Preliminary investigation on the interaction between some physiological processes in donors and acceptors of assimilates

The interaction between physiological processes in donors and acceptors of 14C-assimilates was studied in sunflower and bean plants with temporarily limited supply of assimilates (shading a few days and then replacing in natural light conditions (NL)). An extended period of shading (4-7 days) affected growth of plants and reduced photosynthetic activity, especially in sunflower. The proportion of 14C-transported to roots decreased and that to the stern increased as an effect of preshading and did not significantly change in plants replaced in natural light conditions a few days before 14CO2-exposure. In preshaded blades and roots the rate of dark respiration decreased, but soon improved after a few days of NL conditions following the shading period. Absorption of 32P coincided with root respiration and sugar content in bean plant, in contrast to sunflower where 32P-absorption, calculated per l g of root dry matter in preshaded plants exceeded that in control ones