Transgressive Segregation for Root-Knot Nematode Resistance in Cotton1
- R. L. Shepherd2
F6 families of Gossypium hirsutum L. ✕ ‘Mexico Wild’ (a root-knot tolerant primitive G. hirsutum from Mexico) were advanced through F10, with selection in greenhouse tests for resistance to root-knot nematodes [Meloidogyne incognita acrita (Kofoid & White, 1919) Chitwood, 19491. A disinfected larval screening technique effectively classified 85% of the F6 families as intermediate to highly susceptible, even though they had been selected in F2 through F4 in the field for root-knot resistance in highly infested soil.
Two F10 lines, designated A623 and A61, having the highest resistance known to root-knot in G. hirsutum, were developed. These lines were transgrassive segregates for resistance. Root-knot resistance in the F1 generation from resistant A623 ✕ susceptible ‘Stoneville 213,’ ‘Coker 201,’ and ‘Dixie King II’ was incompletely dominant.
Fusarium wilt [Fusarium oxysporum Schlecht. f. vasinfectum (Atk.) Snyd. ✕ Hans.] resistance in the above material was highly associated with root-knot resistance. Therefore, it may be possible to breed for fusarium wilt resistance by breeding solely for high root-knot resistance.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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