| Popis: |
Ultimate strength of the xylem layer of the burley tobacco stalk ranged from 674 to 1453 kPa in tension and 1284 to 1943 kPa in shear. The ASTM standards for testing wood were used since the xylem layer has a structure similar to wood but were altered to meet the physical constraints of the stalk. The mean strength in tension was 946, 1120, and 1090 kPa for the early, normal, and late maturity, respectively. Mean strength in tension was higher for the lower stalk position (1164 kPa) than for the upper stalk position (999 kPa). Mean strengths for varieties KY 14, KY 17, and 21¥10 were 959, 1073, and 1214 kPa, respectively for tension and 1480, 1792, and 1618 kPa, respectively for shear. Maturity had no effect on shear strength. |
