8Burden A N,Martin P A F. Chemical root pruing improves the root system morphology of coniferous seedlings[J]. Hort Sei ence, 1982,17(4) : 622 - 624.
9Halter M R,Chanway C P. Growth and root morphology of planted and naturally - regenerated Douglas - fir and Lodgepole pine[J]. Ann Set For,1993,50(1):71 -77.
10Hoitind H A J. Composted bark,alightweight growth medium with fungicidal properties[J]. Plant Disease, 1980,69(2) : 142 - 147.
