The Rice Extension organisation has issued an alert for cold temperatures on Sunday night, meaning rice growers will need to increase their water levels to 25 centimetres to avoid cold temperature damage. 

Cold temperatures at critical times during the reproductive period can cause large reductions in rice grain yield.

Sunday’s overnight temperature forecast is expected to drop to 10 degrees, while Monday night’s low will be 12 and Tuesday’s 14. 

At microspore, air temperatures less than 15 to 17 degrees can damage the developing pollen, leading to floret sterility and yield loss.

This damage is commonly referred to as cold induced sterility or flatheads.

Deep water (25 cm) is a very effective management tool in minimising damage caused by low temperatures and can provide up to 9 degrees increase over the air temperature.

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Growers have been urged to start increasing water depth once PI has been identified and maintain a 25cm depth until mid-flowering.

Deep water during late tillering and PI makes the rice plants taller and reduces the benefit of deep water at microspore.