From www.mgr.net: Root growth potential of scotch pine seed sources and its relationship to field performance James E. JOHNSON, Richard E. KREH, John L. TORBERT, and Peter P. FERET School of Forestry Wildlife Resources Virginia Polytechnic Institute and State University Blacksburg, Virginia 24061, USA Paper read at the Northeastern State, Federal and Provincial Nurserymen's Conference, Montreal, Quebec, July 24 to July 27, 1990. Abstract: Commercially available Scotch pine seed sources were studied to determine root growth potential (RGP), field performance, and the relationship between RGP and field performance in the Mountain, Piedmont, and Coastal Plain physiographic regions of Virginia. RGP's ranged from 41 new roots for the Lower Austria seed source to 7 new roots for the Burgos seed source. Seed sources varied in field performance across the state. Overall, second year survival was greatest in the Mountains (79%), and significantly lower in the Piedmont and Coastal Plain (64% each). The seed sources with the highest and lowest RGP's also exhibited the highest and lowest field survivals and field performance as measured by volume increase. Key words: root growth, containerized seedlings, tree planting, Christmas trees. Résumé Le potentiel de croissance racinaire des provenances de graines de pin sylvestre et ses rapports avec leur rendement sur le terrain. On a etudie les diverses provenances de graines de pin sylvestre disponibles dans le commerce afin d'evaluer leur rythme de croissance racinaire (RCR), leur rendement sur le terrain ainsi quo la relation entre celui-ci et le RCR, dans les trois regions physiographiques de la Virginie : montagneuse, de piedmont et de la plaine cOtiere. Le RCR a varie de 41 racines nouvelles pour la provenance de Basso Autriche a 7 racines nouvelles pour la provenance n Burgos A travers tout l'Etat, les rendements sur le terrain ont varie selon les provenances. Dans /'ensemble, le faux de survie pour la deuxieme annee a ete superieur dans la region montagneuse (79 %) mais significativement plus faible dans le piedmont et la plaine c6tiere (64 % chacune). Les provenances montrant les RCR les plus hauts et les plus bas presentaient aussi les faux de survie les plus forts et les plus faibles. Mots-cles : croissance racinaire, recipients, plantation, arbres de Noel Introduction: Production of seedlings for Christmas trees in the U.S. is increasing each year. The National Christmas Tree Association estimated the 1988 planting at over 73.5 million seedlings, an increase of nearly 12% since 1984. With Scotch pine (Pinus sylvestris L.) as the major Christmas tree species, nursery producers are interested in seedling characteristics and quality differences among the major seed sources and varieties. Variability in growth, morphological features, and pest resistance of numerous Scotch pine varieties have been studied in the north central U.S. (WRIGHT et al. 1 966); and currently many varieties are available from commercial seed dealers and nurseries throughout the country (Noecker 1988). The concept of root growth potential (RGP), introduced by Stone (1955), has emerged as a useful method of estimating the physiological status of seedlings. Root growth potential is defined as the ability of a tree seedling to initiate and elongate roots when placed into an environment favorable for root growth (Ritchie 1985). This study was established to compare the growth and phenotypic characteristics of 15 commercially available seed sources of Scotch pine, with particular reference to suitability for Christmas tree production in Virginia. This paper deals with the establishment phase of the Scotch pine plantations, and reports potential (RGP), field performance and discusses the overall relationship between RGP and field performance. Methods: Stock Production: Seed was obtained from commercial sources for 15 Scotch pine seed sources, stratified at 4°C for 45 days, then sown, three seeds per container, in April, 1986. Following germination seedlings were thinned to one per container. Seedlings were grown in 65 cm 3 container cells in a 50:50 Promix BX/sand mix in the greenhouse under natural light supplemented with artificial lighting to 11:00 p.m. Seedlings were periodically irrigated, fertilized with a complete liquid fertilizer, and treated with a commercial fungicide. During November, 1986, the seedlings were placed under natural light to induce dormancy and then placed in an outdoor slat house in January, 1987. 149 RGP Test: During March of 1987, 30 seedlings of each seed source were removed from the containers and all potting medium was washed from the root systems. The seedlings were placed in a well-aerated water bath held at a constant 18°C temperature for 21 days. Day length was supplemented by artificial light to 16 hours per day. Following the test period the seedlings were removed from the water bath, and all new roots were counted. RGP was expressed as the total number of new roots which grew during the test period. The RGP test was not conducted on the Musser Forest's seed source due to inadequate germination of this seed source leading to an insufficient number of seedlings. The entire RGP test was repeated three times to coincide with the beginning, middle, and end of the planting season. Field Planting: Sites for field planting were selected within each of the three physiographic regions of Virginia. Accordingly, three sites were located in the Coastal Plain, Piedmont, and Appalachian Mountains . All of the planting sites were previously abandoned fields, with a mixture of annual grasses and broadleaved weeks. Planting sites included a wide variety of soil and cli matic conditions. Soil testing data for the surface 15 cm of each of the planting sites is provided in Table 1. The soils varied in texture from sandy loams to loams, and included a range of soil fertility levels. Climatic characteristics vary greatly throughout the study area. In the Mountains the average temperatures range from –7°C in winter to 28°C in summer, with an average annual precipitation of 102 cm. The normal growing season is about 129 days long. Climatic conditions in the Piedmont vary considerably, but on the average the temperatures range between –3°C in winter and 31°C in summer. Total annual precipitation averages 110 cm, and the growing season is about 190 days long. In the Coastal Plain average temperatures range from 0°C in winter to 30°C in summer, with the average precipitation totaling 113 cm. The growing season in the Coastal Plain is the longest in the state, averaging 214 days. The plantations were established during March and April, 1987, by hand-planting the containerized seedlings in hand-scalped planting spots. In each plantation, each seed source was represented by 15 seedlings planted at random locations on a 2 m by 2 m grid (i.e. single-tree plots). Plantation Maintenance and Seedling Measurements: In all plantations weed control was accomplished using a combination of fall glyphosate applications and spring simizine applications, both applied as directed sprays. In some plantations additional weed control was accomplished by mowing. In all plantations the seedlings were kept in a free-to-grow condition, above the grass and herbaceous competition. Woody brush competition was not a factor in any plantation. After the 1987 and 1988 growing seasons, all plantations were checked for survival, and seedling heights and ground-line diameters were measured. Results and discussion: RGP Difference Between Varieties RGP varied considerably between the 14 Scotch pine seed sources tested. The Lower Austria and Belgium sources had an RGP of 41 and 35 new roots, respectively. The seed sources with the lowest RGP included Eastern U.S., Turkey, Guadarrama, Guadalaraja, and Burgos, ranging from 16 to 7 new roots . All other varieties had an RGP of between 17 and 29 new roots. Differences in RGP between species, grown under identical test conditions, can be dramatic (RITCHIE and DUNLAP 1980). Likewise, differences among seed sources and among families within a species have also been reported (RITCHIE 1985, SUTTON 1983, DEWALD et al. 1985). Generally, RGP is thought to be under strong genetic influence. Even when differences in RGP between provenances of eastern white pine (Pinus strobus L.) were not significant, differences in RGP between individual families were apparent (JOHNSEN et al. 1988). Due to the great geographic variation of the natural range of Scotch pine, it is highly likely that different seed sources have different chilling requirements necessary to break bud dormancy. There is evidence that the peak of RGP is related to the dormancy cycle, with the peak occurring in midwinter, followed by the main root growth activity in early spring, which then declines with the advent of shoot growth (RITCHIE and DUNLAP 1980). The chilling conditions provided in this experiment may have been optimum for some of the seed sources, 151 I 1 A 153 but not for others. Geographic variation in chilling requirement within a species has been observed (RITCHIE and DUNLAP 1980), and may partially ex- - plain the wide variety of RGP's reported here. Field Performance Survival over all physiographic regions ranged from 42 to 78 percent with the lowest one being the Burgos seed source which also had the lowest RGP. Overall seedling survival was greatest in the Mountains (79%) as compared to the Piedmont and Coastal Plain (64% each). Within each of the regions there were differences among seed source in survival. On the Coastal Plain a group of 11 seed sources had the highest survival rate, ranging from 58 to 84%. In the Mountains this same group, plus the Eastern U.S. variety, had the highest survival, ranging from 71 to 91%. Survival in the Piedmont was highly variable, ranging from 36 to 73%, with no significant differences between seed sources. On the Coastal Plain the French Auvergne and Lower Austria sources were the top survivors; in the Mountains the Lower Austria and Central Massif sources survived the best, and on the Coastal Plain the Casadeen Massif, Turkey, Riga, and French Auvergne sources topped the list . . Although these variables are not growth variables per se, they are indicative of the overall vigor of the seedlings and consequently the degree to which they are adapted to the planting sites. Since the containerized seedlings were all similarly sized at the time of planting and had all been growing for two seasons, second-year seedling dimensions, prior to shearing, provide a good measure of seedling establishment. The largest seedlings in terms of volume were produced by the Lower Austria seed source when averaged over all planting sites and corresponds to the one with the highest RGP . On a physiographic basis, the largest seedlings grew in the Mountains, followed by the Coastal Plain and the Piedmont . Within each region there were significant differences between sources in seedling height, diameter, and volume. Across all regions the Lower Austria source stands out as the fastest growing. This source also survived well throughout the state. Previous Scotch pine seed source studies have shown that seedling growth is closely correlated with origin of seed (KING 1965a, 1965b, WRIGHt et al. 1966). In the north central U.S., Scotch pine seed sources from central Europe grew most rapidly, while northern varieties were the slowest growing. Our study contains no Scandinavian seed sources; however, the largest seedlings tended to be from central European locations. WRIGHT et al. (1966) found that Scotch pine sources often perform similarly across a wide variety of sites, and that the seed source X site interaction only accounted for about five percent of the variation in seedling height. The varieties in this study also tended to perform similarly throughout the regions. For example, the Spearman rank correlation coefficient for seedling volume between the Mountain and Piedmont sites was 0.82. The largest seedlings in the top three sources in the Mountains (Lower Austria, Belgium, and Bugenland) were also the largest in the Coastal Plain and Piedmont. All sources tended to perform poorly on the Piedmont. Climatically this region is intermediate between the Coastal Plain and Mountains; however, the soils tended to be much more similar to those of the Mountain sites. Unfortunately this region experienced unusual drought periods in the first and second year of the study which confounded performance similarities. WRIGHT et al. (1966) found the best growth of Scotch pine seedlings on sandy loam to loam soils. It may be that the combination of climate and soils found in the Piedmont are the least desirable conditions for Scotch pine survival and growth. Relationship Between RGP and Field Performance Numerous studies have shown high RGP to be correlated with good field performance for a number of pine species, including loblolly pine (Pinus taeda L.) (FERET and KREH 1985), ponderosa pine (Pinus ponderosa Dougl. ex Laws) (STONE 1955), jack pine (Pinus banksiana Lamb.) (SUTTON 1987), and lodgepole pine (Pinus contorta Dougl. ex Loud) (BURDETTE et al.1983). Presumably RGP is positively correlated with seedling characteristics important to survival and growth during the first year following planting. Alternatively RGP may be the direct cause of survival and early growth because of its relationship to root-soil contact. RITCHIE (1985) indicated that with Douglas fir (Pseudotsuga menziesii (Mirb.) Franco), RGP may be related to cold and stress resistance, while CARLSON (1986) indicated that 157 NICHOLS, T. J. 1989. Shearing. p. 79-103 In Johnson, J. E. (ed.) Christmas Tree Production Manual. VA Coop. Ext. Serv. Pub. 420-075. VA Polytech. Inst. and State Univ., Blacksburg, VA. NOECKER, N. 1988. Scotch pine varieties, characteristics, and performance. Christmas Trees 16 : 34-41. RITCHIE, G. A. 1985. Root growth potential : principles, procedures, and predictive ability. p. 93- 105 In Duryea, M. L (ed.) Evaluating Seedling Quality : Principles, Procedures, and Predictive Abilities of Major Tests. Oregon State Univ., Forest Research Lab., Corvallis, OR. RITCHIE, G. A., and J. R. DUNLAP. 1980. Root growth potential: its development and expression in forest tree seedlings. N.Z. J. For. Sci. 10 : 218-248. STONE, E. C. 1955. Poor survival and the physiological condition of planting stock. For. Sci. 1 : 90-94. SUTTON, R. F. 1983. Root growth capacity: relationship with field root growth and performance in outplanted jack pine and black spruce. Plant and Soil 71:111-122. SUTTON, R. F. 1987. Root growth capacity and field performance of jack pine and black spruce in boreal stand establishment in Ontario. Can. J. For. Res. 17 : 194-804. WRIGHT, J. W., S. S. PAULEY, R. B. POLK, J. J. JOKELA, and R. A. READ. 1966. Performance of Scotch pine varieties in the North Central

Irregular pyramid shape in its youth often used as a Christmas tree. Open with a round or flat top with widespreading branches as it matures.Needles are 1-3" long. Orangish brown bark. Extremely adaptable to various soils