Coordination And Control Plants Flashcards
(18 cards)
Outline plant growth
During growing season
Cell division takes place at apex of plant - tissue called apical meristem
Cells enlarge in a region below tip - zone of elongation
Certain points of year internode also elongates
Auxin
Produced: Apical Meristem
Growth Effect: stimulate elongation of cells
Cytokinins
Produced: Actively Dividing Tissues (meristematic)
Effect: Promote cell division - especially in combination w/ auxins
Gibberellins
Produced: Apical Buds and Leaves
Effect: Stimulate Elongation of Internodal Regions
Auxin Action
•prod apical meristem
•diffuse down shoot -> ZOE
•bind to specific receptors on CSM new cells
•membrane pumps move H+ into cellulose cell wall
•acidification cell wall activates elastins - loosen linkages btwn cellulose microfibrils - allowing slippage - flexable
•cells absorb water by osmosis - cells expand as extra water exerts incr hydrostatic pressure against them
•more auxin recieved ZoE - more effect allows cells expand
Long Day Plants
flower only if daylength exceeds a critical value
Short Day Plant
flower only if the daylength is less than a critical value
Types of phytochrome pigments
P660
P730 - far red
What happens during night
slow conversion p730 to p660
What accumulates during the day
p730
What happens when one light absorbs another type
rapid conversion
What is p730 known as
the physiologically active form
can stimulate or inhibit
it is critical to flowering
p730 in LDP
stimulatory
high level
p730 in SDP
inhibitory
removal required for flowering
long day short night flowering
LDP yes
SDP no
short day long night flowering
LDP no
SDP yes
short day long night - interrupted short light period
LDP yes
SDP no - not enough time to conv rapid conv back slowly
types of manipulation
SDP - expose short period light during night
-delay for several months
bring plants to consumer when they command high prices
