Backcross Breeding to Increase Fiber Strength of Cotton
- William Meredith
Three cycles of backcross breeding to increase fiber strength (T1) of cotton (Gossypium hirsutum L.) were studied at Stoneville, Miss. The objective was to measure the effectiveness of the backcross procedure for maintaining an adequate level of T1 and producing desirable combinations of yield and T1. The source of greater T1 was FTA 263-20 (FTA) and the recurrent parent was ‘Deltapine 16’ (DPL 16). In each cycle, 480 F2 plants were grown. In both BC1F2 and BC2F2, 24 plants were selected. In BC1F3 and BC2F3, 12 and four progeny respectively, were used to initiate the next cycle. From each of the four families descending from the four selected BC2F3 progenies, 12 of 120 BC3F2 plants were selected. In 1974, four sets of families were grown at two locations with two replications each. In each replication of each set, two entries of DPL 16, FTA, and BC1F5 and BC2F1 parents, and one entry of each of the 12 BC3F3 progenies were evaluated for lint yield, yield components, and fiber properties.
Mean T1's for DPL 16, FTA, BC1F5, BC2F4, and BC3F3 were 193, 230, 220, 211, and 216, respectively. Therefore, a satisfactory level of T1 was maintained by the backcross procedure. Assuming yield and T1 were uncorrelated, the observed average line yield of BC3F3 was 9.8% less than expected. The decrease in expected yield was partially caused by a lower than expected lint percentage. Significant variability in lint yield was detected among the four sets. The family with highest yield was only 5.3% less than expected and also had above average T1 (T1 = 217). These results suggest moderate success in developing desirable combinations of yield and T1 by the backcross procedure.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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