Accumulation and Utilization of Carbohydrate Reserves in Shoot Growth of <i>Pinus</i><i>resinosa</i>

Abstract

Evidence is presented which emphasizes the importance of food reserves and conditions controlling late-season photosynthesis (e.g. during bud development) to subsequent-year shoot growth ofPinusresinosa. By the end of August, after shoot elongation ceased, current 14 C-photosynthate was mobilized by roots, stems, and twigs. Much of the currently produced photosynthate accumulated as reserves in roots, stems, and twigs. When phloem blocks were applied in March behind the prior-year internode of defoliated shoots, thereby preventing phloem translocation of currently produced photosynthate from old needles to the buds, considerable shoot expansion still occurred, indicating utilization of reserve photosynthates of the prior-year internode.