Characterization of Rice



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Project Leader and Principal UC Investigators

James G. Fadel, Dept. of Animal Science, UC Davis

David J. MacKill, USDA, Dept. of Agronomy and Range Science, UC Davis

While growers are looking at different ways of disposing of rice residue in the field, this research project, in its second year, analyzed straw composition - information that may develop this "waste" into a potential resource.

The composition of 50 rice varieties was measured for a number of factors. Ash and fiber content ranged from 13.4 percent to 20.4 percent and 56.3 percent to 68.9 percent respectively. Lignin. ranged from 3 percent to 4.4 percent and silica ranged from 8.8 percent to 13.3 percent. Nitrogen ranged from 0.19 percent to 0.86 percent; fat ranged from 0.80 percent to 1.13 percent. The percentage of straw in the total plant biomass ranged from 31.2 percent to 63.9 percent This last measurement of straw provides data on the biomass of straw relative to grain among 50 varieties.

The high variability in the components of straw is a positive finding, since it gives geneticists a diverse pool of traits to select from. The baseline data being developed from this study is important for two reasons.

First, the composition of rice straw wiII affect its decomposition, knowledge that will prove useful in management decisions. In other words, it can give the grower an idea of how much straw must be removed or incorporated. Knowledge of the composition of rice straw will also become increasingly important as alternative uses develop. The components of straw will have some bearing, for instance, on its conversion to ethanol or combustion into energy. Second, this information can serve as the foundation for making breeding selections.

Also in development is a fermentation index, a relative measurement of straw breakdown in an anaerobic fermentation system. This information may provide relative comparison of the breakdown of straw after incorporation.

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