Grading Ponderosa Pine Seedlings for Outplanting According to their Root Volume1

Abstract

Abstract In probably one of the first studies of its kind, three different seed sources of 2 + 0 ponderosa pine (Pinus ponderosa) seedlings were graded on the basis of three root-volume categories (< 4.5, 4.5-7, and > 7 cm³) and out-planted to determine differences in survival and growth over 1 and 2 growing seasons, examine the relationship of seedling field height to nursery root volume, total fresh weight, diameter, and height over the same period, and observe differences in nutrient uptake by seedlings among the three categories over 174 days in the field. Seedling survival was good over the two growing seasons. Seedlings graded to the largest root-volume category were significantly taller and grew significantly more than those in the two smaller categories over the 2 years. Nitrogen and potassium contents decreased over the growing season, those seedlings with larger root volumes showing the greatest decrease. The results suggest that root volume has potential as a useful criterion for grading seedlings. West. J. Appl. For. 6(1):11-15.