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George M. Greene II, Cynthia L. Barden and Laura Lehman-Salada

York Imperial is an important processing apple cultivar in the mid-Atlantic region and is often stored for up to eleven months. This experiment was designed to further examine the optimum CA storage conditions for this cultivar. Six orchards were used as statistical blocks. The factorial experiment was set up with 2 temperatures (0 and 2C), 2 oxygen (1 and 2%) and 3 carbon dioxide concentrations (2,3.5 and 5%). Sample size was 20 fruit at all analysis periods (at harvest, 4, 6, and 8 months). The apples were stored in a recirculating CA research facility and evaluated for firmness, soluble solids and weight loss. In the overall statistical analysis, orchard blocks, harvest dates and storage times significantly influenced all 3 quality parameters. Differences between blocks at harvest were substantial with firmness ranging from 9.5 to 11.3 kg and the soluble solids ranging from 12.8 to 14.8%. At the third storage removal (8 months), low oxygen increased firmness and decreased weight loss during storage while at the lower temperature, apples were firmer, had higher soluble solids and less weight loss than at the higher temperature. Although statistically significant, the differences may not be commercially important Block differences were generally maintained throughout storage.

Free access

Ying Wang, Laura L. George, Gregory L. Reighard, Ralph Scorza and Albert G. Abbott

Evergreen genotypes of peach [Prunus persica (L.) Batsch] have been identified in Mexico, where terminal growth on evergreen trees is continuous under favorable environmental conditions. This evergreen trait in peach is controlled by one single gene (evg), and this evergreen condition is homozygous recessive. Four dominant AFLP markers, EAT/MCAC, ETT/MCCA2, EAT/MCTA, and ETT/MACC, were found to be tightly linked to the evg locus at 1 cM, 4.6 cM, 5.8 cM, and 11 cM, respectively. All four markers were sequenced and identified. A peach BAC library was constructed by using the pBeloBAC11 vector for building the physical map for the evg gene. This library represents four times the coverage of the peach genome with the average insert size of 50 to 70 kb. The EAT/MCAC AFLP marker fragment was used for screening the peach BAC library. A single BAC clone, 18F12, was confirmed to contain this fragment. The final BAC contig for this evg gene region and the potential homology between peach and Arabidopsis thaliana will be presented and discussed.

Open access

Laura Jalpa, Rao S. Mylavarapu, George J. Hochmuth, Alan L. Wright and Edzard van Santen

Use efficiency of applied nitrogen (N) is estimated typically to be <50% in most crops. In sandy soils and warmer climates particularly, leaching and volatilization may be primary pathways for environmental loss of applied N. To determine the effect of N fertilization rate on the N use efficiency (NUE) and apparent recovery of N fertilizer (APR), a replicated field study with ‘BHN 602’ tomato (Solanum lycopersicum) grown in sandy soils under a fertigated plastic-mulched bed system was conducted using ammonium nitrate as the N source at four different rates (0, 150, 200, and 250 lb/acre). Spring tomato was followed by fall tomato in the same field, a typical cropping sequence in north Florida. Fertigation of N fertilizer was applied weekly in 13 equal doses for both seasons. The highest NUE was 12.05% (spring) and 32.38% (fall), and the highest APR was 6.11% (spring) for the lowest rate of N applied (150 lb/acre). In the fall, APR was unaffected by fertilizer N rates and ranged from 12.88% to 19.39%. Nitrogen accumulation in tomato plants were similar among the three N fertilizer rates applied (150, 200, and 250 lb/acre), though compared with no N fertilizer application, significant increases occurred. Whole plant N accumulation, NUE, and APR declined or remained similar when N rates increased above 150 lb/acre. Additionally, a regression analysis and derivative of the quadratic fresh yield data showed that yields were maximized at 162 and 233 lb/acre N in the spring and fall seasons, respectively.