Submitted to: Proceedings of Southern Weed Science Society
Publication Type: Abstract Only
Publication Acceptance Date: 1/23/2017
Publication Date: 1/23/2017
Citation: Gealy, D.R., Rohila, J.S. 2017. EFFECT OF ALTERNATING WETTING AND DRYING IRRIGATION METHODS ON PHOTOSYNTHESIS AND TEMPERATURE OF RICE AND WEED PLANTS. Proceedings of Southern Weed Science Society. Birmingham, AL, January 23-26, 2017.
Technical Abstract: Reduced input systems such as alternating wetting and drying (AWD) and furrow irrigation can potentially reduce water costs and limit the release of greenhouse gases in rice production, but also can introduce unwanted crop stresses that compromise crop yield and quality, as well as introducing complications to weed management. This research investigated the effect of AWD practices on key plant productivity parameters such as leaf net photosynthesis (Pn) and canopy temperature (as measured using CI-340 or Li 6800 portable infrared gas analyzers), and grain yield. Field plot experiments were established in 2014-2016 to compare crop and weed performance in AWD and conventionally irrigated systems. Rice was drill-seeded in both systems and plots were maintained identically until application of a conventional permanent flood. All plots were flushed as necessary to maintain healthy rice growth after emergence. Beginning with the application of the permanent flood, conventional plots were maintained fully flooded by periodic reflooding to a depth of 10 cm until all plots were drained at the end of the crop season. By contrast, water levels under AWD irrigation typically were allowed to drop until the soil (silt loam) surface in plots was exposed and had dried to the point of crusting and moderate cracking, but before leaves began curling. Irrigation water was then applied to the AWD plots to a depth of 10 cm. At the time of the greatest potential for crop stress, just prior to reflooding, the canopy temperatures in AWD plots were 0.5 to 2 C greater, and leaf Pn levels in rice and red rice were 10-20% less compared with these parameters under conventional irrigation. AWD typically reduced rice yields 10% or less. These results indicate that Pn rates and canopy temperatures can provide sensitive indications of early stages of stress in rice plants, and might be useful in optimizing the timing of reflooding and in gauging crop recovery from AWD stresses.