Hot weather may lower rice milling yields Rice milling yields may have taken a beating from the hot weather in August, says Chuck Wilson, rice specialist with the Cooperative Extension Service, University of Arkansas.
"The 85-degree nights are harder on the crop than the 110-degree days," said Wilson, who is at the Southeast Research and Extension Center at Monticello, Ark. "What happens is that, in the day, photosynthesis generates carbohydrates for grain filling and energy. The plants also use carbohydrates for respiration, needed for metabolic functions."
However, if night-time temperatures are high, plants have to use all of their energy for respiration instead of grain filling. This can result in smaller heads or blanks (hulls without grain).
If farmers see negative consequences from the weather, Wilson said, it will probably be in lower milling yields.
A break in the weather, such as Arkansas experienced in early September, can help offset this problem.
Wilson said the August heat may have interfered with pollination. "With fields that are flowering in this heat, you're likely to see a lot of increased blanks," Wilson said.
Farmers began harvesting earlier this month and some will likely wrap up harvest at the end of October. "I've heard a few early yield reports that were fairly decent, from 130 to 200 bushels an acre," said Wilson. "Earlier planted rice that was filling grain in early August may be better than the rice that was filling grain during the extreme heat. Farmers won't really know how bad it's gonna be until they harvest."
Meanwhile, the 100-degree weather challenged farmers to keep rice fields flooded. "It's harder to irrigate in a hot, dry year because of evaporation from the field and water loss from plants. Rice plants use water as a cooling mechanism among other things. They use more when it's hot and dry."
Often farmers try to keep rice and another crop such as soybeans irrigated. Sometimes neither crop gets enough water because farmers are struggling to irrigate a lot of acreage with a limited amount of water, Wilson said.
Farmers weren't helped by the fact that the winter was dry and aquifers didn't recharge from last year's high water usage. "We began the planting season with below-normal water supplies," Wilson said.
He said poor water management hurts all varieties, but some varieties such as LaGrue and Wells are more susceptible to rice blast disease when adequate flood isn't maintained. Farmers were hit this year by the double whammy of hot, dry weather and higher fuel costs, which affected diesel irrigation pumps. Fuel costs increased dramatically around planting time.
Wilson said a number of rice farmers have taken advantage of multiple-inlet irrigation, a system promoted by Phil Tacker, an Extension irrigation specialist. In many cases, farmers are conserving water and reducing labor during the growing season, Wilson said.
"The only negative complaint I've heard is it's harder to flush fields early in the season prior to flooding," Wilson said.
If there's a bright spot with the hot, dry weather, it's that disease pressure, particularly rotten neck from rice blast, has decreased. "There's been some sheath blight and a little blast, but it has been relatively light," Wilson said. Other diseases have been a problem in parts of the state, including false smut and panicle blight.