Rice Physiological Responses to Alternate Wetting and Drying (AWD) Water Management.

Declining availability of water and lack of rainfall is threatening the traditional way of growing rice under flooded conditions. Efficiency in the use of water is critical to safeguard food security especially of rice—the staple food for more than half of the world’s population. A study was conducted in the greenhouse at Texas A&M Agrilife Research Center at Beaumont, Texas to evaluate different water management systems for rice production. The U.S. rice cultivar ‘Cocodrie’ was grown in pots filled with a clay-rich soil, which were placed in boxes lined with plastic to hold the flood water surrounding the pots. Plants were grown under three water regimes: alternate wetting and drying (AWD), saturated or flooded soil conditions. Plant height, numbers of tillers and percent productive tillers, total grains per panicle, spikelet fertility, 500-grain weight; shoot, root, and grain dry weights; total biomass, chlorophyll concentration (SPAD), leaf photosynthetic rate and water input were determined. Our results indicate that plants grown under different water regime had similar numbers of tillers per plant; shoot, and grain dry weights; total biomass, and chlorophyll concentration. Plants grown under flooded soil condition were taller, had a higher percent of productive tillers, higher spikelet fertility, root dry weight, leaf photosynthetic rate, and water input than those under the AWD. Plants grown under the AWD condition showed higher 500-grain weight, whereas plants grown under saturated soil had a lower root dry weight. Depending upon the availability of water, rice can be grown under AWD or saturated or flooded condition. The best economic choice will be influenced not just by quantity of water used, but also by aspects such as grain size effects on quality, and other factors not studied here such as control of weeds, pests and diseases.