|Daroub, Samira - UNIVERSITY OF FLORIDA|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 9, 2004
Publication Date: September 1, 2004
Citation: Glaz, B.S., Morris, D.R., Daroub, S. 2004. Sugarcane photosynthesis, transpiration, and stomatal conductance due to flood and water table. Crop Science 44:1633-1641. Interpretive Summary: Sugarcane, the primary crop on the organic soils of the Everglades Agricultural Area in Florida is exposed to short-duration floods or undesirably high water tables due to decreasing soil depth and reduced-drainage practices that limit P discharge to the natural Everglades. In this study, photosynthesis responses of sugarcane to water-table depth and periodic floods were studied. The control treatment was a constant water-table depth of 50 cm. Rates of photosynthesis were often not reduced by floods or high water tables. When water table did affect photosynthesis rates, it was more likely that maximum rates occurred at 16 cm rather than at water-table depths of 33 or 50 cm. Previous studies have reported that high water tables and/or short-duration, intermittent floods do not reduce sugarcane yields. Results of this study provide a physiological explanation for these previous observations. Information from this study can be used to in future research to identify the highest water tables at which sugarcane can sustain yields, and the maximum flood duration that will not reduce sugarcane yields. As water tables are raised in the Everglades Agricultural Area, soil conservation efforts will improve and harmful export of phosphorus to the Everglades will be reduced.
Technical Abstract: Sugarcane (Saccharum spp.), the primary crop on the Histosols of the Everglades Agricultural Area (EAA), periodically is exposed to floods or undesirably high water tables. Improved understanding of the physiologic responses of sugarcane to these conditions could help develop strategies to sustain high yields. The purpose of this study was to evaluate the effects of periodic floods followed by drainage to different water-tables on single-leaf net photosynthetic rate (Ps), transpiration (Ts), and stomatal conductance (SC) of sugarcane. In 2000 and 2001, experiments were conducted outdoors in lysimeters filled with Pahokee muck soil. Two sugarcane genotypes were planted as split plots in three replications of four water treatments arranged in randomized complete block designs. During the summers, Ps, Ts, and SC rates were measured for four 21-day cycles. Each cycle included 7 days of flood followed by drainage for 14 days to 16, 33, and 50 cm. The fourth treatment was a continuous 50-cm water table. In one of two years, measured Ts and SC were maximum at a drained water-table depth of 16 cm and minimum at 33 cm. Otherwise, flooding for 7 day and draining to 16 cm often did not affect Ps, Ts, or SC, although rates were reduced in some cycles and increased (more often than reduced) in others. These results provide a physiological explanation for the reports of acceptable sugarcane yields under extended duration high water tables or short-duration floods. Further studies should aim to better understand the somewhat inconsistent responses of sugarcane Ps at water-tables ¿ 33 cm and to study sugarcane Ps at flood durations beyond 7 days.