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

The genus Rosa comprises ≈150 species that are widely distributed in diverse climates and habitats throughout the Northern Hemisphere ( Quest-Ritson and Quest-Ritson, 2003 ; Rehder, 1940 ) from subtropical to cold-temperate regions. China’s 95

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Le Luo, Chao Yu, Xuelian Guo, Huitang Pan, and Qixiang Zhang

As one of the biodiversity centers of wild Rosa , China is home to 95 species (65 endemic) of Rosa , accounting for nearly half of the world total ( Ku and Kenneth, 2003 ). The Xinjiang Uygur Autonomous Region is a large and sparsely populated

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Agnieszka Masny and Edward Żurawicz

‘Pink Rosa’ is a new late strawberry cultivar from the Research Institute of Horticulture in Skierniewice, Poland broadening the assortment of strawberry cultivars for fresh market. The fruit of ‘Pink Rosa’ are large, regular in shape (wide conical

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Jeffrey H. Gillman, David C. Zlesak, and Jason A. Smith

Roses in nursery and landscape settings are frequently damaged by black spot, whose causal agent is the fungus Diplocarpon rosae F.A. Wolf. Potassium silicate was assessed as a media-applied treatment for decreasing the severity and incidence of black spot infection. Roses were treated with 0, 50, 100, or 150 mg·L-1 silicon as potassium silicate incorporated into irrigation water on either a weekly or daily schedule. Five weeks after treatments were initiated, plants were inoculated with D. rosae. Roses began to show visual symptoms of infection §4 days later. Roses that had 150 mg·L-1 silicon applied on a daily schedule had significantly more silicon present in their leaves than other treatments as measured by scanning electron microscopy and energy-dispersive x-ray analysis. In addition, roses that had 100 and 150 mg·L-1 silicon applied on a daily schedule had fewer black spot lesions per leaf and fewer infected leaves than any of the other treatments by the end of the experiment 7 weeks later. Although roses treated with higher levels of silicon on a daily basis fared better than roses in the other treatments, all of the roses were heavily infected with D. rosae by the end of the study. The results reported here indicate that using potassium silicate in irrigation water may be a useful component of a disease management system.

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Yan Ma and Junyu Chen

From 1986 through 1993 wild rose species were investigated throughout China to catalog and to characterize the rose germplasm resources in mainland China. Many of the 94 rose species and 144 rose varieties in China have not been extensively utilized. The basic features of Chinese rose species are as follows. (1) There are many valuable and rare Rosa species in China. These species are sources of many unique and outstanding characters such as intense fragrance, white and yellow flower color, recurrent flowering and resistance to stress. More than 80% of the rose species in China are native to only China. (2) Although most Rosa species are still in the wild state, a few species cultivated from very early time have many forms available. (3) The number of rose species gradually increases from Northeast to Southwest China. The distribution centers of Rosa species in China are Sichuan and Yunnan Provinces. Chinese rose species can be introduced and used directly in gardens, or in breeding programs to develop new roses.

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Natalie Anderson* and David Byrne

Poor germination in Rosa has been an obstacle to breeding programs for years. Rose breeders generally stratify rose seed under cool, moist conditions for 4-10 weeks by planting directly into the seedling flat/bed or in a small container followed by planting the germinating seed into the seedling flat/bed. This experiment used 9 genotypes and compared these two approaches combined with variations in the stratification media (sand, perlite, sphagnum moss and Sunshine Mix #4). Over all stratification media and genotypes, germination was not influenced by whether the seed was stratified directly in the seedling flat/bed or in a small container. However, the process of transplantation of the delicate germinating seed from the small container to the flat/bed resulted in greater mortality of the germinating seedlings. he stratification media affected the germination of the rose seed. Sunshine Mix #4 gave the best germination as compared to all other media types tested. As expected the germination of the genotypes varied greatly, ranging from 0.7% to 37.1%.

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Yan Ma, David H. Byrne, and David M. Stelly

Mitotic chromosome numbers and measurements were determined from enzymatically digested shoot tips for 14 species of Rosa, subgenus Hulthemia, Platyrhodon, and Rosa (the latter represented by sections Pimpinellifoliae, Cinnamoneae, Synstylae, Banksianae, Laevigatae, and Bracteatae). All were 2n = 14 or 2n = 28, as expected from previously published chromosome counts in Rosa. Arm lengths of chromosome pairs measured from digitized images were analyzed for similarity using a least-squares algorithm. On this basis, tetraploid species were compared to their diploid relatives. This study demonstrates the value of karyotypic data in combination with morphological and ecological information for examining the evolution of Rosa.

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Chengyuan Liu, Guoliang Wang, Hui Wang, Tao Xia, Shouzhou Zhang, Qigang Wang, and Yanming Fang

The genus Rosa L. comprises ≈200 species distributed widely throughout the temperate and subtropical regions of the northern hemisphere ( Ku and Robertson, 2003 ; Rehder, 1940 ; Wissemann, 2003 ). However, less than 10 species have likely

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Qianni Dong, Xinwang Wang, David H. Byrne, and Kevin Ong

disease resistance to black spot have been characterized in roses. Vertical or complete resistance, which blocks sporulation and severely restricts the mycelial growth of the pathogen, is usually controlled by major dominant genes ( Rdr or Rosa disease

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Dao-Jing Wang, Jing-Wen Zeng, Wen-Tao Ma, Min Lu, and Hua-Ming An

; Cui et al., 2016 ; Li et al., 2015 ; Liu et al., 2016a ; Pan et al., 2015 ; Wang et al., 2016 ; Zhao et al., 2015 ). Rosa roxburghii Tratt (RR) (Rosaceae) is a perennial rosebush native to China. Its cultivation area has gradually expanded