Rice water depth management at microspore

Summary

The microspore stage in rice is when the pollen cells start to form in the anthers. Low temperatures at this stage disrupt the movement of sugars into the microspores, reducing the number of viable pollen grains produced, leading to floret sterility.

Microspore occurs in the middle of the reproductive period, about 16–18 days after panicle initiation (PI) and 12–14 days before flowering. It normally takes 2–3 days for a panicle to complete microspore but 7 days or more for a field, due to plant and crop variability.

Deep water provides a buffer from the low morning air temperatures because the water temperature decreases more slowly than the air temperature. The buffer created by the ponded water can raise the temperature around the panicle up to 7 °C above the air temperature in the crop, but the buffer effect does not extend far above the water surface.

Topics include:

• deep water provides a buffer against cold temperatures
• how deep should deep water be?
• what is the ideal time to apply deep water?