|MILLIGAN, SCOTT - Monsanto Biotechnology|
|HOLDER, DAVID - Us Sugar Corporation|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2001
Publication Date: 3/31/2002
Publication URL: http://hdl.handle.net/10113/11398
Citation: Glaz, B.S., Edme, S.J., Miller, J.D., Milligan, S.B., Holder, D.G. 2002.Sugarcane Cultivar Response to High Summer Water Tables in the Everglades. Agronomy Journal. 94:624-629.
Interpretive Summary: In the early 1990s, it was learned that undesired phosphorus export from the Everglades Agricultural Area (EAA) to the natural Florida Everglades was reduced by minimizing pumping from farms to public canals. Therefore, sugarcane, the primary crop in the EAA, began to be exposed to higher water tables (wetter conditions) as farmers under new best management practice (BMP) regulations began learning that they had to let excess rainwater subside from their fields more by evapotranspiration and seepage and less by pumping it to public canals. A potential advantage of this practice was that it could help improve soil conservation by reducing the aerobic microbial oxidation of the organic soils on which about 80% of Florida’s sugarcane is grown. At that time, it was assumed that the wetter conditions caused by these BMP regulations were reducing sugarcane yields. However, it was not known to what extent yields were reduced and whether some varieties might have been more tolerant than others to these wetter conditions. This field study, tested sucrose per acre yields of nine sugarcane varieties to two summer water tables that held the water closer to the soil surface (6 and 15 inches) than was conventionally done in commercial fields. The experiment included two plant-cane harvests, two first-ratoon harvests, and one second-ratoon harvest. The wetter field (water table 6 inches below the soil surface) caused a yield loss of 8.3% compared with the drier field (water table of 15 inches below the soil surface). However, sucrose per acre yields of varieties CP 72-2086 and CP 82-1172 were not affected by water table treatments and CP 85-1382 had higher sucrose yields on the wetter field. A major negative finding was that the most widely planted variety in Florida at that time, CP 80-1743, had a sucrose per acre yield loss of 25.1% due to the wetter treatment. These findings quantified potential yield reactions of nine sugarcane varieties due to BMP compliance for sugarcane farmers in Florida. This information added to farmers’ capabilities to strategize their BMP implementation by selecting which fields to hold at higher water tables for longer periods. For researchers, these findings identified a wide range of variability for tolerance to wetter conditions among commercial varieties in Florida which meant that to breed to improve for this trait, it would not be necessary to make wide crosses of sugarcane with some of its water-tolerant (but low sucrose) relatives.
Technical Abstract: Sugarcane (interspecific hybrids of Saccharum spp.) in the Everglades Agricultural Area (EAA) in Florida is frequently subjected to periods of higher than desired (wetter) water levels. This study was conducted to evaluate yields of nine sugarcane cultivars subjected to the wet conditions of two higher than conventional water tables in the EAA during the summer rainy season from the plant cane through the second ratoon annual crop cycles. Field experiments were planted in February 1997 and January 1998. During the summers from 1997 through 1999, we sought to maintain water = 15 cm below the soil surface (BSS) in the wetter field and from 15 to 38 cm BSS in the drier field. Water tables of commercial sugarcane fields in the EAA fluctuate from 40 to 95 cm BSS. Targeted water levels were achieved for 40 d in 1997, 104 d in 1998, and 96 d in 1999 in the wetter field and for 35 d in 1997, 96 d in 1998, and 82 d in 1999 in the drier field. The mean sucrose per hectare in the wetter field was 91.7% that of the drier field. Yields of cultivars CP 72-2086 and CP 82-1172 were not affected by water table. Cultivar CP 85-1308 had higher yields in the wetter field in two of five harvests. Sucrose per hectare of CP 80-1743 was reduced by 25.1% in the wetter field. The variable sucrose per hectare yields among these nine commercial sugarcane cultivars suggests that routine screening of promising sugarcane genotypes under high water tables would help identify more cultivars that maintain high yields in wetter conditions in the EAA.