Chairman's report - 96


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Rice Research Board Chairman, Stevve Dennis


Chairman.jpg (8257 bytes)The year 1996 brought the California rice industry a mixed bag of significant developments. The good: progress in the hunt for stem rot resistance and promising new chemicals to deal with rice weeds and the rice water weevil. The bad: rice acreage increased but rice yields continued to slip. The ugly: the discovery of rice blast, the most serious fungal disease of rice in the world. These and other developments are addressed in detail in the pages of this, the 28th annual report to the California Rice Growers. Although favorable market conditions in 1996 boosted rice acreage to 500,000 acres, a 35,000- acre increase over 1995, the estimated average yield continued a downward slide to 7,490 pounds/ acre. That compares with 7,600 pounds/acre in 1995 and 8,500 pounds/acre in 1994. The recent decline in yields underscores the need for a strong rice breeding program to stabilize yields.

In the Rice Breeding Program section of this report you will read about how scientists at the Rice Experiment Station (RES) are preparing to release next year M-205, an early maturing, smooth, large-seeded and high-yielding Calrose quality rice. These researchers already have a full plate of plant breeding objectives - stem rot resistance, cold tolerance, seedling vigor, improved milling yields and high yield potential, to name a few. The news late last season that rice blast had been discovered for the first time in California adds an essential new objective: resistance to this potentially devastating new threat. RES scientists have initiated a comprehensive search for single and multiple gene sources of blast resistance. And an aggressive monitoring program is in place for the 1997 season.

The future, it appears, is catching up with us fast. RES scientists also report on transgenic rice. Although a study at the Rice Experiment Station confirms the plausibility of genetically engineered herbicide resistance, obstacles to its commercial use in California need to be overcome. It's one thing to insert a gene into a rice plant; it's quite another to

develop one that performs up to the agronomic quality and consumer standards the California rice industry has come to expect. It will be at least a few years yet before transgenic rice meets these standards and legal issues concerning its use are resolved.

There is good news in the Genetics section of this report. Significant progress has been made in attempts to identify stem rot resistance. In 1996 geneticists identified several different 'molecular markers' associated with stem rot resistance. This greatly improves the chances of making a successful transfer of this important trait into California medium grains. Scientists also report on "dramatic" tests illustrating the power of an important gene involved in seedling vigor and important developments on hybrid rice production.

In a related study scientists sought to improve their understanding of the mechanisms of seedling vigor. Reported in the section Seedling Vigor, this research revealed several biochemical changes common to the seedlings of various submergence-tolerant rice cultivars. Researchers are very encouraged by initial results and plan to pursue the project in hopes of establishing the submergence tolerance trait in California rice varieties.

In the Variety Trails section researchers report on how advanced experimental lines are faring in statewide tests. Although several advanced and preliminary breeding lines showed some improvement in yield or other agronomic characteristics last year, most were at or below existing commercial varieties. Researchers say this demonstrates the difficulty in achieving greater yield advances. M-202, for example, was the highest yielding variety in the very early test and six of the top 10 yielding entries in the early test were commercial varieties. This project also examined the relationship between rice straw removal and potassium fertility; different nitrogen rates on Japanese varieties; the effect of varying nitrogen and potassium rates on disease incidence; and the effect of straw management alternatives on rice production.

Weed scientists are exploring new herbicides and reexamining old ones to fill the large void left in the wake of Londax®’s waning effectiveness. In the section Weed Control, researchers report on a promising new chemical scheduled for registration within two years; results from studies reexamining older herbicides; a project analyzing aerial drift; and a study confirming fears of watergrass resistance to several common herbicides.

Most research into Invertebrate Pests is directed toward control of rice water weevil, a pest that may be on the increase. A total of 5,420 weevils were captured at the RES during 1996 - 30 times more than that caught just five years ago. The flight was also much earlier and much longer - from April 5 to June 6 - than in previous years. Entomologists report favorable results from tests conducted on three insecticides that are moving toward registration - good news with the loss of Furadan for RWW control.

Knowledge of what happens to rice pesticides in soil and water is critical to decisions made about their management and regulation. In the section Environmental Fate of Rice Pesticides, toxicologists report on studies of Fipronil, one of the insecticides slated for RWW control. In contrast to prior reports that threatened the registration of Fipronil, a carefully constructed laboratory test showed that a chemical byproduct is persistent but degradable, with a half-life of 5.6 days under controlled laboratory conditions and as short as one day in the field. This information should substantially assist registration of Fipronil for use on rice.

Environmental toxicologists previously reported on the relatively high levels of copper in rice fields treated repeatedly with copper sulfate or "bluestone." Growers use the material to control algae and tadpole shrimp. Experimental chemical treatments to remove copper from rice fields were not encouraging, so toxicologists suggest rice growers consider using the water-soluble and biodegradable aquatic herbicide endothal as part of a copper management strategy.

In a separate toxicological study, researchers continued their examination of molinate. Since this herbicide has been shown to cause toxicity in rats, concerns have been raised about its potential threat to humans. However, research reported in Molinate Toxicity shows that different metabolic pathways are at work in humans and rats and that may account for different toxicological responses. This study showed that at low dose levels humans form less of the sulfoxide compound leading to toxicity than rats.

Until recently most of the work on Rice Diseases focused on control of stem rot and aggregate sheath spot. That all changed with the discovery of rice blast in the northern Sacramento Valley in early September last year. A hitherto unknown disease in California, blast causes considerable damage and yield loss throughout the world. If it were to become established here, blast could easily have a significant impact on the future of rice production in the state. Plant pathologists directed efforts to determine the extent of the blast infection and the susceptibility of California cultivars. Pathologists are continuing study of the blast disease in an effort to develop a logical industry approach to eliminate possible spread of the disease.

Another rice disease project is continuing on the effect of alternative residue management practices on stem rot and aggregate sheath spot. These scientists are also working on methods of predicting disease severity - techniques that will become crucial for growers requiring special burn permits where disease loss threatens. And more than a dozen promising sources of genetic resistance to both stem rot and aggregate sheath spot have been identified from the USDA rice germplasm collection.

Irrigation practices that have helped to curtail herbicide runoff into the Sacramento River may be creating salinity problems for some California rice growers. In the section on Salinity in Rice Production, scientists report on a survey that produced "strong evidence" salinity is reducing rice yields in several locations. While decreasing pesticide concentrations in tailwater runoff, new irrigation practices - static flow and recirculating systems - are apparently increasing the potential for field salinization by allowing salts to concentrate in lower basins. Salinity thresholds for rice grown in the Sacramento Valley may need to be adjusted and future water policy decisions would need to take this into account.

Research that will lead to new rice products for domestic and foreign markets is the work of scientists at the USDA’s Western Regional Research Center in Albany. In the section Rice Utilization and Product Development you will read about food scientists' work on the textural properties of rice, probably the single most important characteristic of the milled rice kernel. Much of their work has concentrated on developing more accurate instrumental and human sensory methods to understand the starch characteristics of rice as they relate to textural and functional properties.

The phasedown in rice straw burning continues to make residue management challenging for many growers. Nonetheless, in the section Rice Straw Burning Program you will read how favorable meteorological conditions allowed growers to burn substantially more acreage than in the three previous seasons. Complaints to the Air Resources Board dropped to the lowest level since 1989.

That's a quick look at some of the highlights from this, the 28th annual report to the California Rice Growers. I encourage you to take a little time to learn more about your investment in the future of the California rice industry through the Rice Research Board. Through our ongoing commitment to scientific research we can confidently greet the significant challenges and exciting opportunities that await us

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