pre-bloom growth and development post bloom plant activity ... of plant growth regulators 09.pdf ·...

Pre bloom growth and development Pre-bloom growth and development determines the yield potential› At first bloom 80-90% of the crop that will › At first bloom 80-90% of the crop that will be harvested is on the plant

Post bloom plant activity determines the Post bloom plant activity determines the yield and quality

The size of the plant (number of i t d ) t fi t bl mainstem nodes), at first bloom

determines the yield potential Fi t bl 8 d b l th First bloom -- 8 nodes below the terminal

7 l l t t› 7 or less -- early cutout› 9 or more -- rank growth

Elongation rate - change in internodeElongation rate change in internodelength - measure of top 5 nodes & first mature internodef m- Stress vs vigorous

Boll load - Carbohydrate supply in Boll load - Carbohydrate supply in the plant - the boll load drives the development of the plantdevelopment of the plantMoisture, Nitrogen, Light

Plant A Plant heightNumber f n d

Average = InternodeLength

of nodes g

9 Nodes

2615 = 1.7” AIL 15

AIL at first bloomf mDryland – > 1.1 Irrigated - 1.5” -1.75”

6 Nodes

Cotyledon nodes

Always try to make cotton Always try to make cotton on the front end of the

growing season

rather than on the back end

E l S Fi t FlEarly Square – First Flower

Stress from square initiation to first flower is the most critical first flower is the most critical period of yield determination

Stress during this period will limit the potential number of fruit

Fruit sensitivityHigh Small boll y

to shed

Small squaresquare

14 days 14 days after bloom

Low Bloom

CROP SET CROP SET 1-2 BALE YIELD POTENTIAL

AT EARLY BLOOM 1 2 BALE YIELD POTENTIAL

AT EARLY BLOOM 80-95% OF THE CROP TO BE HARVESTED IS

ALREADY ON THE ALREADY ON THE PLANTPLANT.

Anti-giberillinReduces internode length Restricts vegetative growth Increases leaf thickness and concentrates chlorophyllE h li i Enhances earliness in some cases Will not shrink cottonShould not be applied for yield Should not be applied for yield enhancement – increased yield is a bonusMC is a plant growth management tool MC is a plant growth management tool

Benefits Risks

Reduces Plant Size› Equipment operation

May cause early cutoutq pm p

› Less lodging and boll rot

Can increase li

cutoutIncreases drought stress

earliness› harvest and defoliation

scheduling

May reduce yieldGreatest risk is to g

› can help early retention

Sometimes increases i ld

pre-bloom cotton at high rates

yield

Internode growth or cell expansion is Internode growth or cell expansion is a very sensitive indicator of stress or luxuriant growth conditionsgWhen planting date is the same, the differences in plant height are due to

i i i i d l h variations in internode length - not the number of nodes and internodes. I t d th b d Internode growth can be used as a measure of plant vigor in the past, present and predict future growthpresent and predict future growth

Indication of boll load Indication of cutoutVigor of the plantIndication of water stressIndication of nitrogen stressnd cat on of n trogen stress

Nodes Above White FlowerNAWF

1. Water and nitrogenmanagement

2. Indication of boll load 3. Indication of cutout4. Vigor of the plant

A declining NAWF is indicative of a d i h t th ti ti it decrease in photosynthetic activity An increased carbohydrate demand by th b ll l dthe boll loadWater stress

Early BloomCarbohydrate

production

Early Bloom

production

Seed and lint demand

Vegetative DemandDemand

Late BloomCarbohydrate

production

Late Bloom

Seed and production Seed and lint demand

Seed and li d d

Vegetative lint demand

gDemand

8 NAWF

6 NAWF 6 NAWF

5 NAWF

3 NAWF

MepiquatMepiquat ChlorideChloride Use StrategyUse StrategyMepiquatMepiquat ChlorideChloride Use StrategyUse StrategyMepiquatMepiquat Chloride Chloride Use StrategyUse StrategyMepiquatMepiquat Chloride Chloride Use StrategyUse Strategy

P bl h h / d P bl h h / d P bl h h / d P bl h h / d •• Prior to bloom, use height/node ratio Prior to bloom, use height/node ratio (average (average internodeinternode length)length)

•• Prior to bloom, use height/node ratio Prior to bloom, use height/node ratio (average (average internodeinternode length)length)•• If average If average internodeinternode length is 1.2 length is 1.2

inches or greater, use 3inches or greater, use 3--4 ounces of 4 ounces of M i tM i t t i h d t t h h d t i h d t t h h d

•• If average If average internodeinternode length is 1.2 length is 1.2 inches or greater, use 3inches or greater, use 3--4 ounces of 4 ounces of M i tM i t t i h d t t h h d t i h d t t h h d MepiquatMepiquat at pin head to match head at pin head to match head squaresquare

•• If average If average internodeinternode length is less than length is less than

MepiquatMepiquat at pin head to match head at pin head to match head squaresquare

•• If average If average internodeinternode length is less than length is less than •• If average If average internodeinternode length is less than length is less than 1 inch, application is probably not 1 inch, application is probably not necessarynecessary

•• If average If average internodeinternode length is less than length is less than 1 inch, application is probably not 1 inch, application is probably not necessarynecessarynecessarynecessarynecessarynecessary

F ll bl d b h Following bloom, use nodes above white flower› Nodes above white flower should be hi hest › Nodes above white flower should be highest at first bloom, and decrease approximately one node per week until cutout

› If NAWF is 8 or higher, mepiquat should be used at 8-12 ounces at first bloom if cotton is not (or likely will not be) water cotton is not, (or likely will not be) water stressed in the next seven days

› More mepiquat is required for the same l li i i d l dresults as application is delayed

Also during blooming, a good technique is determination of the internode length between the fourth and fifth node from between the fourth and fifth node from the top of the plant› If this internode length is greater than 2.5

inches the plant should be evaluated for inches, the plant should be evaluated for another application

If the plant is well fruited, the fruit load will soon stress the plant and decrease vegetative soon stress the plant and decrease vegetative growthIf the plant is not well fruited, a heavy rate of mepiquat chloride will likely be needed to help p q y ppartition growth from vegetative to reproductive

12 The only internodes expanding

t 5 E thi b l it

4

3are top 5. Everything below ithas hardened.

5

internodelength

Do not usemepiquat chloride m p quat ch or

on drought on drought stressed cotton stressed cotton

The Performance of Growth Regulators in Oklahoma CottonVariety: FM 9063 B2F Planted: May 16, 2007

Fertility, Rainfall & Irrigation-300 lbs actual N preplant- Over 8 inches rain between planting & Matchhead app. (13” May-Sept.)- Furrow irrigation began 7/24 continuing weekly thru August (18” total)

The Performance of Growth Regulators in Oklahoma Cotton

The Performance of Growth Regulators in Oklahoma CottonTotal # Mainstem Nodes

18

19

20

16

17 abcc

abc abc abc abc

13

14

15Trt 1Trt 2Trt 3Trt 4Trt 5T t 6

ct 2 +

3

10

11

12Trt 6Trt 7

Gin

out

e 1.

5 +

2

e 2

+ 3

e 2

+ 3

+

ated

8

9

10

Mep

ex

Mep

ex

Stan

ce

Stan

ce

Pent

ia

Stan

ce

Unt

rea

7Total # Mainstem Nodes

M

The Performance of Growth Regulators in Oklahoma Cotton

NAWF-essentially no difference between treatments(Mepex slightly less than untreated)( p g y )

NACB – Mepex, Mepex Ginout & Stance significantly different from untreated (1.08-1.6 vs. 3.15)

The Performance of Growth Regulators in Oklahoma Cotton

nout

5 +

2

+ 3

+ 3

+ 3

pex

pex

Gin

nce

1.5

nce

2 +

ntia nce

2 +

trea

ted

Mep

Mep

Stan

Stan

Pen

Stan

Unt

No treatment lint yield was different from untreatedPentia treatment did produce more lint than Mepextreatment

The Performance of Growth Regulators in Oklahoma Cotton

3

Gin

out

1.5

+ 2

2 +

3

2 +

3 +

3

ed

Mep

ex

Mep

exG

tanc

e 1

tanc

e 2

entia

tanc

e 2

ntre

ate

M M S S P S U

The Performance of Growth Regulators in Oklahoma Cotton

nout

5 +

2

+ 3

+ 3

+ 3

d

pex

pex

Gin

ance

1.5

ance

2 +

ntia

ance

2 +

ntre

ated

Mep Me

Sta

Sta

Pen

Sta

Un

The Performance of Growth Regulators in Oklahoma Cotton

3

.5 +

2

+ 3

+ 3

+ 3

ed

epex

.Gin

tanc

e 1.

tanc

e 2

entia

tanc

e 2

ntre

ate

Me M.

St St Pe St U

The Performance of Growth Regulators in Oklahoma Cotton

3

inou

t

.5 +

2

+ 3

+ 3

+ 3

ed

epex

epex

G

tanc

e 1.

tanc

e 2

entia

tanc

e 2

ntre

ate

Me Me

St St Pe St U

When plant growth regulators are used correctly, the crop normally shows

li f i i if d il earlier fruiting, more uniform and easily managed plants, earlier application of h t id nd i h tin harvest aids, and easier harvesting conditionsHi h i ld b b b t i t Higher yield may be a bonus, but is not to be expected under all conditions