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K.C. Pee and C.E. Johnson

Trunk diameter, yield, root sprout production, and tree mortality of `Redglobe' peach were evaluated over a 14 year period on 5 rootstocks; `Lovell', `Halford', `Nemaguard', `Bailey', and `Siberian C'. Trunk diameter in year 14 was not different for trees on `Lovell' and `Halford', with diameters on 23.7 and 23.5 cm respectively, as compared to 93 and 45 kg on `Halford'. These were not significantly different from each other. Both `Lovell' and `Halford' produced 1.8 root sprouts per tree or less both years. Trunk diameter on `Nemaguard', `Bailey', and `Siberian C' was different from `Lovell' and `Halford'. Yields on `Nemaguard', `Bailey', and `Siberian C' were 92, 88, and 41 kg respectively, in year 12, with trees on `Siberian C' being different from the other 4 rootstocks. Yields in year 14 were 60 kg on `Nemaguard', 50 kg on `Bailey', and 28 kg on `Siberian C'. Root sprout averages per tree on `Nemaguard' were 1.6 and 6.7 in years 8 and 14 while `Bailey' averaged 1.1 and 7.7. Root sprouts on `Siberian C' were low in year 8, but increased in year 14 to 15.1 per tree. Tree mortality on `Siberian C' was 44% by year 14.

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J.T. Payne and C.E. Johnson

Twenty-six muscadine cultigens were evaluated for fruit size, color, soluble solids, and other horticultural characteristics pertaining to fresh market use. Seventeen cultigens were evaluated for 7 years and 9 were evaluated for 2 years. Entries with the largest fruit size were `Granny Vale', `GA 33-1-4', `Sweet Jenny', and `Black Fry' with fruit weights averaging over 10.5 grams each. `Summit', `GA 33-1-4' `Sweet Jenny', `Fry', `Dixieland', and `GA 9-4-1' were consistently over 17% soluble solids during the years of this study. The yield per vine was highest on `Watergate', `Carlos', `Summit', `Higgins', and `Redgate'. The highest average yield was 30.0 kg per vine on `Watergate'. Recently released cultivars `Black Fry', `Black Beauty', and `Granny Vale' exhibited extremely good characteristics for the fresh market industry.

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G.A. Picchioni and C.E. Johnson

Ground water salinity is a major concern for crop diversification in Louisiana where mayhaw (Crataegus opaca) is being considered as a new fruit crop. Its saline resistance is unknown; thus, we evaluated it in greenhouse conditions. One-year-old seedlings were irrigated with tap water, 10 mm NaCl (+ 2 mm CaC12), and 25 mm NaCl (+ 5 mm CaC12) for 9 weeks. Leaf and stem dry matter accumulation were reduced by an average of 80% and 60% below controls, respectively, in seedlings irrigated with 25 mm NaCl. The fresh weight: dry weight ratios of stems and roots also were reduced by 25 mm NaCl (15% and 28% below controls, respectively). Notably smaller leaf growth suppression occurred when 25 mm NaCl was supplemented with 5 mm CaC12 compared to 25 mm NaCl in the absence of CaC12. The fact that CaC12 partially reversed the leaf growth inhibition may indicate that Ca fertilization could be of benefit for mayhaw orchards relying on saline ground water.

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C.E. Johnson, J.T. Payne, and K.C. Pee

Controlled crosses of a Vermillion red flesh color cultivar with 4 normal red flesh color cultivars were made. F1, F2, and backcross generations were grown in the field and the fruits evaluated for flesh color. All fruits of the F1 generation were Vermillion. The F2 generation segregated to a 9:7 ratio of vermillion to normal in all crosses. The probabilities of fit ranged from 0.10 to 0.95. This ratio is indicative of two dominant genes with complementary effects or double recessive epistasis, Backcrosses to the dominant parent produced almost all vermillion flesh fruit. Backcrosses to the recessive parents did not fit any documented ratios. Further analysis of the BC generations seems to suggest that flesh color is controlled by two dominant genes.

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C.E. Johnson, J.T. Payne, and K.C. Pee

Controlled crosses of a Vermillion red flesh color cultivar with 4 normal red flesh color cultivars were made. F1, F2, and backcross generations were grown in the field and the fruits evaluated for flesh color. All fruits of the F1 generation were Vermillion. The F2 generation segregated to a 9:7 ratio of vermillion to normal in all crosses. The probabilities of fit ranged from 0.10 to 0.95. This ratio is indicative of two dominant genes with complementary effects or double recessive epistasis, Backcrosses to the dominant parent produced almost all vermillion flesh fruit. Backcrosses to the recessive parents did not fit any documented ratios. Further analysis of the BC generations seems to suggest that flesh color is controlled by two dominant genes.

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K.C. Pee, C.E. Johnson, E.W. Bush, and E.A. Drummond

Seed of 15 watermelon cultivars were evaluated for germinating ability at sub-optimum temperatures. Seeds of each cultivar were exposed to 12.8, 15.6, 18.3, 21.1, and 30.0°C for 8 days in a germinator in accordance to standard seed testing rules. Radical emergence was evaluated on day 5 and day 8. None of the cultivars germinated at 12.8C after 8 days exposure. At 15.6°C, 'Red-N-Sweet' and `Blackstone' had germinations of 54 and 40 percent respectively on day 5, and both increased to over 80 percent on day 8. At 18.3°C `Red-N-Sweet' and `Blackstone' exhibited at least 90 percent germination after 5 days while the other 14 cultivars ranged from 2.5 to 86 percent. At 21.1°C all cultivars except `Black Diamond' and `Allsweet' had germinations of 80 percent or higher on day 5. Germination increased to 90 percent or above by day 8 except for `Black Diamond' at 83 percent. There were no significant differences among cultivars at the 30°C optimum germinating temperature with cultivars having 89.5 percent or higher germination.

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Damon C. Johnson, Murray E Duysen, and Chiwon W. Lee

The influences of elevated iron concentrations in the nutrient solution and light intensity on growth and the chlorophyll and chloroplast development in Kentucky bluegrass (Poa pratensis) `Touchdown' (C3), creeping bentgrass (Agrostis palustris) `Penncross' (C3), and buffalograss (Buchloe dactyloides) (C4) were investigated. Plants established in peatlite medium in 11-cm pots were fertilized with a Hoagland solution containing various iron concentrations (0, 0.01, 0.1, 1, 2, 4, 6, 8, 10 mM Fe+2) under two different light regimes. Preliminary results indicated that no biomass reduction or toxic symptoms developed in buffalograss when grown with iron levels up to 8 mM under high light conditions. As Fe+' levels were raised, plants became progressively greener with both the chlorophyll-a and chlorophyll-b contents increased. In Kentucky bluegrass, the sizes of chloroplasts and grana stacks in the cell were larger when grown with 2 mM than 0.05 mM Fe+2 in the fertilizer solution. The interactions of iron concentration and light intensity on pigmentation and photosynthesis of the three species are currently being determined.

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Y.H. Huang, C.E. Johnson, and M.D. Sundberg

Floral morphology and differentiation of `Sharpblue' southern highbush blueberry (Vaccinium corymbosum L.) were studied under natural growing conditions. There was no rest period during floral development of `Sharpblue' blueberry in Louisiana. Basal florets were already present within a racemic inflorescence in early September. All floral and reproductive organs were clearly visible in early December. Microspores and pollen grains were observed in mid- and late-January, respectively. Megasporocytes, two-cell, four-cell, and seven-cell embryo sacs were found to be simultaneously present in developing ovules in late January, suggesting that megasporogenesis and megagametogenesis in `Sharpblue' blueberry are asynchronous.

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C.E. Johnson, J.T. Payne, W.A. Young, and E.W. Bush

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C.E. Johnson, W.J. Bourgeois, P.W. Wilson, J.E. Boudreaux, and F.J. Peterson