Registration of Tamcot SP37H Cotton (Reg. No. 75).

TAMCOT SP37H* cotton (Gossypium hirsutum L.) was developed in the Texas A&M Multi-Adversity Resistance (TAMMAR) program of the Texas Agricultural Experiment Station and was released in October 1977. The new cultivar was developed from parent strains of the Tamcot SP21 (Reg. No. 61) and Tamcot SP37 (Reg. No. 63) families (2, 6). The cross (66N, B.V.65), x (520.B.V.65), was made and individual plant selection began in the F1 of the single cross. Individual plant selection was based on seed coat resistance to mold and a reduced rate of germination when held for 8 days on 1.5% water agar at 13.3 C. This was followed by selection for seedling cotyledon resistance to a mixed inoculum of races 1, 2, 7, and 14 of the bacterial blight pathogen [Xanthomonas malvacearum (E. F. Sm.) Dowson]. Selecting to the F7 gave strains H2-45-74, W46-74, and HM7-74. Tamcot SP37H is a composite of these strains and was evaluated under the name TX-CAMD-H. The described levels of resistance used for representing relative differences with respect to departure from a susceptible type have been given (4).