|Lingle, Sarah -|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 14, 2011
Publication Date: February 16, 2012
Repository URL: http://handle.nal.usda.gov/10113/56505
Citation: Glaz, B.S., Lingle, S.E. 2012. Flood Duration and Time of Flood Onset Effects on Recently Planted Sugarcane. Agronomy Journal. 104:575-583. Interpretive Summary: Undesired phosphorus export from the Everglades Agricultural Area (EAA) to the natural Florida Everglades is reduced by minimizing pumping from farms to public canals. Therefore, sugarcane, the primary crop in the EAA, is exposed to high water tables and floods because farmers often try to let excess rainwater subside from their fields by evapotranspiration and seepage rather than by pumping it to public canals. This practice also helps improve soil conservation by reducing the aerobic microbial oxidation of the organic soils on which about 80% of Florida’s sugarcane is grown. Research has shown that repeated flooding durations of up to 2 weeks do not reduce sugarcane yields if these floods are drained to a depth of at least 40 cm for at least 1 week and if flooding occurs after June when the sugarcane has begun tillering profusely. However, Florida sugarcane growers are concerned that yields are reduced when flooding occurs before June on recently planted or recently ratooned sugarcane. This study, which included three pot experiments, tested biomass responses of two sugarcane varieties, CP 89-2143 and CP 96-1252, to flood durations of 0-6 weeks and flood onsets at 2 and 4 weeks after the recently planted sugarcane had reached a height of 9 cm. In addition, a second flood onset from 4-6 weeks prior to harvesting was also tested in each experiment. When not flooded, pots were drained to a depth of 30 cm below the soil surface. Experiments were stopped and leaf, root, and stalk weights were measured about 10 weeks after pots were planted. Leaf, stalk, and root weights were all reduced by flooding, and the longer the flood duration, from 0 to 6 weeks, the greater the reductions. Stalk and leaf weights of CP 89-2143 were more detrimentally affected by flooding than CP 96-1252, but root weights of CP 96-1252 were reduced by flooding more than root weights of CP 89-2143. Flooding was similarly detrimental to stalk and root biomass for flood onsets of 2 and 4 weeks after plants had reached a height of 9 cm. However, the flood onset of 2 weeks was more detrimental to leaf biomass than the flood onset of 4 weeks. These findings indicate that while sugarcane farmers in Florida are able to reduce phosphorus export to the natural Everglades by allowing short-duration floods of their sugarcane after June, they need to be aware that similar flooding practices on recently planted sugarcane (and perhaps recently ratooned sugarcane) prior to June may cause substantial yield losses. Follow up studies are now needed to determine if sugarcane that is flooded prior to June can still yield well by compensating with increased growth after June and prior to being harvested between October and April.
Technical Abstract: Periodically flooding sugarcane (Saccharum spp.) in the Everglades Agricultural Area (EAA) of Florida improves soil conservation and reduces P discharge to the Everglades, but farmers are concerned that flooding recently planted or recently ratooned sugarcane reduces yields. The purpose of this study was to determine the effects of time of flood onset and flood duration on stalk, leaf, and root biomass accretion of two recently planted (plant height ˜ 9 cm) sugarcane cultivars. In three pot experiments, flood durations ranged from 0-6 wk and flood onsets were after 2 or 4 wk at a 30-cm water-table depth. Five treatments also had a second flood onset during the final 4 or 6 wk of each experiment. Increased flood durations often resulted in declines in biomass explained by linear or quadratic models. Compared with ‘CP 89-2143’, leaf and stalk biomasses of ‘CP 96-1252’ were more tolerant of increasing flood durations, but the opposite was true for root biomass. Sugarcane leaf biomass was reduced more by flood onset following 2 rather than 4 wk at a 30-cm water-table depth, but stalk and root biomasses were similarly reduced by both flood onsets. Although previous results have indicated that well established sugarcane in its grand-growth phase is tolerant to periodic flooding, our results suggest that biomass of younger (recently planted) sugarcane is increasingly reduced by flood durations of 0-6 wk and that flood onsets after 2 or 4 wk at a 30-cm water-table depth are similarly detrimental.