Leaf physiology and plant growth of Photinia x fraseri Dress were assessed when grown under full sunlight or (100% sun) or polypropylene shadecloth with a light transmittance of 69%, 47%, or 29% sun. Plants in 69% or 47% sun usually had the highest midday net CO2 assimilation rates (A). Net CO, assimilation rate was most dependent on photosynthetic photon flex (PPF R2 = 0.60), whereas stomata] conductance to water vapor was primarily influenced by vapor pressure deficit (R2 = 0.69). Stomatal conductance was often inversely related to sun level, and intercellular CO2 concentration was often elevated under 29% sun. Midday relative leaf water content and leaf water potential were unaffected by light regime. Light-saturated A was achieved at ≈ 1550 and 1150 μmol·m-2·s-1 for 100% and 29% sun-grown plants, respectively. Under 29% sun, plants had a lower light compensation point and a higher A at PPF < 1100 μmol·m-2·s-1. Total growth was best under 100% sun in terms of growth index (GI) increase, total leaf area, number of leaves, and dry weight (total, stem, leaf, and root), although plants from all treatments had the same GI increase by the end of the experiment. Plants in all treatments had acceptable growth habit (upright and well branched); however, plants grown in 29% sun were too sparsley foliated to be considered marketable. There were no differences in growth among the four treatments 7 months after the Photinia were transplanted to the field.
J.G. Norcini, P.C. Andersen, and G.W. Knox
Harry G. Ponder, Charles H. Gilliam, and Heather J. Dawes
Photinia Χ fraseri Dress (Fraser Photinia) plants were dug and burlapped in the morning and afternoon during midsummer with or without previous irrigation or antitranspirant treatment (di-1-p methene = Vapor Gard). Plants were shipped for one day, held for 2 weeks under lath, and then planted. Moisture stress, indicated by shoot water potential, was monitored throughout the study and survival was rated in September. Use of the antitranspirant and morning digging reduced moisture stress of plants. Morning-dug plants had 80% or greater survival even without irrigation. Afternoon digging gave low survival with or without irrigation but afternoon digging plus Vapor Gard gave 100% survival.
Robert R. Tripepi and Mary W. George
De-inked paper sludge from a newsprint mill was evaluated as a substitute for sofwood bark in container media. Rooted cuttings of `Youngstown' juniper (Juniperus horizonatlis), Fraser photinia (Photinia × fraseri), and `PJM' rhododendron (Rhododendron) were planted in 3-L plastic pots that contained potting media amended with 0%, 20%, 40%, 60%, 80%, or 90% paper sludge and 80%, 60%, 40%, 20%, or 0%, respectively, bark (by volume). All mixes contained 10% sand and 10% peatmoss except for the 90% mix, which lacked peatmoss. After 19 weeks, plant heights were measured for photinia and rhododendron, but average plant width was measured for juniper. Shoot dry weights were also determined for all species. Juniper and photinia seemed to be the most tolerant of media amended with up to 40% paper sludge, whereas rhododendron was the most intolerant species. Shoot dry weights of juniper or photinia were similar for plants grown in media containing 40% or less paper sludge. Shoot dry weights of rhododendron plants grown in 40% sludge were 23% lower than those grown in 0% or 20% paper sludge, which were similar to each other. Plant heights followed similar trends to those of the shoot dry weights. With the exception of juniper, shoot dry weights and heights were drastically reduced if the potting mixes contained more than 40% paper sludge. These results demonstrated that de-inked paper sludge could be substituted for up to 40% of the bark in a container medium for two of the three species tested.
Eucario Mancilla-Álvarez, Marco A. Ramírez-Mosqueda, Samantha Arano-Avalos, Rosalía Núñez-Pastrana, and Jericó J. Bello-Bello
genetic resource. Literature Cited Akdemir, H. Kaya, E. Ozden, Y. 2010 In vitro proliferation and minimum growth storage of fraser photinia: Influences of different medium, sugar combinations and culture vessels Scientia Hort. 126 268 275 Ali, H. Khan, M