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 × location interaction for tipburn resistance. Tipburn incidence was recorded on 10 plants in each of three repetitions in Salinas, Calif., and Yuma, Ariz., trials with 20 iceberg, 21 romaine, 11 green leaf, and six 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 percentage of 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, Ariz., trial was more conducive for TB, and had less variation (range of percentage of TB = 33% to 100% Yuma, 0% to 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 × 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 exists 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 genotype × location indicates that genetic improvement should be possible using within type crosses followed by selection in the Yuma or Salinas target environment.
USDA research farm in Salinas, CA (Trials 5 and 6 on Table 2 ) were conducted to assess yield, horticultural characteristics, and tipburn resistance using the method and variables previously discussed. In addition, post-harvest quality of whole heads
‘Anza’ differed significantly from ‘Vanguard 75’, which exhibited 8.6 leaves with tipburn per plant. The addition of ‘Tiber’ to the breeding pool is recommended, as it was selected for tipburn resistance ( Ryder and Waycott, 1998 ). As expected, the heat
, M. Itoh, H. Kanechi, M. Inagaki, N. Uno, Y. 2012 In vitro evaluation of tipburn resistance in lettuce ( Lactuca sativa L) Plant Cell Tissue Organ Cult. 108 221 227 Kozai, T. 2013 Resource use efficiency of closed plant production system with
heritability for plant breeding: An update Plant Breed. Rev. 22 9 112 Jenni, S. Hayes, R.J. 2010 Genetic variation, genotype × environment interaction, and selection for tipburn resistance in lettuce in multi-environments Euphytica 171 427 439 10.1007/s10681
19102967 Jenni, S. Hayes, R.J. 2010 Genetic variation, genotype × environment interaction, and selection for tipburn resistance in lettuce in multi-environments Euphytica 171 3 59 70 doi: 10.1007/s10681-009-0075-5 10.1016/j.geoderma.2008.03.006 Jenni, S