KEY CHECK 6:
Avoided excessive water or
drought stress that could affect
the growth and yield of the crop.
- Adequate water supply facilitates land preparation especially leveling;
- ensures good crop establishment with faster root development;
- promotes seedling vigor and normal crop growth and development, with minimal lodging; and
- facilitates better nutrient uptake with the right amount and timing of water.
This corrects some nutrient imbalance problems and minimizes leaching.
- No symptoms of stress due to excessive water observed at vegetative stage i.e., reduced tillering and leaf area. Excessive water means water depth greater than 5 cm for 7 days or more.
- No symptoms of stress due to drought observed at vegetative stage, i.e., leaf rolling, leaf tip drying, reduced leaf area, height, and tiller number.
- No symptoms of stress due to drought observed from panicle initiation to grain filling, i.e., leaf rolling, leaf tip drying, reduced panicle exertion, and many unfilled grains.
For a 120-day variety, early panicle initiation is usually at 40-45 days after transplanting (DAT) or 61-65 days after sowing (DAS) and ripening phase is usually from 70-100 DAT or 91-120 DAS.
- Achieve 3-5 cm water depth every irrigation time from early tillering until 1-2 weeks before crop maturity or harvest.
A 3-5 cm water depth maintained from 10 DAT or 10-15 DAS to near crop maturity will ensure water status for optimum crop growth and yield. However, under field conditions, irrigation water supply may be insufficient to maintain a flooded soil condition or a certain surface water depth. While a certain flood water depth can control weeds, saturated soil condition at an early crop growth stage can reduce snail mobility and damage.
Controlled irrigation or Alternate Wetting and Drying (AWD) that does not induce plant water stress or reduce plant growth can be followed to use water efficiently. Under this system, water is allowed to decrease from 5 cm floodwater depth to 15 cm below the soil surface (perched water table) in dry season and 20 cm below the soil surface in wet season, before re-irrigating the field. This can be done from transplanting to maximum tillering. At heading or flowering stage, a floodwater depth of 3 to 5 cm is maintained.
To monitor the perched water table, a 30 cm perforated cylinder or bamboo or observation well can be installed in the soil up to 20 cm below the soil surface.
- Stop irrigation 1 week before harvesting for medium textured soil and 2 weeks for fine textured soil.
This ensures sufficient moisture to complete grain filling and facilitates harvest operations. This also helps ensure better grain appearance, i.e., grains will not be splashed with mud and water.