Rice Genetics - 72



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Project Leader and Principal UC Investigators

M.L. Peterson, J.N. Rutger, Genetics, Breeding, Physiology and Varietal Evaluation

M.D. Davis

D. Jones

Lin Shiao Shong

Kenneth Taggard

D. HilleRisLambers

C.H. Hu

W.F. Lehman, Introduction of Rice Germplasm from Foreign Rice Programs into the United States

J.N. Rutger

R.W. Breidenbach, J.N. Rutger, Physiological and Genetic Determinants of Yield and Quality of Rice


Much of the research on rice at Davis on rice genetics and physiology concentrates on basics useful to breeding. Emphasis is placed on plant characteristics that affect yield and quality. So that proper attention is given the environment, genetic lines are being identified that are less affected by fluctuations in environment and therefore will be more stable in yields from place to place and year to year.


Yields may be cut more than 12% by empty kernels at harvest; some fields show over 25% empty kernels! The cause is low night temperatures (low 50's Fahrenheit) for 2-3 weeks just before heading. Varieties differ in resistance, so varieties with lower sterility should be possible.

Losses can also be reduced by: 1) planting earlier and using earlier varieties; 2) avoiding maturity delay from excess nitrogen fertilization; and 3) using deeper water in the 2-to-3-week period just before heading. Rice panicles at this sensitive stage, still enclosed in the stem, should be partly below water level, which has a minimum temperature about 10F warmer than minimum air temperatures.

Irradiating Calrose rice seeds to produce mutations has produced four short-stature and two early Calrose lines. Three of the short-stature lines are 10 inches shorter than Calrose, and the other is about 6 inches shorter. One of the two earlier lines is 15 days earlier than Calrose, and the other 5 days earlier. The best of these mutants equaled Calrose in yield in 1972. Their quality characteristics are not yet determined. Seed has been produced for yield trials at 3 locations in 1973. Mutation breeding may be a fast way of shortening present varieties without interfering with desirable characteristics.


Better sources now available for breeding high-protein rice avoid the poorer yields and other objectionable traits of most high-protein varieties. Now being purified for yield tests are selections with 30% more protein than California varieties.


A test method developed in Agronomy and Range Science at Davis has screened over 300 promising lines for seedling vigor and cold tolerance. A number of new sources of cold tolerance have been found. (RB3, RB4, RB5)


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