Lecture 8: Growth, development, reproduction and response to environmental stress Flashcards
growth
irreversible quantitative increase
- population size
- size
- dry weight
development
qualitative changes in body structure/function
tropic growth
growth in response to an unidirectional stimulus
where is light sensed?
the coleoptile tip
phototropic signal
auxin
- it bends by elongating the cells
apical dominance
if plant keeps growing in height and no side branches grow out
- due to higher concentration of auxin at apex
Gibberellins
induce increase in plant height when sprayed on intact plant
seed dormancy
- generally dormant just after being shed
- sometimes wont germinate even if conditions are optimal
- most frequently due to abscisic acid (ABA)
- can be due to too strong of seed coating
- sometimes they cant grow if they receive specific light frequency (ex. it grows more when it finishes with red light)
reproduction is angiosperms
asexual: parts of vegetative body regenerates shoots and roots (no gametes)
sexual: flowering, pollination and double fertilization
photoperiodism
- a combination of light length and day length that induces a plant to flower
- a hormone florigen moves from induces leaf to shoot apex where flowers are produces
short day plant
indicate flowering when day length is SHORTER than critical photoperiod
long day plant
indicate flowering when day length is LONGER than critical photoperiod
day neutral plant
flowering depends on the number of leaves produced
types of environmental stress
- biotic stress (herbivory, wounding, pathogens)
2. abiotic stress (chemical, physical)
responses to environmental stress
- avoidance/resistance- plant doesn’t allow stress to develop in tissues
- tolerance- can survive and resume growth
- escape
