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formulation and dried in a laminar flow hood for 4 h. The photocatalytic activity was tested on Xanthomonas sp. strain Xr-1 isolated from Rosa ‘Noare’ in Quincy, FL. The bacterial strain stored in 30% glycerol at –80 °C was plated on Yeast Nutrient Agar (YNA

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Roses are adapted for growth and production on acid to slightly acid soil. When grown on alkaline soil sites, without extensive soil modification and acid forming and/or iron chelate fertilization, growth is reduced and severe iron chlorosis is prevalent. This study screened 24 Rosa rootstock species and selections on one acid and two alkaline soil sites for 2 consecutive years. Plants were observed for chlorosis, chlorophyll content, fresh and dry weight production and overall quality. A final reciprocal grafting study using susceptible and tolerant selections was conducted to assure the scion could realize the adaptability of the rootstock. Overall, the following five selections consistently exhibited greater growth and decreased chlorosis on the alkaline sites: R. odorata, R. canina, R. manetii, R. sp. “Mexican”, R. fortuniana, and R. multiflora selection K-l. All other R. multiflora selections performed poorly. On the acid soil site, all rootstocks grew well. When susceptible selections were budded onto tolerant rootstocks, the scions exhibited a higher degree of tolerance. Tolerant selections budded onto susceptible rootstocks exhibited increased chlorosis and decreased growth.

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Two-year-old Rosa hybrida L. `Royalty', `Emblem', and `Samantha' plants were pinched 20 Oct. and 28 Dec. 1992 for Christmas and Valentine's Day crops. Two greenhouses received ambient CO2 and two were enriched to 1200 ppm CO2 when vents were closed. All temperature set points were 22C/17C day/night. At 10 and 25 days after pinch, and at flowering, 5 shoots from each bench location were destructively sampled for leaf (node) number, stem diameter, stem length, and fresh weights of stem, leaves, and flower bud. Time to visible bud and to flowering from pinch also were recorded.

Analysis of variance for the 1992 Christmas crop did not find significant differences for flowering times, but trends in response were evident. The 3 cultivars had mean flowering times of: `Royalty', 51.3 days; `Emblem', 52.3 days; and `Samantha', 54.0 days. Enrichment with CO2 showed a trend for decreased average flowering times for all 3 cultivars. Results from the 1993 Valentine's Day crop will also be presented.

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, generating sales of $203.5 million ( U.S. Department of Agriculture, National Agricultural Statistics Service, 2015 ) There are four subgenera under the genus Rosa , which has more than 100 species, ranging from diploid to decaploid. There are more than 30

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Abstract

The breeding of hybrid rose cultivars is part of the ornamental rose industry, but there have been few studies concerned with the factors limiting reproduction in the genus Rosa L. In this study, 28 species of Rosa were examined under field conditions for self- and cross-compatibility relationships. Twenty-five specimens of 25 species were tested for self-compatibility. All of the 23 diploid plants tested exhibited more than 96%. Twelve of the 16 polyploid plants preserved the 96% self-incompatibility reaction. A distinct separation existed between self-compatible and self-incompatible polyploid plants. Four of the 5 diploid cross-fertilizations produced unexpected reciprocal differences. Significant reciprocal differences were not obtained from the polyploid level cross-fertilizations. Some parthenocarpy occurred in the R. stellata species. Pollen viability and abundance, daily maximum and minimum temperature, and maximum and minimum relative humidity were not correlated with the compatibility reactions.

Open Access

vegetative nodes and time to flowering are affected by high-temperature stress on two garden rose cultivars. Materials and Methods Plant material. Liners of Rosa L. cultivars BD and KO were planted in 0.72-L pots in LC-1 soilless medium (SunGro Horticulture

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Abstract

Abscisic acid 4 (ABA), when applied as an immersion application at 200 and 400 ppm during cold storage or as a spray application at 100 and 200 ppm at 2 stages of growth, was evaluated as an inhibitor of bud break and shoot elongation in dormant plants of Rosa cv. Helen Traubel and Syringa cv. Monge. ABA applied on 2 consecutive days at 100 and 200 ppm inhibited bud break in Rosa, but did not inhibit shoot elongation. ABA did not inhibit terminal and lateral bud break or shoot elongation in Syringa. Immersion applications at several dates during cold storage inhibited bud break and shoot elongation in Rosa and inhibited terminal and lateral bud break in Syringa. The most effective concentration in inhibiting bud break was 400 ppm. Time of application significantly affected bud break in Rosa and lateral bud break in Syringa, but did not alter shoot elongation in either plant.

Open Access

One hundred sixteen rose (Rosa spp.) cultivars were evaluated under minimal input conditions in north-central Texas for 3 years. Plant quality data included overall plant performance, number of flowers, percentage of bloom coverage, final vigor, and survival. Disease ratings for black spot (Diplocarpon rosae), petal blight (Alternaria alternata), powdery mildew (Sphaerotheca pannosa), and aphid (Myzus spp.) infestations were previously reported. Of the original 116 cultivars, 25 had 50% or higher mortality during the trial. Own-root cultivars performed significantly better than the grafted cultivars and had significantly better survival (P = 0.001). As a class, the Polyantha cultivars exhibited the best overall performance, mean bloom percentage, final vigor and survival, while cultivars in the Hybrid Tea class had the worst performance in all measures. Foliar nutrient content, bloom number, and mean percentage of bloom were not good predictors of overall performance. Of the diseases monitored, black spot was the most severe and was closely correlated to overall performance and final vigor, but was not the only factor determining overall performance. The top five cultivars in mean overall performance were RADrazz (Knock Out™), Caldwell Pink, Sea Foam, Perle d'Or, and The Fairy, in descending order.

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Abstract

The tragic and sudden death of J. T. Rosa, Jr. occurred at a comparatively early age in the midst of what surely was to be his most productive years. 3 He left behind him, however, a legacy of more completed, and more seminal research than most of us are likely to accomplish, should we be lucky enough to survive the hazards of modern day living to reach the biblical age of three score and ten. As I am one of the few people (living) who knew Professor Rosa from the vantage point of a student, I wish to record my recollections of this inspiring teacher and productive scientist. In completing this task, I have had the assistance of three individuals: V. R. Boswell, H. A. Jones and Gilbert W. Scott. Dr. Jones was a colleague, and Drs. Boswell and Scott were students of Dr. Rosa and worked under his supervision.

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Abstract

The responses of 13 cultivars of Hibiscus rosa-sinensis L. to Meloidogyne javanica (Treub) Chitwood and of 12 cultivars of H. rosa-sinensis to M. incognita (Kofoid & White) Chitwood were determined in 2 greenhouse inoculation experiments. ‘Pride of Hankins’ was highly susceptible to M. javanica, ‘Philipino’ was highly susceptible to M. incognita, and several other cultivars showed moderate levels of galling from the latter species. The cultivars which were least susceptible to both nematode species were ‘President’, ‘Florida Sunset’, ‘Old Gold’, ‘Go-Go Girls’, ‘Anderson Crepe’, and ‘Delight’.

Open Access