Early Germination Response of Lodgepole Pine Seeds to Imbibition with a Commercial Extract of Ascophyllum nodosum

Increased stress resistance has been reported in various crops treated with Ascophyllum nodosum (L.) Le Jolis extract (ANE). Forest nurseries strive for vigorous and synchronous germination because it is key to producing uniform conifer seedling crops. Seeds of most conifer species require cool, moist stratification to break endodormancy before sowing, and stratification guidelines have been developed to optimize germination for each species. In conifer crops sown in greenhouses or outdoor compounds from early spring through early summer, controlling temperature and moisture during germination has always been crucial. Now, under a changing climate, hotter, drier weather is occurring during this period, resulting in heat and drought stress on germinants and reducing crop yields. We hypothesized that ANE would improve stress resistance in germinants, thus providing forest nurseries with a climate-change adaptation tool. We present only the initial phase of the study here. The objective of this trial was to determine if, and at what rate, ANE would improve germination response in lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.). The trial was conducted at Natural Resources Canada’s National Tree Seed Centre using seed collected from two natural stands in, respectively, southern British Columbia and central Yukon Territory. Seed was stratified for 21 d at 3 °C. We placed absorbent, multi-layered, cellulose wadding in rectangular, transparent plastic germination boxes and wetted it with solution, which was commercial ANE in distilled water at the following rates, listed in increasing concentrations: 1:2000, 1:1500, 1:1000, and 1:500. Distilled water alone served as control. We placed 25 seed of each seedlot in a box before placing the closed boxes in a germination cabinet at 30:20 °C day:night temperature, 8-h photoperiod supplied by fluorescent tubes, and constant 85% relative humidity, in accordance with International Seed Testing Association rules. We checked boxes at the same time daily, recording the germination status of each seed, scoring a seed as germinated at radicle length ≥ 5 mm. Germination was not evident in control and treated seed on day 3. By day 4, germination percentage for control, 1:2000, 1:1500, 1:1000, and 1:500 was 30%, 24%, 28%, 52%, and 28%, respectively. Germination percentage for control, 1:2000, 1:1500, 1:1000, and 1:500 was 80%, 88%, 84%, 92%, and 68%, respectively, on day 5. By day 6, 96% of control seed and 92% to 96% of treated seed had germinated. There was no difference in germination percentage for control and treated seed on day 7.