Inhibition of black spruce seedling growth by forest-floor substrates of central Newfoundland

Abstract

The objective of this study was to determine if seedbed substrates consisting of F and H organic matter and Ae and Bf mineral material inhibited seed germination and subsequent seedling growth of black spruce. The study was conducted with seedbed substrates collected from eight pure blackspruce stands of four age classes (15, 30, 45 and 60 years) in central Newfoundland. No significant effect on percentage germination or primary shoot growth of seedlings was obtained when grown on F and H organic matter, Ae and Bf mineral material. However, growth and development of primary roots was significantly reduced in the F and H organic matter and Ae mineral material compared to the controls (washed sand). The inhibitory effect increased with stand age. The affected seedlings did not produce normal primary roots with root hairs. The primary root cells of the affected seedlings were significantly broader and shorter compared to the control seedlings. Mineral material from the Bf horizon did not have any significant effect on primary root growth of black spruce seedlings.