LE3 .A278 2001

2001

Reekie, Edward

Acadia University

Master of Science

Masters

Biology

Biology

Four species of conifer were studied at both the interspecific and intraspecific levels to examine how variation in seed size affects early seedling growth response to elevated CO2. Elevated CO2 affected the large-seeded 'Picea abies ' more positively than the small seeded 'Picea rubens'. Differences in growth responses of the 'Picea' were likely due to differences in relative growth rate (RGR) within the first two weeks of growth. Elevated CO2 did not affect the growth of the ' Pinus' species. Intraspecific variation in seed size did affect growth, but there was no evidence of intraspecific differences in seed size on growth response to elevated CO2 in any of the four species studied. Contrasting growth responses to elevated CO2 of seeds of different size, at the interspecific and intraspecific levels, are explained in terms of seed reserves and the ratio of energy to mineral nutrient reserves within the seed. Specifically, if energy reserves are increased to a greater extent than mineral nutrients as seedsize increases, the CO2 response will decrease.

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