Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: February 15, 2005
Publication Date: June 20, 2005
Citation: Hayes, R.J. 2006. Variation for tipburn resistance in lettuce. HortScience 40:990-991. Technical Abstract: Tipburn (TB) is a physiological disorder that results in necrosis along the margins of lettuce leaves. The disorder is objectionable to consumers and reduces the shelf life of whole and minimally processed lettuce. The objectives were to 1) determine the variation for tipburn resistance in iceberg, romaine, green leaf, and red leaf cultivars and 2) determine the genotype x location interaction for tipburn resistance. Tipburn incidence was recorded on 10 plants in each of 3 reps in Salinas, CA and Yuma, AZ trials with 20 iceberg, 21 romaine, 11 green leaf, and 6 red leaf cultivars. Data were analyzed using analysis of variance type statistics of ranked data. Variation for TB resistance was found in all lettuce types at both locations, although iceberg cultivars (Average % TB: 31% Salinas; 77% Yuma) had significantly (p<0.01) higher levels of resistance at both location than romaine (58% Salinas, 81% Yuma), green leaf (52% Salinas; 88% Yuma), and red leaf (43% Salinas, 89% Yuma). The Yuma, AZ trial was more conducive for TB, and had less variation (Range of %TB: 33-100% Yuma, 0-100% Salinas). Four iceberg, one green leaf, and one red leaf genotype with industry acceptable levels of TB (<5%) were identified in the Salinas environment. Genotype x location interaction was present (p<0.01), and included rank order changes within all lettuce types. The correlation between the locations was low, 0.26, but significant (p=0.045). A need exist for romaine, green leaf, and red leaf germplasm with improved TB resistance, particularly in the Yuma environment. The presence of variation within each lettuce type and G x L indicates that genetic improvement should be possible using within type crosses followed by selection in the Yuma or Salinas target environment.