Certain growth retarding chemicals will temporarily suppress plant growth without ultimately affecting the rate of development and vigor of the ptant. The use of such growth retardants and inhibitors may be appropriate in forest tree nurseries in reducing seedling size, inducing dormancy, increasing hardiness and in delaying flushing.
An investigation was carried out to study the growth response of Douglas-fir seedlings to the growth retardant 2-chloroethyl phosphonic acid (ethrel) and the growth inhibitor maleic hydrazide (MH). Ethrel and MH were applied at five concentrations (0 to 1,000 ppm) to the root systems of eight week-old seedlings, using a sub-irrigated sand culture technique in the greenhouse for 44 days. Both ethrel and MH suppressed seedling growth, with MH being more effective. However MH was highly toxic to the seedlings at the higher concentrations, causing high mortality, and shoot apices and needles were chlorotic even at the lowest concentration. At the lower ethrel concentrations, no chlorosis and no mortality of seedlings were found. In contrast to MH, ethrel reduced root growth less than it reduced shoot growth.
A copy of the report by Dr. K-W Cheung titIed "Growth Response of Douglas-Fir Seedlings to Ethrel and Maleic Hydrazide", is available on loan (in British Columbia only) from the Library of i the B.C. Forest Service, Legislative Buildings, Victoria, B.C. V8V 1X5.
[Abstract contains full text of memo.]
BC Forest Service - Research Division. 1977. Growth Response of Douglas Fir Seedlings to Ethrel and Maleic Hydrazide. British Columbia Ministry of Forests, Lands, Natural Resource Operations and Rural Development. Research Memo (FLNRORD). RM15
Topic: FLNRORD Research Program
Keywords: FLNRORD, Research Memo, British Columbia
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