Varietal Development at RES-72



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Project Leader and Principal Investigators

M.D. Morse, California Cooperative Rice Research Foundation

H.L. Carnahan

J.J. Mastenbroek

S.T. Tseng


Short stature, extremely high yields, and greater stem strength for resistance to lodging are being incorporated successfully in new experimental strains. Selection has also been effective for heavy tillering and a change in leaf angle for better use of sunlight.

Some of the short-statured parents used in breeding had a very long maturity period, but lines were nevertheless developed that mature in 120 to 150 days.

In preliminary trials harvested by combine at Biggs, 34 new short-statured pearls of Colusa maturity yielded 87 to 105 hundredweight (average 93 cwt) at 14% moisture. That was an average yield increase of 31% over 71 cwt for Colusa in the trial. Of 36 short-statured early-maturing medium grains, the highest yield was 98 cwt at 14% moisture, and the average yield of the 8 highest was 90 cwt (compared with 77 cwt for the California check variety).

Yields at Biggs of the pearl and medium-grain short-statured varieties maturing slightly earlier than Calrose were only 7 to 10% above Calrose. A possible cause was leaf browning and blanking. Both are associated with the tropical parentage and induced by cool temperatures.

The short-statured plants appear adapted to water depths of 4 to 5 inches or less. It may be difficult to develop high-yielding short-statured plants able to emerge satisfactorily from deeper water, though the breeding program still has that goal.

Cooking quality is satisfactory, being typical of the present short-grain and medium-grain varieties. Grain appearance should be improved although some lines are comparable with present varieties.

Release of the new type must wait on additional selection and statewide testing. The best of the new plant types should be ready for seed increase within 5 years. Additional crossing and selection will improve the short types further.

Several high-yielding smooth-hulled pearls of Colusa maturity have been selected from the cross of Colusa with CS-M3. In statewide tests in the past 2 seasons, conducted by the UC Agricultural Extension Service, these lines have yielded 10-20% more than Colusa. In 1972, nine of these lines averaged 10% more than Colusa at 5 locations. The best averaged a 22% increase. The straw is stronger than Colusa's, though they are still subject to lodging. One is being increased for possible release to replace Colusa.

Tested at 3 locations were 2 early-maturing selections from CS-M3 that head 11 days earlier than the parent. In these preliminary tests the yield was satisfactory. In 1973 they will be included in statewide tests to verify their adaptation and to appraise milling quality. (RES1) (The preceding identification refers to a list of projects and personnel at the end of this report.)

Two selections from CS-S4 headed before Colusa and yielded well in tests at two locations. These smooth-hulled pearls will be included in the 1973 statewide tests.

Tests have shown that a long grain grown in California can have cooking quality similar to that of southern long grains. In the fall of 1972 a large number of selections were made from second-generation plants produced from crosses. Selections made from these crosses on the basis of growth, head size, grain shape, and freedom from blanking provide the basis for developing a commercial variety. Seedling vigor (with a few exceptions) is not up to present varieties, but development of these lines is still early and an effort is being made to improve this characteristic.

CS-S4, a smooth-hulled pearl variety was released in 1972, after averaging a 7% yield advantage over Caloro in 15 statewide Extension tests over a 6-year period. During 1972, seven yield tests were conducted by the Agricultural Extension Service and at the Rice Experiment Station. At all locations CS-S4 outyielded Caloro for an average yield increase of 7 cwt per acre.

CS-S4 and Caloro are similar in maturity and more susceptible to blanking than other varieties. Therefore, CS-S4 should be grown in areas that have proved suitable for Caloro, planted early, and not overfertilized with nitrogen. The smooth hull improves grain flowability, increases volume weight, and reduces dust in harvesting and milling.

High-protein rice is still sought despite some difficulty in combining that characteristic with high yields. Results of 1972 still await complete laboratory analysis. (RES 1)


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