Lecture 3

Question 1

What is the Crown and what does it do?

Answer 1

compressed stem at the soil surface.
– Key storage organ
– It is the growing point

Question 2

Why can turf tolerate short mowing heights?

Answer 2

• In turfgrasses, the meristem remains near
the surface of the ground, below the
mower blades

Question 3

What is the Apical Meristem?

Answer 3

located at top of crown. It

continually forms leaf primordia and cells for stem growth.

Question 4

What are Leaf Primordia? How many are there normally?

Answer 4

small protuberances just below apical meristem.

Normally between 5 and 10 but can vary from a few to 20 or more.

Question 5

define Senescence:

Answer 5

maturity or death

Question 6

Where does senescence start on turfgrass?

Answer 6

at the leaf tip and works its way downward and eventually falls away from the shoot.

Question 7

On the meristem, what leaves grow first?

Answer 7

The bottom leaves and they work their way up.

Question 8

What are the 2 types of Meristems that are present at the growing point?

Answer 8

Apical and Intercalary

Question 9

Define the Apical Meristem:

Answer 9

Produces new cells to continue stem development at the top of the crown

Question 10

Define Intercalary Meristem:

Answer 10

Responsible for leaf production and is located just below the apical meristem.

Question 11

What happens to the Intercalary Meristem when leaf primordia begin to develop at a fast rate?

Answer 11

The Intercalary Meristem divides into 2 meristems which are called the Upper Intercalary and the Lower Intercalary.

Question 12

What is the Upper Intercalary Meristem responsible for?

Answer 12

Produces cells for growth of the leaf blade.

Question 13

What is the Lower Intercalary Meristem responsible for?

Answer 13

It remains at the base of the leaf to continue development of the leaf sheath.

Question 14

Name the oldest and youngest parts of a leaf.

Answer 14

Oldest - Leaf Tip

Youngest - Base of the leaf sheath

Question 15

Following emergence of the leaf, sheath and blade

assume different shapes. explain:

Answer 15

– Leaf blade unfolds or unrolls and flattens out
– Sheath remains folded or rolled surrounded by
older leaf sheaths.

Question 16

As the tip of a leaf begins its upward

movement within the shoot….What happens to the next older leaf?

Answer 16

the next older leaf initiates sheath elongation.

This process happens over and over and over

Question 17

• Rate of new leaf emergence =

Answer 17

= rate of old leaf death

Question 18

What leaves have the highest photosynthetic rates

Answer 18

Young, Fully expanded leaves

Question 19

As far as leaf growth is concerned, how do long days or short days effect their growing habbits? Why?

Answer 19

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.

Question 20

What is Plastochron? How is it measured?

Answer 20

– Interval between emergence of two successive
leaves
Measured in days.

Question 21

Is it better to add Nitrogen in the Spring or the Fall? Why?

Answer 21

• 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

Question 22

What are the 3 principle types of thems that occur in turfgrass?

Answer 22

– crown
– flowering culm
– lateral stems (rhizomes/stolons)

Question 23

What makes the Flowering Culm and Lateral stems different from the Crown?

Answer 23

Length of Internodes. Crown has very short internodes while the others are much longer.

Question 24

Define what the Crown is.

Answer 24

highly contracted stem with nodes appearing to be stacked on top of each other

Question 25

Where do Crowns form?

Answer 25

Wherever new shoots develop
– Embryo
– Axillary buds
– Terminals of rhizomes and stolons

Question 26

On any given Node you might find:

Answer 26

1. One Leaf
2. Roots
3. Axillary buds=
   1. tillers
   2. rhizomes
   3. stolons

Question 27

what are Determinate Rhizomes?

Answer 27

short, turn upward to form a new
shoot.
– Kentucky bluegrass, creeping red
fescue

Question 28

What are Intermediate Rhizomes?

Answer 28

– long, branch at the nodes

– Bermudagrass