HORTSCIENCE 48(12):1452–1456. 2013. ephemeraeformis Haworth) (Lemke et al., 2005), fungal cankers caused by Seiridium Nees ex Link spp. and Botryosphaeria dothi- Chlorophyll, Carotenoid, and Visual dea (Moug.) Ces. et De Not., and cercospora needle blight (Cercosporidium sequoiae Ellis Color Rating of Japanese-cedar Grown and Everh.) (Martinez et al., 2009). Japanese- cedars exhibit less susceptibility to bagworm in the Southeastern United States infestations, and cultivars are available that have reduced interior branch death (Tripp Ryan N. Contreras1,4 and Raulston, 1992); however, the species is Department of Horticulture, Oregon State University, 4017 Agricultural and not problem-free. Redfire (Phyllosticta aurea Life Sciences Building, Corvallis, OR 97331 C.Z. Wang) is a fungal pathogen that can attack stressed japanese-cedars and cause John M. Ruter2 stem death, particularly on older foliage (Cox Allan Armitage Professor of Horticulture, Department of Horticulture, and Ruter, 2013; Tripp, 2005). Also, as Dirr (2009) notes, there is not a fast-growing, tree- University of Georgia, 221 Hoke Smith, Athens, GA 30602 like cultivar that remains green during winter. James S. Owen, Jr.1 Winter browning in japanese-cedar is often unsightly and undesirable to consumers, which Department of Horticulture, Virginia Polytechnic Institute and State may have contributed to why it has remained University, Hampton Roads Agricultural Research and Extension Center, underused in landscapes. 1444 Diamond Springs Road, Virginia Beach, VA 23455 Winter browning in japanese-cedar oc- 3 curs through the conversion of chloroplasts to Andy Hoegh chromoplasts during winter (Ida, 1981). This Laboratory for Interdisciplinary Statistical Analysis, Department of Statistics, transition takes place only in sun-exposed Virginia Polytechnic Institute and State University, 406-A Hutcheson Hall, leaves during periods of low temperature, Blacksburg, VA 24061 indicating that photoinhibition likely plays a role (Han and Mukai, 1999; Ida, 1981). Plants Additional index words. Cryptomeria japonica, photoinhibition, pigments, winter-browning have several mechanisms to cope with excess light during periods of low temperature when Abstract. Japanese-cedar has been underused in landscapes of the United States until Calvin cycle activity is limiting, including recent years. There are now over 100 cultivars, many of which are grown in the southeast reduction of chlorophyll, pH-dependent xan- of the United States. Performance of cultivars has been described from U.S. Department thophyll cycle, increased levels of carotenoids, of Agriculture (USDA) Zone 6b to USDA Zone 7b; however, there are no reports on how and production of antioxidants or reactive cultivars perform in USDA Zone 8. The current study was conducted to measure oxygen species (ROS) scavenging enzymes. chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid content and assign visual During winter, japanese-cedar has been shown color ratings to determine if there was a relationship between pigment values and to demonstrate two principle mechanisms to perceived greenness, which generally is regarded as a desirable and potentially heritable deal with excess light energy. The amount of trait. Total chlorophyll (P = 0.0051), carotenoids (P = 0.0266), and the ratio of total chlorophyll decreases during winter (Han chlorophyll to carotenoids (P = 0.0188) exhibited a positive relationship with greenness and Mukai, 1999; Ida, 1981) in both sun- after accounting for season and tree effects. In contrast, the ratio of chlorophyll a to and shade-exposed leaves (Han et al., 2004). chlorophyll b did not have an effect on greenness. There was a linear relationship This occurs in both wild-type and non- between total chlorophyll and carotenoid regardless of season (summer R2 = 0.94; winter 2 browning mutants (Han et al., 2003), thus R = 0.88) when pooled across 2 years. The observed correlation between chlorophyll and reducing the amount of energy absorbed. carotenoid content suggests they could be used interchangeably as predictors of The other mechanism is the conversion of greenness. There were large differences in rainfall between the 2 years that may have chloroplasts in sun-exposed leaves to resulted in additional variation. Furthermore, the climate in which the evaluation was rhodoxanthin-containing chromoplasts dur- conducted differs greatly from the native distribution of japanese-cedar occurring in ing winter to dissipate excess light energy China and Japan. as heat (Ida, 1981). In a study on 15-year-old japanese-cedar trees in Shizuoka Prefecture, Japan, Han et al. Japanese-cedar [Cryptomeria japonica diverse landscape situations. There are esti- (2004) reported accumulation of rhodoxan- (L.f.) D. Don] is a variable conifer that grows mates of over 100 different ornamental culti- thin in sun-exposed leaves beginning in up to 60 m tall in its native range. Wild-type vars (R. Determann, personal communication; January, reaching maximum levels in Febru- specimens are conical when young and be- Erhardt, 2005) with 45 of these grown in ary, decreasing significantly in March, and come cylindrical with age (Eckenwalder, 2009). the eastern United States (Rouse et al., 2000). falling to zero by April. However, timing of Japanese-cedar traditionally has been used as Japanese-cedars are native to the warm- discoloring in winter and restoration in spring screening or specimen plantings; however, temperate zones of south China and Japan. is highly variable and location-specific (per- there are a large number of cultivars display- In Japan, they generally are limited to north- sonal observation). Han et al. (2003) demon- ing varying forms and growth rates (Rouse facing slopes that receive 180 to 300 cm of strated that wild-type leaves that accumulated et al., 2000; Tripp, 1993) that may be used in rainfall per year (Tsukada, 1967). Japanese- rhodoxanthin maintained higher levels of pho- cedars perform well under a number of tosynthesis with lower levels of zeaxanthin- and environmental and soil conditions including antheraxanthin-dependent thermal dissipa- Received for publication 16 Sept. 2013. Accepted the hot, humid summers and heavy clay soils tion than mutants that remained green all for publication 28 Oct. 2013. of the southeast United States (Tripp and winter. The proposed role of rhodoxanthin is We thank Nancy Hand, Bruce Tucker, and Zhibing Raulston, 1992). As a result of this fact, to intercept a portion of incident light to help Xu for their technical assistance. japanese-cedars have been promoted as an 1Assistant Professor. maintain an appropriate balance among light 2Professor. alternative to Leyland cypress [·Cuprocyparis absorption, thermal dissipation, and photo- 3PhD Candidate. leylandii (A.B.Jacks. & Dallim.) Farjon (Farjon synthesis (Han et al., 2003). Japanese-cedar 4To whom reprint requests should be addressed; et al., 2002)], on which numerous problems also accumulated substantial levels of xan- e-mail [email protected]. now occur including bagworms (Thyridopteryx thophyll cycle pigments and lutein during 1452 HORTSCIENCE VOL. 48(12) DECEMBER 2013 winter (Han et al., 2003; Han and Mukai, the duration of the study was collected from collected to determine mean MC for each 1999). the same branches. Leaves were collected 8 individual (replicate) for each harvest date The overarching objective of the current Feb. 2008, 17 Aug. 2008, 9 Feb. 2009, and 5 using the formula {MC = [(initial weight – study was to identify an early predictor of May 2009 and frozen at –80 °C until analysis. dry weight)/initial weight] · 100}. winter foliage color (resistance to leaf brown- Temperature and precipitation data at the Color rating. Plants were observed within ing) in japanese-cedar as a screening tool for Tifton Campus for the duration of the study 1 week of the four leaf collection dates. Five identifying superior selections. Specifically, are included in Table 1. Supplemental irriga- evaluators assigned color ratings from 1 we assessed if quantitating pigments such as tion was used only at the time of new plant (very brown/yellow; off color) to 5 (very total chlorophyll (Ca+b), ratio of chlorophyll establishment within plots. green). Ratings of 3.5 to 4 would be consid- a (Ca):chlorophyll b (Cb), total carotenoids Chlorophyll and carotenoid extraction, ered acceptable for landscape use. All plants (Cx+c), and ratio of (Ca+b):(Cx+c) exhibited analysis, and calculations. Three subsamples were addressed from the southeast side, di- a strong relationship with greenness as mea- of leaf tissue were collected from the 12 rectly in front of flagged branches. Mean sured by visual color rating at the University individuals and Ca+b and Cx+c were extracted rating for each individual was calculated and of Georgia Tifton Campus (USDA Zone 8b; by grinding 85 mg leaf tissue three times used for statistical analysis. USDA-ARS, 2012). in 3.33 mL 80% aqueous acetone and the Design and statistical analysis. The ex- extract was transferred to a test tube and perimental design used repeated measure- Materials and Methods brought to a final volume of 10 mL. After the ments across winter and summer on each third grind in acetone, the leaf material re- individual with subsamples taken on the in- Plant material and growing conditions. maining was transferred to the test tube dividual branches. Relevant covariate informa- Single plants of the following 12 taxa of containing the extract and maintained in tion, chlorophyll and