Effects of Ascophyllum nodosum extract application in the nursery on root growth of containerized white spruce seedlings

In this preliminary study, Picea glauca seedlings were root drenched with a commercial liquid extract of Ascophyllum nodosum in finisher fertilizer (8N-20P-30K) at the following rates: 1:500, 1:250, 1:125, and 1:75. Fertilizer alone served as control. Applications were made four or eight times over a period of 17 or 43 days, respectively. Compared with control, all rates reduced total root system length in mid October by 44-54%. After freezer storage and then growing under favorable conditions in spring for 21 d, the 1:125 and 1:75 rates increased the number of white roots emerging from the intact peat plug by 42 and 63%, respectively.