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

1. 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

2. Introduction • Ability to plant mechanically is critical to long term sustainability in Florida • Approximately 25-50% of hectares mechanically planted annually

3. 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

4. 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

5. 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

6. 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

7. 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

8. Measurements • Stalk internode lengths were determined using a tape • Internode diameters were determined using a caliper

11. Average Internode Length

12. 797**Average Internode Diameter

13. 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

14. 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

15. 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

16. 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

17. A NS A NS B NS B A B

18. NS A NS A B NS A B B

19. 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

20. 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

21. Questions