Department of Plant Sciences

Silicon (Si) is known to have beneficial effects on the growth and stress tolerance of some plants, especially rice. However, Si uptake varies very much between plant species, and it is not well known how widely spread the beneficial effects are. In particular, peat soils are likely to have very low Si levels, consequently low Si may be an issue in the boreal region, where these soils are common. We studied the effects of Si in a deciduous forest tree, silver birch (Betula pendula). One-year-old birch seedlings in peat plugs were planted in larger pots in unfertilized, unlimed peat. They were fed with a nutrient solution with or without Si for 7 weeks. Tests were done on leaf drying and leaf palatability to an insect herbivore, Epirrita autumnata. Plant parts were weighed after final harvest. There was a 6% increase on leaf growth in the Si fed plants. No effect on herbivory was observed. However, the leaves with no Si dried significantly faster after excision, which may have affected herbivory more than the Si as such. Further studies particularly in the water relations of silver birch would be of interest.