Cereals 2024 Week 9-B Growth Regulation in Cereals Flashcards
How does lodging occur?
lodging occurs when the forces of gravity pulling
stem to ground are greater than those keeping it
standing
Whats the key parameters of lodging? (2)
key parameters are
– stem strength
– crown roots
when lodging occurs it may be as a result of
…
stem lodging, root lodging or a combination of
both stem and root lodging
If the centre of gravity is higher, there is…
A greater lodging force
the centre of gravity is determined by : (2)
– height of stem
– weight of stem (and ear
lodging occurs because of….
– bending or breaking of stem bases
the key stem characteristics are : (3)
- stem diameter,
- stem thickness,
- degree of
lignification
What do modern wheat varieties have?
modern wheat varieties have short, thick stems and
the forces required to break/bend stems are usually
far in excess of the self weight moment in most crops
What is not very common lodging ?
What can also lead to stem lodging?
-lodging due to stem failure is not very common in wheat
crops
– the occurrence of stem disease, eyespot can also lead to stem
lodging
What crop is much more prone to stem failure lodging and why?
barley crops are much more prone to this type of
lodging as they tend to be taller with weaker stem
bases
What is root lodging?
the ability of the cereal root system to keep
roots anchored in the ground depends largely
on the thick basal regions of the roots - crown
roots, which only extend a few cm’s into the soil
What are important crown characteristics?(2)
– number and spread of crown roots
– crown root length and strength
Root lodging with crown: how does it occur?
root lodging occurs when the crown root system
rotates through the soil profile under a high
lodging pressure (overturning force)
Reducing the risk of Lodging list factors that help: (3)
What can help reduce the risk of lodging (in terms of chemically?
1- decrease crop height
2-* increase stem strength
– increase stem diameter
– increase stem thickness
3* increase root anchorage
– by increasing crown root volume
– by having firm seedbed characteristics?
Growth regulators
How do you assess the lodging risk?
1* use the ‘standing power’ ratings when choosing
varieties
– shortness of straw
– strength of straw
2* site factors
– fertility of the field
– site aspect : is it exposed to wind effects
3* sowing date
– most relevant to winter wheat, e.g. higher lodging
risk with early sowings unless sowing rates are
reduced significantly