The influence of light quality and carbon dioxide enrichment on the growth and physiology of seedlings of three conifer species. II. Physiological responses

摘要

Pinus banksiana,Picea mariana, andPicea glaucawere grown at 350, 700, or 1050ensp;mu;L∙Lminus;1CO2and either high or low red/far-red quantum flux ratios. After a 16-week, long day growth period, seedlings were subjected sequentially to short daylengths, then short days with low temperatures. Various physiological parameters were determined at the end of each treatment phase to monitor how those treatments influenced the onset of seedling dormancy. After the long day treatments, high ratios increased the total chlorophyll content and reduced the original level of chlorophyll fluorescence and the shoot total nonstructural carbohydrate content in very shade-intolerantPinus banksiana. In shade-tolerantPicea mariana, high CO2levels caused the main effects on these parameters while neither light quality or CO2had significant effects on them in shade-tolerantPicea glauca. Short days and low temperature induced a proportional increase in the partitioning of total nonstructural carbohydrate to the roots in all species and produced other species and treatment-specific responses.Keywords: light quality, CO2enrichment, chlorophyll fluorescenc