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  • Author or Editor: T. Holms x
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Mature Florida ‘Valencia’ oranges [Citrus sinensis (L.) Osbeck] go through a period of reduced response to abscission chemicals. This nonresponsive period is characterized by both a reduction in the amount of ethylene induced by abscission chemicals and by decreased sensitivity of the abscission process to exogenous ethylene. During the nonresponsive period, application of the abscission chemical 5-chloro-3-methyl-4-nitro-1H-pyrazole (Release) induced less ethylene formation and less reduction in fruit removal force than at times either prior to, or following, the nonresponsive period. Experiments with radioactive Release showed that uptake was not a factor in the reduced effectiveness of this material during the nonresponsive period. Abscission of explants induced by exogenous ethylene was slower during the nonresponsive period. Mature ‘Valencias’ also go through a period of regreening. Regreening and the nonresponsive period may begin at about the same time, but regreening continues after the nonresponsive period is over. In addition, color changes induced by exogenous ethylene remain similar throughout the regreening and nonresponsive periods, but abscission of explants induced by exogenous ethylene is reduced only during the nonresponsive period. These differences in time-course and ethylene sensitivity between regreening and the nonresponsive period allow differentiation of these two processes.

Open Access

Simple sequence repeats (SSRs) were isolated from a size-fractionated genomic DNA library of watermelon (Citrullus lanatus L. cv. New Hampshire Midget). Screening of the library with five oligonucleotide probes, including (GT)11, (AT)11, (CT)11, (GC)11, and (TAA)8, detected the occurrence of 96 positive colonies among ≈8000 recombinants. Automated DNA sequencing revealed the presence of SSRs. PCR primer pairs homologous to the regions flanking the SSR loci were synthesized commercially and used to screen 56 watermelon genotypes for the occurrence of SSR polymorphisms. Amplification products were separated using nondenaturing PAGE. Eighty percent of the primer pairs produced amplification products of the expected size and detected polymorphisms among the genotypes examined. The use of SSRs for watermelon germplasm characterization is discussed.

Free access

In an effort to promote commercial vegetable production in North Dakota and to determine the cabbage (Brassica oleracea L. Capitata Group) hybrids best adapted to this area, we conducted cabbage variety trials from 1993 to 1997 at the Oakes Irrigation Research Site in North Dakota. We evaluated cabbage yield and quality characteristics, and also demonstrated cabbage production to farmers in this area. Cabbage grows very well in North Dakota. Highest yields were in 1996 when temperatures in May were coolest. Lowest yields were in 1994 when May temperatures were the hottest. Hybrids with the highest yields and best appearance included `Gideon', `Bronco', and `Royal Vantage' for the fresh market, and `Fresco', `Cheers', `Bravo', and `Bronco' for the processing market. Despite differences in weather over the 5 years of the study, cabbage hybrids were fairly consistent as to yield and quality characteristics. Suitability of cabbage hybrids for coleslaw and shredded cabbage was tested through sensory evaluations in 1993. `SCB8101', `Stonehead', `Hinova', `Green Boy', and `Charmant' scored highest on these sensory evaluations in this single-year test.

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