EVALUATION OF FUSARIUM WILT-RESISTANCE IN PRIMITIVE RACES OF GOSSYPIUM-HIRSUTUM L

Seven primitive races of Gossypium hirsutum L. punctatum, marie-galant e, richmondi, latifolium, morrilli, palmeri, mexicanum and five Fl cro sses were inoculated with Fusarium f. sp. vasinfectum physiological st rain I. in the wilt held of Cixi Cotton Institute in 1987. There were highly significant differences among these primitive races. Punctatum and palmeri were highly resistant. The resistances of marie-galante an d mexicanum was similar with that of cultivar 'Simian2'; richmondi, la tifolium and morrilli were susceptible. The disease incidence of Fl in five primitive races hybridized with cultivar 'Simian2' was generally higher than that of mid-parent value. Inheritance of wilt resistance was partially dominant. In addition, 178 accessions of eight primitive races were evaluated for their resistance as before in 1989. There we re significant differences in resistance among races and intra-race ac cessions. There were wilt resistance accessions among primitive races in which disease incidence was below 10%-25%. In palmeri, marie-galant e, richmondi and punctatum, one accession was immune with 0% disease i ncidence, respectively; 22.7-77.4% accessions were susceptible with 50 % disease incidence. It showed that primitive races were mixed populat ions. They should be evaluated and screened for their utilization in c otton breeding program. Some best plants were selected from F-2 of two crosses,'Simian2' x palmeri and 'Simian2' x mexicanum, based on the r esistance to Fusarium wilt and the response to photoperiod. 11 lines h ad been obtained with good fiber quality and relatively high potential production by backcrossing improvement. These lines are now being tes ted.