Origin and Breeding History of the Variety
M-104 is a very early, semidwarf, California glabrous, Calrose quality medium-grain experimental variety that has been evaluated in large plot yield tests since 1995 under experimental designation 95-Y-214. It is a very early selection from the 1990-1991 winter greenhouse cross R17135 and has the pedigree M-103//F1 (90-Y-275/M-103), thus the full pedigree is M-103/6/M-102/4/M201/3/M7/M9//M7/5/M-103. All varieties used in the pedigree were developed by the California Cooperative Rice Research Foundation (CCRRF) at the Rice Experiment Station (RES), Biggs, CA. They all are considered Calrose medium-grains with semidwarf height. 90-Y-275 was a very early experimental line and has the pedigree M-102/4/M201/3/M7/M9//M7. It was derived from the cross of a previous line (M201/3/M7/M9//M7) tested in statewide yield tests. The male F1 identified as R16618 was made in the 1990 summer greenhouse. Only M-103 is currently in commercial production in California. M-104 is the product of modified pedigree breeding. Very early spray painted panicle selections from the 1992 F2 nursery were bulked 6 panicles per row in the 1992-1993 Hawaiian nursery. Panicle selections grouped from the R17135 Hawaii rows were planted in 1993 individual rows. 93 row 63633 was identified as the source of 1994 small plot 83 which produced seed for 95-Y-214 RES Preliminary Yield Trial. It has been tested in the University of California Cooperative Extension (UCCE) Statewide Yield Tests from 1996 to 1999.
Selection and multiplication
M-104 selection was made for earliness of M-103 and for higher seed weight similar to other Calrose medium grains. Panicle selections were first taken for headrow production in 1996 and continued through 1999. The 1996 panicles were initially purified in the 1997 headrow nursery. The 1997 headrows were bulked to plant the breeder seed increase and headrow panicles selected for 200 headrows in 1998. The 1998 breeder seed was used to plant the 1999 foundation seed and the bulk of 1998 headrows planted the 1999 breeder production area. The 1998 head row panicle selections were used to plant 400 headrows in 1999.
Uniformity and stability
The breeder, foundation, and headrows were rogued multiple times and off-types, putative out crosses, and other visual variants were removed from the field. These included smooth, slightly later, taller medium grains, glabrous longer medium grains from possible outcrossing, elongated upper internodes, pubescent medium-grains and pubescent short grains in a total frequency of 0.02%.
Statement of Distinctiveness
M-104 is a semidwarf, very early maturing, medium-grain being released to serve the Calrose medium-grain market. “Calrose” was the founding California medium-grain rice variety, the ancestor of California medium-grains, and is now recognized as a market class term for California medium-grain rice. Comparisons for evaluation purposes were made to M-103 and M-202, which are similar quality types. M-104 has a heavier 1000 grain weight than M-103 and is earlier than M-202. M-104 is most similar to M-103 and can be distinguished by it’s higher brown rice kernel weight.