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Registration of Three Root‐Knot Resistant Cotton Germplasm Lines
Author(s) -
Shepherd Raymond L.
Publication year - 1987
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1987.0011183x002700010044x
Subject(s) - germplasm , crop , citation , biology , library science , knot (papermaking) , horticulture , computer science , agronomy , engineering , chemical engineering
THREE cotton (Gossypium hirsutum L.) germplasm lines with resistance to root-knot nematodes were released by the USDA-ARS and the Alabama Agricultural Experiment Station in 1986. Aub. 82 RNR Ne (Reg. no. GP-300) was derived from crossing root-knot resistant Aub 634 RNR (3) with Aub Ne 213, a nectariless release (4), and selecting for root-knot resistance and nectariless. Aub 244 RNR (Reg. no. GP-301) and Aub 299 RNR (Reg. no. GP-302) were developed by crossing Aub 634 RNR with 'Stoneville 213', and selecting for root-knot resistance. To develop the three germplasm lines, individual F2 plants were selected for root-knot nematode resistance in greenhouse tests. Since none of the selected F2 were homozygous for resistance in the F3 generation, individual plant selection for resistance was repeated within F3 progenies. Selected F3 plants were extensively progeny tested in F4 for root-knot resistance and selected in the field for desirable agronomic traits (and for nectariless in the case of Aub 82 RNR Ne). Resistance to root-knot nematodes results in reduced galling and giant cell production [caused by Meloidogyne incognita (Kofoid & White) Chitwood] in cotton roots. Rootknot nematode damage reduces nutrient and water uptake efficiency of roots, causes general plant debilitation and greatly increases susceptibility to seeding diseases (1) and fusarium wilt [caused by Fusarium oxysporum Schlect. f. vasinfectum (Atk.) Snyd. & Hans.] (5). These three germplasm lines had 45 to 50 times less root-knot nematode egg production and root galling than on Auburn 56, which has one of the highest levels of root-knot resistance available in a commercial cultivar, and 80 to 85 times less than on Stoneville 213. These germplasm lines are the first to be released that carry a high level of root-knot resistance in Stoneville 213 background. Also, Aub 82 RNR Ne is the first germplasm line to be released that combines root-knot nematode resistance with the nectariless trait. Nectariless reduces populations of several economically important insects (2). These germplasm lines should be useful in cotton improvement programs to develop cotton cultivars with resistance to root-knot nematodes, fusarium wilt, and several insects. These germplasm lines, along with the Stoneville 213 check cultivar, were tested in 1984 in a field relatively free of rootknot nematodes. Lint yield, lint percentage [(lint/seed cotton) X 100], boll weight, fiber length, strength, and micronaire in the three germplasm lines were generally comparable with that of the check. These results indicate that resistant cultivars developed by using these germplasm lines as the source of resistance should not only outperform susceptible cultivars on root-knot infested soils, but they also should compete successfully with them on noninfested soils. Small amounts of seeds of these three lines are available for distribution to cotton breeders, geneticists, and other research workers. Written requests should be addressed to R.L. Shepherd, USDA-ARS, Crop Science Research Laboratory, P.O. Box 5367, Mississippi State, MS 39762-5367.