Allocation of current photosynthate and changes in tissue dry weight within northern red oak seedlings: individual leaf and flush carbon contributionduring episodic growth

Relatively little is known about the changing carbon allocation patterns in species with episodic growth cycles such as northern red oak (Quercus rubr a L.). To examine such changing allocation and growth patterns, northern re d oak plants were grown from seed in controlled environment chambers throug h four cycles of growth. (CO2)-C-14 was supplied to leaves of the first, se cond, or third flushes at different Quercus morphological index growth stag es within each flush, and the distribution of C-14 within the plant was ana lyzed. Carbon allocation from source leaves of the first and second flush w as primarily upward during the subsequent cycle of shoot growth and downwar d during lag and bud growth stages. All leaves within a flush did not respo nd the same. Upper leaves allocated most C-14-photosynthate upward during l eaf and shoot growth while lower leaves supplied more C-14 to lower stem an d roots. During the third and fourth flushes, differential allocation from leaves within a flush resulted in essentially equal upward and downward car bon allocation. Growth and allometric relationships reflected these changes in carbon allocation.