 2 weeks after flowering: flag leaf stem and ear
  • 4 weeks after: flag leaf
12
Q

WHEAT: anthesis occurs and ears have

A

covers –> which are green, can photosynthesise

13
Q

light interception by structures other than leaves: e.gs of plants

A
  • wheat
  • barley
  • maize
  • rice
14
Q

light interception by structures other than leaves: contributions made by day varies considerably:

  • wheat
  • barley
  • maize
  • rice
A
  • wheat: 10-49% (usually > flag leaf )
  • Barley: 26-76% (awns that extend form the lemmas of the florets)
  • Maize: may be negative
  • Rice: 8-23% (flag leaf persists longer, ear bends below canopy)
15
Q

in wheat, in the first week after anthesis, ear photosynthesis may account for

A

3/4 of grain growth

16
Q

Donald’s Wheat Idiotype: (idealised appearance)

A
  • a large ear (specifically many florets per unit of dry matter of the tops)
  • an erect ear
  • awns
  • few,small erect leaves
  • a single short, strong stem (culm)
17
Q

what are tillers ?

A

side shoots at base of stem

18
Q

lodging in wheat:

A

when the crop falls over, for example after a storm

19
Q

Giggs Wheat: reduced tillering tin (tiller inhibition) mutant

A
  • larger spikes & robust stems
  • greener leaves
  • higher photosynthesis in penultimate leaf
20
Q

Effects of over expression of SPIKE in rice

A

a significant yield enhancement (13-16% grain yield) in IR64, plus improved plant architecture, without changing grain quality or growth period, achieved by expression of SPIKELET NUMBER (SPIKE) from an Indonesian rice landrace.

21
Q

what is a Spikelet in rice?

A

RICE FLOWERS

22
Q

Optimising root systems: shallow rooting promotes

A

phosphorus capture

23
Q

Optimising root systems: root branching affects

A

soil exploration

24
Q

Optimising root systems: root hairs promote

A

phosphorous capture

25
Q

Optimising root systems: root cortical parenchyma reduce

A

metabolic coat

26
Q

Optimising root systems: narrow xylem restricts

A

water flow

27
Q

Optimising root systems: deep rooting increases

A

water & nitrogen capture