Use of trinexapac-ethyl to improve seed quality in mechanically planted sugarcane in Florida

C.R. Rainbolt, J.M. Shine, G. Powell, P. Grose, J. Larsen

Introduction

• Ability to plant mechanically is critical to long term sustainability in Florida

• Approximately 25-50% of hectares mechanically planted annually

Factors Limiting Mechanical Planting

• Poor stand quality compared to hand planting

• Requires more seed cane per acre in order to achieve a stand similar to hand planting– Mechanical damage to buds– Short billets are more susceptible to stalk rot– Seed cane metering device on planter is not precise

Trinexapac-ethyl• Trinexapac is a foliar absorbed plant

growth regulator • Interferes with gibberellic acid metabolic

pathway• Affects cell elongation, chilling

tolerance, and photoperiod response• Preliminary research indicated that

trinexapac can successfully reduce internode length in sugarcane

Objectives

1.Evaluate the efficacy of trinexapac for shortening internode length in sugarcane

2. Determine if planting seed cane treated with trinexapac results in more consistent emergence

Treatment with Trinexapac

• Commercial fields of CP 84-1198, CP 78-1628, CP 80-1743, CP 89-2143, CP 88-1762, and CL 77-797 were selected for treatment

• Trinexapac at 183 g ai/ha was applied at canopy closure (late spring)

• An additional 148 g ai/ha was applied ~6 weeks later

Seed Cane Data Collection

• 6 subsamples of trinexapac treated and nontreated seed cane of each cultivar were collected on October 17, 2005

• Each subsample consisted of 5 randomly collected stalks

Measurements

• Stalk internode lengths were determined using a tape

• Internode diameters were determined using a caliper

Average number of internodes per stalk

0

5

10

15

20

25

30

1198 1628 1743 2143 797 1762

cultivar

# o

f in

tern

od

es

Control

Trinexapac

NS at P= 0.05

Palisade Seed Piece 2005Average Internode Lengths

0

50

100

150

200

250

300

1198

Con

trol

1198

Trin

exap

ac

1628

Con

trol

1628

Trin

exap

ac

1743

Con

trol

1743

Trin

exap

ac

2143

Con

trol

2143

Trin

exap

ac

0797

Con

trol

0797

Trin

exap

ac

1762

Con

trol

1762

Trin

exap

ac

cultivar

inte

rno

de

len

gth

(c

m)

Average Internode LengthCultivar Trinexapac Control LSD

--------length ± SD (cm)------- (P=0.05)

CP84-1198 13.65 ± 1.81 14.18 ± 3.21 NS

CP78-1628 11.48 ± 3.04 12.69 ± 3.35 0.80

CP80-1743 12.86 ± 1.92 13.02 ± 2.88 NS

CP89-2143 9.01 ± 1.55 11.09 ± 2.68 0.52

CP88-1762 9.97 ± 2.03 10.79 ± 1.99 0.46

CL77-797 10.08 ± 2.01 9.61 ± 2.14 NS

797**Average Internode DiameterCultivar Trinexapac Control LSD

-------diameter ± SD (mm)------- (P=0.05)

CP84-1198 23.91 ± 2.05 23.58 ± 2.29 0.29

CP78-1628 23.21 ± 1.61 23.55 ± 2.80 NS

CP80-1743 24.93 ± 3.63 23.53 ± 3.45 0.43

CP89-2143 28.37 ± 2.95 24.52 ± 3.49 0.62

CP88-1762 26.07 ± 1.91 24.01 ± 2.00 0.35

CL77-797 26.65 ± 2.41 27.13 ± 2.18 0.31

Seed Cane Measurements Summary

• Treatment with trinexapac resulted in significantly shorter average internode lengths for CP 89-2143, CP 88-1762, and CP 78-1628

• Treatment with trinexapac resulted in larger internode diameters for all

• The average number of internodes per stalk and stalk weight were not affected by trinexapac

Field Trial

• Seed was mechanically harvested from each cultivar (site)

• Transported to a single site for planting in a randomized complete block design

• Cultivar was main treatment and split plots were treated and untreated

Field Trial Planting

• Plots were 8 rows wide 12.2 m by 12.2 m long

• Seed pieces (billets) were randomly chosen and planted November 17-19, 2005

• Single row placed end to end

• Thimet 20G was applied and seed cane was covered on November 19, 2005

Field Trial Data Collection

• Billets and nodes were counted in a 3.05 m section of 2 rows

• Shoot counts were conducted approximately every 2 weeks following emergence

• Shoots were counted in the middle 2 rows of each split-plot

• Trial will be taken to yield and repeated in 2006

0

2000

4000

6000

8000

10000

12000

14000

CP80-1743 CP88-1762 CP89-2143 CP78-1628 CP84-1198 CL77-797

Sho

ots

per

Hec

tare

Palisade Untreated

Shoot CountsDate 12/28/2005 - First Count

Planted 11/17-19/2005

NS

NS

A

AA

NS

B

BB

0

5000

10000

15000

20000

25000

30000

35000

40000

CP80-1743 CP88-1762 CP89-2143 CP78-1628 CP84-1198 CL77-797

Sho

ots

per

Hec

tare

Palisade Untreated

Shoot CountsDate 4/10/2006 - Ninth Count

Planted 11/17-19/2005

NS

B

A

A

A

B

B

NS

NS

Field Trial Summary

• The number of billets per plot was not different between treated and untreated plots

• The number of nodes per meter was only significantly higher in CP89-2143 and CP80-1743

• Treatment with trinexapac resulted in higher counts with CP89-2143, CP80-1743, CP78-1628

Conclusions

• Early results indicate that trinexapac can be used to improve seed cane quality and shoot counts in some cultivars

• Yield results will ultimately determine if there is value

• Modified application timings and doses may be necessary with some cultivars

• Registration for seed treatment is dependent ton ripener use registration

Questions