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December 27, 1999
China's Winter Wheat Eludes Cold Weather Damage
China’s 2000/2001 winter wheat crop was planted between late-September and November. Timely rain in October and warmer than normal autumn temperatures resulted in fairly good germination and tillering, with the result that in early December the crop was entering dormancy in good condition. Temperatures started dropping rapidly after December 15 and reached their lowest levels on December 20 and 21. Minimum temperatures dipped below 0o C as far south as Guangdong Province, and below 5o C in the province south of the Yangtze River. North of the Yangtze, minimum temperatures ranged from -6o to -14o C before gradually rising again.
Although snow cover was very light or non-existent on the North China Plain, these low temperatures were well above the threshold for winterkill for dormant crops and caused no damage to winter wheat. No serious damage to the crop has been reported by trade or government sources in China.
The 7 to 10 day outlook calls for warmer (but still below-normal) temperatures and some isolated snow in northern and northeastern North China Plain.
Eastern Asia, Extreme Minimum Temperature (oC)
December 12-18, 1999
Background:
The USDA estimate for China’s 1999/2000 wheat crop is 115.0 million tons, up about 5 million from the previous year. Area is estimated at 29.0 million hectares, down 770,000 from the 1998/99 harvest. According to FAS/Beijing, official and non-official sources both indicate that winter wheat plantings for the 2000 crop are down as much as 5 percent, due in part to lower anticipated prices (GAIN report CH9066, 12/7/99). The Chinese Government allowed procurement prices to fall by about 12 percent in 1999, reducing farmers’ profits. Another possible reason for lower planted area is low water supplies for irrigation.
The first official USDA estimate for China’s 2000/2001 wheat crop will be published in May.
Winterkill Rules-of-Thumb
Winter grains need as least 2 mm of topsoil moisture to germinate. More rain is needed within 14 days of planting to flourish. Plant death due to dry weather after germination can sometimes be misinterpreted as winterkill. Gradual "hardening" will protect against winterkill. Optimal conditions for hardening are 5 to 6 days with average temperatures between 0o and 6o C. Plants which have completed the hardening process can withstand temperatures as low as -10o to -12o C. Dormancy happens when there are 2 to 5 days with average temperatures between -2o and -5o C. Once dormant, winter grains can withstand temperatures down to -17o C.
(See the November 9 winter planting assessment.)
For more information, contact Paulette Sandene with the Production Estimates and Crop Assessment Division on (202) 690-0137.
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