Head Rice Improvement-89



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Project Leader and Principal UC Investigators

Shu Geng, professor, Department of Agronomy and Range Science, University of California, Davis


How to improve the quality and quantity of head rice-and hence grower profitability-is the focus of research in this area. Much of the work during 1989 centered around development of a comprehensive computer system with practical field applications. Field experiments sought to identify how well certain traits affecting head rice yield were passed on generation to generation.

Computer program advances

"Tests determined the precision and accuracy of the (computer) system to be excellent."

Researchers report important advances in an automated computer system that analyzes rice kernel size and weight. The system combines the expert "CALEX" computer system (a similar one is used by cotton growers), information from the UC Integrated Pest Management rice manual, the head rice computer program and the California rice phenology model.

The program performs four basic functions:

  • To provide general descriptions and recommendations to manage rice weeds.
  • To determine the optimal harvesting moisture level to maximize head rice yield.
  • To estimate the yield from a rice phenology model for a given set of weather conditions.
  • To perform an economic analysis based on the yield and the moisture content at harvest.

A prototype of this system has been developed. Its physical components consist of a vibrating bowl kernel separator, a kernel processing module and an IBM XT computer with a 20 megabyte hard disk. Kernels are separated by weight, length, width and thickness. A computer image is then generated by these measurements. Tests determined the precision and accuracy of the system to be excellent.

Field Experiments

In field experiments conducted at UC Davis, the researchers examined the heritability of a number of characteristics affecting head rice yield. They compared short, medium and long grain varieties under two different nitrogen fertilization regimes on different harvest dates.

While their analysis was not yet complete as this report was written, the researchers did notice the following noteworthy trends:

  • Panicle length is highly inheritable.
  • Seed length, breadth and width are moderately heritable, with little variation between lines of each grain type.
  • Environmental factors, such as cold water or cool night air temperatures, determines the number of blanks per panicle, especially in the long grains.
  • Soil nitrogen seems to influence head rice yield, also affecting tillering, number of panicles and seed characteristics.

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