Narrative
Early heading mutants at the mat-b locus show a rather drastic increase in earliness (heading 7 days earlier than their parental cultivars) under field cultivation in Sweden. When grown under controlled environmental conditions, mutants are photo- and thermoperiod sensitive and are classified as a pronounced long-day type. Early heading is also associated with decreased culm length, kernels per spike, and grain yield. They are generally more productive in field trials than mat-a (eam8) mutants, but less resistant to lodging, partially due to a modified culm structure. Compared with the original cultivars, they have one internode less per culm, a longer first internode, and a short basal internode. At an early stage of development, mat-b mutants are characterized by pale green color when grown at 15 to 20 degrees C, but they are bright green in color at lower temperatures. Inheritance: Monofactorial recessive. Location is unknown. Previous nomenclature and gene symbolization: Early 7=ea-b7. Early maturity-b=ea-b. Mutational events: mat-b.7, -b.10 (trans), -b.13 in Bonus; mat-b.34, -b.35, -b.38, -b.66 in Bonus, -b.106, -b.108, -b.134, -b.137, -b.145, -b.214, -b.216, -b.237, -b.244, -b.261, -b.279, -b.286, -b.313, -b.337, -b.403 in Foma (CIho 11333), -b.852, -b.853, -b.855, -b.859, -b.861, -b.867, -b.869, -b.870, -b.871, -b.904, -b.920, -b.922 in Bonus, -b.963, -b.977, -b.980, -b.986, -b.991, -b.992, -b.1008 in Sv 79353, -b.1082 in Sv Vg74233, -b.1103 in Sv Semira (NSL 206731), -b.1110, -b.1112, -b.1116 in Sv Frida; mat-b.1401 in Bonus; mat-b.1404, -b.1405 in Bonus. Mutant used for description and seed stocks: mat-b.7 in Bonus (GSHO 1788); mat-b.7 in Bowman (PI 483237)*3 (GSHO 2282).