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S. Mark Goodwin, Christopher J. Edwards, Matthew A. Jenks, and Karl V. Wood

Roses are among the most important ornamental plants, used both indoors as potted and cut flowers and in the outdoor managed landscape. As is well known, roses are susceptible to many kinds of environmental stress, including those incited by

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Yan Ma, M. Nurul Islam-Faridi, Charles F. Crane, David M. Stelly, H. James Price, and David H. Byrne

To our knowledge, there has been no published technique to produce consistently high-quality slides of somatic chromosomes of roses (Rosa sp.). Therefore, various pretreatments, fixatives, digestions, stains, and maceration and squashing methods were tested to identify a procedure to produce clear, well-spread chromosomes from shoot tips. The best results were obtained after pretreatment in a mixture of 0.1% colchicine and 0.001 m 8-hydroxyquinoline for 4 h, and fixation in 2 acetone: 1 acetic acid (v/v) with 2% (w/v) polyvinylpyrrolidone. The darkest-stained chromosomes were obtained with carbol-fuchsin staining of air-dried cell suspensions that had been spread in 3 ethanol: 1 acetic acid (v/v).

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David H. Byrne, Patricia Klein, Muqing Yan, Ellen Young, Jeekin Lau, Kevin Ong, Madalyn Shires, Jennifer Olson, Mark Windham, Tom Evans, and Danielle Novick

The rose is attacked by a plethora of fungal, bacterial, and viral pathogens which cause a wide range of symptoms including leaf spotting, distortion, discoloration, and defoliation, reducing the ornamental value of these plants but usually not

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Mark A. Rose, David J. Beattie, and John W. White

Two distinct patterns of whole-plant transpiration (WPT) were observed in `Moonlight' rose (Rosa hybrida L.) using an automated system that integrated a greenhouse climate computer, a heat-balance sap-flow gauge, an electronic lysimeter, and an infrared leaf temperature sensor. One pattern consisted of a steady rate of transpiration in a stable greenhouse environment. The second pattern consisted of large oscillations in transpiration unrelated to any monitored microclimate rhythms. These oscillations had a sine-wave pattern with periods of 50 to 90 minutes and ranged from 2 to 69 g·h-1 in natural light and 3 to 40 g·h-1 under high-pressure sodium lamps at night. Leaf-air temperature difference (T1 - Ta) also oscillated and was inversely related to transpiration rate. Oscillatory transpiration has not been reported in roses. Plant scientists need to recognize the complex and dynamic nature of plant responses such as the oscillatory pattern of WPT monitored in Rosa hybrida when selecting monitoring and control strategies.

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H. Brent Pemberton, Kevin Ong, Mark Windham, Jennifer Olson, and David H. Byrne

Rose rosette disease is incited by a negative-sense RNA virus (genus Emaravirus ), which is vectored by a wind-dispersed eriophyid mite ( P. fructiphilus ) ( Di Bello et al., 2015a ; Laney et al., 2011 ). Symptoms on roses include witches broom

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Chao Yu, Le Luo, Hui-tang Pan, Yun-ji Sui, Run-hua Guo, Jin-yao Wang, and Qi-xiang Zhang

species (65 endemic) account for nearly half of the world’s Rosa species ( Ku and Robertson, 2003 ). Therefore, China is a center of distribution of Rosa as it is with numerous other cultivated plants ( Brichet, 2003 ), and China’s roses are a great

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Mark A. Rose, John W. White, and Joel L. Cuello

Recently developed stem flow gauges that allow for direct, accurate, non-invasive, and continuous measurement of plant sap flow rates have not been used to monitor transpiration of floricultural plants grown in greenhouses.

A Dynamax SGA10 heat-balance sap-flow sensor was mounted on a potted rose plant's main stem containing a total leaf area of 0.52 m in order to monitor transpiration. The sensor was connected to a CR21X Micrologger for data calculation and temporary storage. The results showed average midday sap-flow rates range from 20-30 g·hr-1 to 50-70 g·hr-1 at low and high levels of PPF, respectively. Nighttime levels of 4-7 g·hr-1 persisted throughout early winter trials. Monitoring transpiration of the same rose stem using a lysimeter revealed a significant linear correlation (r2 = 0.999) between the lysimeter and the stem flow gauge values.

In the future, research will be conducted with the gauge to investigate relationships between microclimatic variables, photosynthesis, and transpiration.

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A. Vainstein and H. Ben-Meir

This study was supported by a grant from the Robert Szold Institute for Applied Science of the P.E.F. Israel Endowment Fund, the Israeli Ministry of Agriculture, and the Rose Growers Fund (Association of Israeli Flower Growers). We thank N. Zieslin

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James E. Altland and Charles Krause

Micromax (The Scotts Co., Marysville, OH) micronutrients and 1.2 kg·m −3 gypsum. Containers (15 cm i.d.) were filled with substrate and planted with Oso Easy™ Paprika roses ( Rosa ‘ChewMayTime’) that were ≈10 cm tall and 15 cm wide at the time of planting

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Xianqin Qiu, Hao Zhang, Hongying Jian, Qigang Wang, Ningning Zhou, Huijun Yan, Ting Zhang, and Kaixue Tang

The genus Rosa comprises ≈200 species and 30,000 cultivated varieties, but only 10 to 15 species have contributed to the modern roses ( Cairns, 2007 ; Chen, 2001 ). Compared with the abundant genetic diversity of the wild species, the genetic