Growth and development of Pinus sylvestris L. seedlings were determined for 3 photoperiods, 2 temperatures, and 7 seed sources, ranging from Turkey to Germany. (1) Growth and development were affected appreciably by photoperiod, temperature, seed source and their interactions; (2) magnitude of the variation among seed sources appears to justify a more comprehensive evaluation of within-species variation to find suitable variants for plantings in Iowa; (3) photoperiod and temperature appear to be two environmental factors important in the process of natural selection within the species, even over the limited natural range of seed sources studied; and (4) some criteria have been obtained to test the feasibility of early selection of variants for field plantings in Iowa.
Document Type: Journal Article
Professor, Dept. of Forestry, Iowa State University