Lecture 3 Flashcards
(28 cards)
What is the Crown and what does it do?
compressed stem at the soil surface.
– Key storage organ
– It is the growing point
Why can turf tolerate short mowing heights?
• In turfgrasses, the meristem remains near
the surface of the ground, below the
mower blades
What is the Apical Meristem?
located at top of crown. It
continually forms leaf primordia and cells for stem growth.
What are Leaf Primordia? How many are there normally?
small protuberances just below apical meristem.
Normally between 5 and 10 but can vary from a few to 20 or more.
define Senescence:
maturity or death
Where does senescence start on turfgrass?
at the leaf tip and works its way downward and eventually falls away from the shoot.
On the meristem, what leaves grow first?
The bottom leaves and they work their way up.
What are the 2 types of Meristems that are present at the growing point?
Apical and Intercalary
Define the Apical Meristem:
Produces new cells to continue stem development at the top of the crown
Define Intercalary Meristem:
Responsible for leaf production and is located just below the apical meristem.
What happens to the Intercalary Meristem when leaf primordia begin to develop at a fast rate?
The Intercalary Meristem divides into 2 meristems which are called the Upper Intercalary and the Lower Intercalary.
What is the Upper Intercalary Meristem responsible for?
Produces cells for growth of the leaf blade.
What is the Lower Intercalary Meristem responsible for?
It remains at the base of the leaf to continue development of the leaf sheath.
Name the oldest and youngest parts of a leaf.
Oldest - Leaf Tip
Youngest - Base of the leaf sheath
Following emergence of the leaf, sheath and blade
assume different shapes. explain:
– Leaf blade unfolds or unrolls and flattens out
– Sheath remains folded or rolled surrounded by
older leaf sheaths.
As the tip of a leaf begins its upward
movement within the shoot….What happens to the next older leaf?
the next older leaf initiates sheath elongation.
This process happens over and over and over
• Rate of new leaf emergence =
= rate of old leaf death
What leaves have the highest photosynthetic rates
Young, Fully expanded leaves
As far as leaf growth is concerned, how do long days or short days effect their growing habbits? Why?
Long days = faster and more erect
Short days = slower and more horizontal
This happens because of the amount of time they have to use the sun to photosynthesize. Shorter days means they need to expose more of their leaf tissue to soak up the rays. thus growing more horizontal.
What is Plastochron? How is it measured?
– Interval between emergence of two successive
leaves
Measured in days.
Is it better to add Nitrogen in the Spring or the Fall? Why?
• N added in long days (spring):
– stimulates shoot growth, leaf elongation
– (at the expense of root growth and uses up stored
food in the crown)
– This weakens plant going into the summer
• N added in short days (fall) increases:
– root growth
– tiller production
– storage of food reserves
What are the 3 principle types of thems that occur in turfgrass?
– crown
– flowering culm
– lateral stems (rhizomes/stolons)
What makes the Flowering Culm and Lateral stems different from the Crown?
Length of Internodes. Crown has very short internodes while the others are much longer.
Define what the Crown is.
highly contracted stem with nodes appearing to be stacked on top of each other
