Relationship Between the Starch Level at Budbreak and Current Shoot Growth in Abiesbalsamea L.

Abstract

Shading and transplanting procedures were used to vary springtime carbohydrate production and storage in 5-year-old balsam fir and Norway spruce seedlings. Current leader growth, and pre- and postbudbreak levels of starch, total sugar, and water in needles, stems, and roots were measured. Leader growth in seedlings shaded only before budbreak was similar to that in unshaded controls, although at budbreak the shaded seedlings had accumulated substantially less starch, the major form of reserve carbohydrate. However, seedlings shaded only after budbreak grew less than unshaded controls, despite similar starch contents at budbreak. Leader growth in seedlings lifted before budbreak and replanted when budbreak occurred in the field was the same as that in seedlings transplanted at field-budbreak, although the starch content was lower in the prebudbreak-lifted seedlings. The results indicate that current shoot growth in these conifers is independent of the level of reserve carbohydrate accumulated in the spring before budbreak.