Combining Ability for Agronomic and Fiber Properties in Cotton Stocks Resistant to Pink Bollworm1
- F. D. Wilson and
- B. W. George2
Twelve agronomic and fiber properties were studied in six cotton parents (Gossypium hirsutum L.) and their hybrid and reciprocal combinations in 1977 and 1978 in insecticide-free environments at Tempe Ariz. Two parents, ‘Deltapine 61’ (DPL-61) and ‘Stoneville 256’ (St 256), are commercial cultivars and the other four are race and breeding stocks selected for resistance to pink bollworm (PBW), Pectinophora gossypiella (Saunders), in earlier tests. One race stock, Texas 167 (T-167), was similar in all 12 characters with at least one cultivar.
Significant general combining ability (GCA) estimates for most characters suggested that transferring resistance to PBW from T-167 to a cultivar should pose no formidable breeding problems. Significant specific combining ability (SCA) estimates were few and probably of little consequence except perhaps for lint yield in DPL-61 ✕ T-167 in 1977.
A resistant Upland breeding stock, AET-5, did not perform as well in relation to the cultivars as T-167 in 1977 when seed damage from PBW was low, but performed better in 1978, when damage was much higher. Results of the diallel analysis suggest that AET-5 will be more difficult to handle than T-167 as a breeding stock. Apparently, the mechanisms of resistance in T-167 and AET-5 are different. It may be possible to extract a segregate from T-167 ✕ AET-5 hybrids with enhanced resistance, but probably not with agronomic and fiber properties equal to those of the cultivars. The best use for such segregates would be as sources of PBW resistance to be incorporated into superior germplasm. The other two race stocks, T-31 and T-55, were inferior to the cultivars as well as to T-167 and AET-5 for most characters.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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