Keith Fontenot | 3/18/2005 9:57:24 PM
We are at the beginning of our rice planting season. Rice yields may be reduced by planting too early and also by planting too late in the growing season.
Average daily temperature at seeding is crucial in stand establishment, and is arrived at by adding the daily high and low temperatures and dividing by 2. This gives an average Degree Day Temperature. Many of our producers use the DD50 Program in managing rice crops. This program is based on more than 30 years of weather data processed through computer simulation. This program is used to predict certain dates that coincide with growth stages of the rice plant and the associated management practice that should be performed at different growth stages.
The reason this program is called DD50 is that, at or below 50 degrees F, little or no rice seed germination will occur. From 50 to 55 degrees F, germination of the seed increases, but not to any great extent until temperature is above 60 degrees F. Plant survival is not very satisfactory until the average daily temperature is above the 65-degree mark.
Based on this temperature information and also on seeding date studies conducted at the Rice Research Station, recommended planting dates for rice are:
Figure 1 shows two charts depicting yield differences associated with date of planting for long grain and medium grain varieties. This study was conducted by Dr. Steve Linscombe in 2000-2003. The following dates are shown on the charts:
As the charts depict, the opportunity for maximum yields decrease after mid-April. Of course, many other factors come into play when planning seeding dates. This information does give excellent information on yield drop caused by planting date.
If rice is planted extremely early, you could run into: 1) slow emergence, poor growth, lack of seedling vigor due to cool weather, 2) increased seedling disease damage, such as water mold, 3) increased bird predation, blackbird, ducks and geese.
If planted too late: 1) yield potential decreases as shown above in charts, 2) panicle blight problems associated with high temperatures during pollination and grain fill, 3) increased potential for disease and insect problems, 4) decrease in grain quality, 5) ratoon crop timing. For an adequate growth period for second crop, the first crop should be harvested by mid-August.
Rice planted by April 15 for Southwest Louisiana has the most potential for good second crop, providing other selection factors for second crop are present.
For more information, contact Keith Fontenot at (337) 363-5646.