Morton Morse, director of the Rice Experiment Station, welcomes visitors to the annual field day at Biggs.

New Genetic Combinations

A total of 1,015 new crosses and the second generation lines from 917 previous crosses were grown on 28 acres in 1982. A few potential sources of resistance to sheath blight were introduced. About 100,000 rows were grown at Biggs, Davis, San Joaquin County and Hawaii for selection and purification. Four thousand small plots and 2,544 larger plots for combine harvesting were grown on the station for both preliminary and advanced yield and agronomic evaluations. Only the best of these are then tested in the statewide trials conducted on the station and by Cooperative Extension in growers' fields.

Lodging and Maturity

Only short-stature segregates are selected from crosses between tall and short parents. The reduced height is the primary basis for reduced lodging, but a stronger stem is a secondary characteristic of importance, even in short-statured lines. A full range of maturity classes is included in the breeding program. Progress is being made in combining high yield and good milling characteristics in very early lines. However, it is difficult to obtain high head yields in very early lines.

Quality

Quality characteristics of importance in the breeding program are grain size, plumpness, translucency, shape, breakage, and uniformity. Some 40,000 to 50,000 lines are selected annually for these characteristics from about 300,000 in initial selections.

Emphasis in the long grain breeding program is on physical and chemical characteristics of starch and on cooking quality. It is necessary to make crosses between Japonica types (for adaptation) and long grains (for quality) to obtain adapted long grains for California.

It is difficult to obtain high head yield from varieties that ripen when temperatures are high and humidity is low during grain filling. Readsorption of moisture after kernels are dry such as occurs in rain delayed harvest contributes to breakage during harvesting, shelling and milling. Selection for higher head yield continues to be an important objective, especially in early maturing and long grain lines.

Increase plot of a promising early maturing experimental selection at the Rice Experiment Station, Biggs.

Long Grains

The long grain variety L-201 continues to give high average yields, and its performance in the warmer areas of the state has been established. The limitations of L-201 are susceptibility to Ordram used at higher rates, lodging when grown at very high nitrogen fertility, and it does not cook as flaky as the Southern long grains.

In our 1982 trails, two experimental long grains gave excellent yields in warmer areas, are shorter than L-201, tolerant to Ordram and are 3 or 4 days later than L-201. One line in the early generation evaluation program not only has high yields and cold tolerance but has cooking characteristics similar to Southern long grains. It will be in the 1983 evaluation trials.

Sweet Rice (Glutinous)

A new superior sweet rice will be included in the 1983 evaluation trials. It is very early, maturing two days earlier than M-201, yielded 800 pounds higher than M9 and M-101 in trials at Biggs, and is superior to M-101 in blanking tolerance in our San Joaquin trial plots. Head yield may be a problem with a variety maturing this early.

Tolerance to Low Temperature

A severe test for resistance to blanking was obtained at a nursery in San Joaquin County in 1982. Several breeding lines representing all grain types showed 10 to 25 percent blanking compared to 40 to 50 percent blanking for presently grown ; varieties. These materials will be used as parents of crosses as well as advanced to the testing program.

In our 1982 trials, two experimental long grains gave excellent yields in warmer areas, are shorter than L-201, tolerant to Ordram and are 3 or 4 days later than L-201. One line in the early generation evaluation program not only has high yields and cold tolerance but has cooking characteristics similar to Southern long grains. It will be in the 1983 evaluation trials.

Resistance to Diseases and Tolerance to the Rice Water Weevil

The program initiated several years ago to transfer stem rot resistance from Oryza rufipogan to cultivated rice is proceeding on schedule and continues to hold promise. Sheath blight is increasing as a disease of importance in the nurseries and in field-grown rice. A continuing effort is being made to find better sources of resistance to include in the breeding program. Limited progress was made in 1982 in selecting for tolerance to the water weevil because of low weevil populations. Therefore, many lines were eliminated for other characteristics, and surviving lines will be re-entered in the 1983 selection nursery.

Herbicide Tolerance

A rapid laboratory test devised to select for tolerance of long grain lines to Bolero proved to be successful as checked by field trials in 1982. The laboratory test will continue to be used to select long grain lines that are tolerant. Lines resistant to Bolero also carry resistance to Ordram.

Seedling Vigor

Seedling vigor continues as a selection characteristic in the breeding program. Good progress has been made in seedling vigor and stand establishment of long grain lines of rice.

Table 1. Characteristics of Publicly Developed Rice Varieties-1983

Grain	Height*	Maturity	Seed widely available	Comments
Short
S-201	Short	Early	1981	Very high yield potential, replaced S6; more resistance to blanking than S6; maturity like S6.
Medium Grain
M-101	Short	Very Early	1981	Earliest variety; excellent seedling vigor; good resistance to blanking best suited for special conditions such as cold areas and/or late planting dates; head rice can be low, so harvest as near to 25% moisture as possible to enhance head yield. May not yield as well as other varieties at normal planting dates.
M9	Short	Early	1979	Very high yield potential in warmer areas; not adapted to colder areas or to very early seeding because of poor seedling vigor; mixed maturity of seeds on panicles. Somewhat difficult to thresh cleanly - special harvest adjustment may be necessary. May be more susceptible to sheath blight.
M-202	Short	Early	1984	Same maturity but with improved yield potential compared to M9; 2-3 inches shorter than M9 with greater resistance to lodging. Intended as a replacement for M9 in warmer 2/3 of state where M9 is grown. Threshes easier than M9.
M-302	Short	Intermediate	1983	Replaced M-301; has better straw strength; more translucent grains; is about 2 days later; has good seedling vigor and resistance to blanking. Can be seeded 7 or 8 days later than late varieties to spread harvest season.
M7	Short	Late	1979	High yield potential; good seedling vigor and resistance to blanking; very good straw strength.
Calrose 76	Short	Late	1979	High yield potential; good seedling vigor and resistance to blanking; rough hulls and leaves, long awns in warmer areas.
M-401	Short	Late	1983	Intended as a premium quality rice and not as a replacement for M7. Has high yield potential; 3 days earlier than M7 but lodges more and is more sensitive to blanking. Sensitive to early draining and over fertilization.
Long Grain
L-201**	Inter- mediate	Early	1981	Very high yield potential in warmer areas; not adapted to colder areas; injury by Ordram® has been observed at rates greater than 3 a.i. lbs/acre; threshes readily at low cylinder speeds. Harvest at moisture content as near to 25% as possible to enhance head yield; matures in 7 to 10 fewer days after heading than do short- or medium-grain varieties.
Sweet
Calmochi -202**	Short	Early	1983	A sweet rice replacing Calmochi-201. Similar to S-201 in growth characteristics but 2 days later. Has smaller seeds. Yield much greater and lodges less than Calmochi-201, but yield about 8% less than S-201.
* The varieties with short height have replaced rapidly the tall varieties. Proper management of the short-stature varieties to obtain high yield includes: (1) managing water depth and other factors to obtain a dense stand; (2) good weed control; (3) nitrogen fertilization of 20 to 40 units higher than has been used for tall varieties; and (4) draining as late as possible before harvest.
** L-201 and Calmochi varieties should not be grown unless arrangements have been made first with a marketing agency.
PREPARED BY THE CALIFORNIA COOPERATIVE RICE RESEARCH FOUNDATION AND THE UNIVERSITY OF CALIFORNIA COOPERATIVE EXTENSION