Introduction

This article was first published in the 2007 Proceedings of the International Society of Sugar Cane Technologists.

In Florida, sugarcane is grown on both organic (70%) and mineral "sandland" soils (30%; VanWeelden et al. 2019). The Canal Point (CP) breeding program has been very successful in producing sugarcane cultivars for organic soils in Florida. However, the CP program historically tested new clones on mineral soils only during the latter part of selection stages until the recent start of a new sandland breeding program in which all stages of new clones are tested in mineral soils. Studies on historical data have shown no/minimal yield gains on sandy soils (Edme et al. 2005). Consequently, growers on sandland soils have expressed interest in testing germplasm ("foreign cane") released from programs specifically targeting mineral soils. This EDIS document summarizes field studies established to test foreign cane on Florida sandlands. A set of three experiments was established to evaluate 50 foreign cane genotypes from 11 countries for yield and disease resistance.

Methodology

In experiment 1, 50 clones were planted on a sandy soil at Hilliard Brothers Farms in two replicates on November 13, 1997, in two-row-wide plots with 4.5 m row length (Table 1). This experiment included 21 clones from the United States (CP, TCP, LCP, US, L), ten clones from China (Yuetang, CGS), five from Colombia (CC, EPC) three from New Guinea (NG), three from Taiwan (ROC), two from the Dominican Republic (CR), two from India (IND, Green German), and one each from Argentina, Brazil, Mexico, and the Philippines. In all experiments, sugarcane yields were recorded 12 months after planting by established methods (Gilbert et al. 2006). Field observations of disease were recorded in the spring of each year.

Following plant-cane harvest in experiment 1, 23 high-yielding clones were selected to advance to experiment 2 (Table 2). These clones were planted in single-replicate plots at three mineral soil locations in November 1998 in six-row-wide plots with 3.0 m row length. Field disease observations were recorded in May 1999 and final plant-cane yield data were recorded in November 1999.

Following plant cane harvest of experiment 2, eight high-yielding clones were selected to replant at the same three mineral soil locations with six replicates per location in experiment 3 in November 1999 in three-row-wide plots with 10.6 m row length (Table 3). Field disease and yield data were collected for both the plant-cane (P) and first-ratoon (R) crops in experiment 3. In all experiments, the economic index used by the CP breeding program (Deren et al. 1995) was calculated to rank clones. In experiment 3, clones were ranked based on the sum of plant-cane and first-ratoon economic indices (Table 3).

Results and Discussion

The Yuetang clones in experiment 1 (Table 1) were notable for their large stalk weight and low plant population. Yields of 'Yuetang 85-1253' were 15 tons/acre of cane more than the second-ranked cultivar. Six Yuetang clones were in the top 13 for cane yield. The large stalk size recorded for the Chinese clones may be indicative of their selection for ease of manual harvesting in China. Economic indices of 11 of 13 clones with CP parentage were in the upper half, with none ranking lower than number 32. 'LCP 86-454' was notable for high plant population and low stalk weight. Clones originating from the United States tended to have high sucrose concentrations, with 12 of the top 14 sucrose concentration values recorded for these clones. Based on economic index and phenotype, 23 clones (italicized and bold in Table 1) were selected for further evaluation in experiment 2. These included 14 clones from the United States, five from China, and one each from Argentina, Colombia, India, and New Guinea.

The six most profitable clones in experiment 2 all had at least one CP parent (Table 2). Brown rust (caused by Syd.) was observed in 14 of 23 clones in the field. Rust is a disease with significant economic impact on sugarcane in Florida and is of particular concern for growers on mineral soils. 'LCP 85-384' and 'LCP 86-454' were notable for their high plant populations and low stalk weight, while the Yuetang clones exhibited the opposite growth pattern. Clones with US origins again had the highest sucrose contents on Florida mineral soils. The top ten sucrose concentration values were recorded for these clones. Four of the Yuetang clones were in the top ten in terms of cane yield; however, their low sucrose content reduced their economic index relative to CP clones. The seven clones selected for inclusion with commercial check 'CP 78-1628' in experiment 3 are italicized and bold in Table 2.

Genotypes included in experiment 3 (Table 3) were 'CP 68-350' (used in Texas and Argentina), 'CP 78-1628' (check, #1 Florida cultivar on sand), 'CP 73-1547' (check, previous #2 Florida cultivar on sand), 'LCP 85-384' (#1 cultivar in Louisiana), 'LCP 86-454' (Louisiana cultivar), 'TCP 88-3461' (promising genotype in Texas), 'US 90-0026' (borer-resistant) and 'TCP 87-3388' (early-sugar cultivar). 'CP 68-350' produced significantly greater tonnage than the LCP, TCP and US clones in both plant-cane and first-ratoon crops. 'TCP 87-3388' was notable for poor tonnage in both crops. The three CP clones selected in Florida ranked higher in tonnage, sucrose yield and economic index than the five foreign canes in both the plant-cane and first-ratoon crops. Rust was observed in the field on the three CP clones as well as on 'US 90-0026' and 'TCP 87-3388.' However, no rust was observed in any plot of 'LCP 85-384,' LCP 86-454,' and 'TCP 88-3461' during both experiments 2 and 3 (Tables 2 and 3). So, these clones could potentially be used as parental material in the CP breeding program to improve disease resistance.

Conclusion

The foreign cane cultivars tested were inferior to the CP clones for various yield parameters when grown on mineral soils of Florida. One possible explanation is that Florida mineral soils cropped to sugarcane are generally classified as Entisols or Spodosols with extremely high sand contents (> 90% sand) and low (< 3%) organic matter, whereas the foreign canes tested were selected in mineral soils with higher clay contents. Thus, increased selection efforts of CP germplasm on sandy soils may be a more effective strategy than testing of commercial foreign canes on sandland. However, foreign cane should continue to be imported for use as parental material in the basic breeding program to improve sugarcane biomass yields and disease resistance.

References

Deren, C.W., Alvarez, J. and Glaz, B. 1995. "Use of economic criteria for selecting clones in a sugarcane breeding program". Proc. Int. Soc. Sugar Cane Technol. 21: 437–447.

Edme, S.J., Miller, J.D., Glaz, B., Tai, P.Y.P., and Comstock, J.C. 2005. "Genetic contributions to yield gains in the Florida sugarcane industry across 33 years". Crop Sci. 45 (1): 92–97.

Gilbert, R.A., Shine Jr. J.M., Miller, J.D., Rice, R.W. and Rainbolt, C.R. 2006. "The effect of genotype, environment and time of harvest on sugarcane yields in Florida, USA". Field Crops Res. 95: 156–170.

VanWeelden, M. T., S. Swanson, W. Davidson, M. Baltazar and R. Rice. 2019. "Sugarcane variety census: Florida 2018". Sugar Journal. 82(2): 12–19.

Tables