James L. Brewbaker and Brian T. Scully
Sandra B. Wilson, Keona L. Muller, Judith A. Gersony and Brian T. Scully
Carlos A. Parera, Daniel J. Cantliffe, Peter J. Stoffella and Brian T. Scully
Poor emergence and seedling vigor are common characteristics of many sweet corn (Zea mays L.) cultivars with the shrunken-2 (sh2) mutant endosperm. A rapid and reliable predictor of sweet corn seed field emergence would improve the potential for high quality crops. Field emergence of seven sh2 sweet corn cultivars grown at seven environments in Florida were correlated with laboratory vigor tests. Factor analysis was used to separate noncollinear vigor tests for subsequent multiple regression models. The best single predictor test (R 2 = 0.93***) was an index based on leachate conductivity and germination percentage after a complex stress vigor test involving incubation at 15C. Leachate conductivity after 3 h soaking at 25 or 30C (R 2 = 0.9W***), soil cold test (R 2 = 0.9***), alternate temperature stress conductivity test (R 2 = 0.88***), standard germination test at 30C (R 2 = 0.88***), and an index involving incubation at 25C (R 2 = 0.88***) were also good predictors of field emergence. Noncollinear tests including the towel germination test at 25 C and an alternate temperature stress conductivity test resulted in the best two factor predictor (r 2 = 0.89***), and with glutamic acid decarboxylase activity (GADA) was the best three factor predictor (r 2 = 0.93***). The index of conductivity and complex vigor test (ICS) evaluated seed membrane integrity and potential for pathogen infection, respectively, and can be considered as major factors affecting emergence in sh2 sweet corn.
James J. Salvatore, Mark A. Ritenour, Brian T. Scully and L. Gene Albrigo
Up to three hurricanes (Charley, Frances, and Jeanne) passed over the same citrus-producing areas of Florida in August and September 2004. In October 2005, hurricane Wilma also passed over South Florida. We began evaluating citrus tree recovery in four commercial groves (red and white grapefruit, and `Murcott' tangerine) following the 2004 hurricanes to determine how quickly commercial groves recover following such catastrophic events. We previously reported that, among other things, even branches formed after the last 2004 hurricane matured sufficiently to flower the following spring, but to a lesser extent than older shoots. Here, we report hurricane effects on tree yield, fruit quality, and shelf life. Fruit loss was dramatic following the 2004 hurricanes (>90%). Fruit loss was also substantial following hurricane Wilma, with `Murcott' yields reduced 18% and grapefruit yields reduced 58%-65%. However, in comparison to 2003 pre-hurricane yields, yields following hurricane Wilma declined only 9% for `Murcott,' and 26%-40% for grapefruit. These yield reductions are less than the fruit lost due to the present year's hurricane. Therefore, the citrus trees studied demonstrated tremendous resilience and, if not for another hurricane the following year, would have likely exceeded pre-hurricane yields only 1 year after the devastating 2004 hurricanes. Effects of the hurricanes on harvested fruit quality and shelf life will also be discussed.