The Texas AgriLIFE Research & Extension Center at Beaumont conducts extensive research on all aspects of rice breeding and production practices. Following are synopses of two such studies.
Dr. Lee Tarpley conducted the study on “Seeding rate of rice,” and Dr. Tarpley and Dr. Fugen Dou collaborated on “Rice management practices for stale seedbed vs. conventional tillage.” The Texas Rice Research Foundation supported both studies.
Seeding rate of rice
Because of the relatively high cost of seed for some varieties, interest in the effect of seeding rate on main crop yield has been revitalized. A study conducted by the Physiology Project at Beaumont in 2006 showed a strong increase in CL171 ratoon crop yield due to reduced planting density.
In 2007, the seeding rate study was conducted at Eagle Lake, using Cocodrie, CL171 and CL161. In each case, the main crop yield was significantly increased by the reduced seeding rate (40 lb/A) vs. the 70 lb/A rate. Also, the main crop grain moisture content and the ratoon grain moisture content were significantly greater at harvest for the lower seeding rates.
Results from 2008 and 2009 also indicated that planting Cocodrie, CL151, CL161 or CL171 at the reduced seeding rate of 40 lb/A vs. 70 lb/A did not reduce grain yield or milling quality. Plant height was essentially identical at the two planting densities.
The main crop grain moistures of the lower planting density averaged 0.5 percent higher at harvest, suggesting some delay of maturation and indicating some potential for additional yield (beyond the harvested yield) through increased growth duration or grain-filling duration at the lower seeding rates. Similar results also were seen for the rice variety Sierra.
The conclusion was that a reduced plant-ing density appears to be economically beneficial based on seed costs and yield.
Stale seedbed vs. conventional tillage
The use of stale seedbeds can help allow planting in the optimum window during wet years, can ease weed management and often increases yield relative to conventional tillage. However, stale seedbeds can affect nutrient management. In 2008 and 2009, a study was conducted to evaluate the effects of nutrient management practices on grain yield of Cocodrie in stale seedbed vs. conventional tillage.
Using the optimum planting date at Beaumont, Cocodrie was planted in stale seedbed plots (winter till) and in plots prepared using conventional tillage.
Total nitrogen (N) rates of 150, 180 and 220 lb/A were applied in two or three applications. An application of 50 lb/A phosphorus (P) was compared to no added P for each N rate and tillage.
Results from this study showed that the effects of tillage, N rate and P application were largely independent, and although significant and consistent, were not dramatic. In 2008, the conventional tillage treatment (7,745 lb/A) produced higher grain yield than the stale seedbed treatment (7,431 lb/A).
Plots not fertilized with phosphorus produced a higher yield than the 50 lb/A P treatment, with yields of 7,647 and 7,529 lb/A, respectively.
The 220 lb/A nitrogen treatment produced higher grain yields than the 180 lb/A nitrogen treatment, with yields of 7,872 and 7,632 lb/A, respectively. Both of these N rates produced higher grain yield than the 150 lb/A nitrogen rate, which yielded 7,260 lb/A. The 2009 results for tillage, N and P effects also were similar.
The conclusion of the study is that the economic cost or benefit of the particular treatments will probably outweigh the economics of yield advantage when developing stale seedbed management practices.
To see more research study results, go to beaumont.tamu.edu, eLibrary, 2009
Highlights in Research.