Crop Physiology Flashcards
metabolic energy transformations
critical for plants’ survival
photosynthesis
plants convert sunlight energy to chemical energy
respiration
plants convert sugars and starches to energy for metabolism of cells
transpiration
loss of water from the stomata of plants
symbiotic nitrogen fixation
process that makes atmospheric nitrogen available to legumes
photoperiodism
the reaction of plants to changing lengths of darkness
vernalization
photoperiod response during the winter that is important for triggering flowering in the spring
plants are categorized as what based on their life cycle
annual, biennial, or perennial
metabolism
the group of vital biochemical reactions that occurs in the cells of living organisms
mesophyll cells have ____________ that include green ____________
chloroplasts; chlorphylls
light reactions
harvest sunlight for energy
two main energy compounds
ATP and NADPH
carbon-fixation reactions
Calvin cycle = C3 cycle
C3 plants (temperate regions)
alfalfa, wheat, soybeans, cotton, tobacco, peanuts
C4 plants (tropical enevironments)
corn, sorghum, millet, big bluestem, Indiangrass, switchgrass
CAM plants (stomata only open at night; more drought tolerant)
cacti and pineapple
photorespiration
reverse photosynthesis; occurs during a drought and uses more carbon energy
sugars from photosynthesis
ATP energy
glucose + oxygen ->
carbon dioxide + water + energy
four primary processes of respiration
- glycolysis (produces energy)
- pyruvate enters the mitochondria and is split into CO2 and acetyl CoA
- Krebs cycle uses acetyl CoA to produce ATP and NADH
- oxidative phosphorylation occurs within the mitochondria
photosynthesis characteristics
- occurs in light
- produces sugars
- stores energy
- uses H2O
- uses CO2
- releases O2
respiration characteristics
- occurs in dark and light
- uses sugars
- releases energy
- produces H2O
- produces CO2
- uses O2
higher temp =
greater respiration
transpiration is important for:
- cooling the plant
- movement of nutrients within the plant
- uptake of mineral nutrients
five factors that affect transpiration
- # and size of stomata
- presence of soil moisture
- air temperature
- air moisture content (humidity)
- wind or air movement increases the transpiration pull
evapotranspiration
the plant’s total water use
ET ratio
weight of water required to produce the weight of the crop’s dry matter
pubescence
short hairs that cover leaf surfaces
cuticle
thick, waxy coating on leaves
symbiotic nitrogen fixation
a process that makes atmospheric nitrogen available to some plants
nitrogen fixed per year (lbs/ac) of alfalfa, red clover, and soybeans
alfalfa: 70-200
red clover: 60-200
soybeans: 20-200
nodule formation
- root hairs grow and release root exudates
- rhizobia attatch to the root hair surface
- root hairs curl and trap rhizobia
- rhizobia digest the cell wall
- rhizobia induce division of the root cells
- nodule is formed from the protrusion of the root cells to the root surface
- bacteria of the individual root cells develop the nitrogenase enzyme and fix atmospheric nitrogen
phytochrome
pigment that senses changes in amounts of red and far-red light
short-day flowering response
late summer of fall-flowering plants
do not flower in the longest days of the summer
ex. corn, soybeans, cotton, and rice
long-day flowering response
flower when the photoperiod is longer than a certain period
spring or early summer flowering plants
ex. smooth bromegrass and wheat
day neutral flowering response
flower after a certain age or when a certain level of growth has been achieved
ex. ever-bearing strawberries, cucumber, and tomatoes
dormancy response
perennial plants have a dormancy period
seed germination response
light activates vegetative growth of the epicotyl
wheat requires ____ photoperiods and ___ temperatures
short; low
dry matter
the weight of all the components of a plant minus the water
general development stages
- seed
- seedling
- vegetative
- flowering
- fruit
- seed
- senescence
growing degree days
an index of heat accumulation (or heat units over time)
what temperature range is beneficial to crops
50 - 86 degrees F