Tk. Golovko et Gn. Tabalenkova, UTILIZATION OF ASSIMILATES FOR GROWTH AND RESPIRATION IN LOLIUM-MULTIFLORUM LAM PLANTS, Russian journal of plant physiology, 41(5), 1994, pp. 629-634
Uptake, distribution, storage, and reutilization of C-14-assimilates w
ere studied to evaluate the utilization of C-14-products for growth an
d respiration in intact and defoliated (by mowing) Italian ryegrass (L
olium multiflorum Lam.) plants. The long-term changes in C-14 losses r
evealed a two-phase pattern. Rapid C-14 losses in the first hours afte
r (CO2)-C-14 assimilation indicated a preferential utilization of ''yo
ung'' assimilates for respiration. The slow C-14 losses proceeded for
some weeks and apparently coincided with C-14 incorporation into the s
tructural and reserve compounds. In the source-sink system of Italian
ryegrass, the transitory assimilate reservoir was located in the culms
. Stored C-14 compounds were rapidly reutilized only by the plants aft
er defoliation, but remained almost unutilized in the intact plants. C
-14-reutilization was accompanied by additional respiratory expenditur
es related to biomass de novo production. The C-14-fraction withdrawn
from transitory reservoir and used for the respiration during the regr
owth after mowing was close in size to C-14-fraction used for the resp
iration of intact plants after (CO2)-C-14 assimilation.