PREANTHESIS INTERACTION OF CYTOKININS AND ABA IN THE TRANSPORT OF C-14 SUCROSE TO THE EAR OF WINTER-WHEAT (TRITICUM-AESTIVUM L)

The effect of the application of abscisic acid (ABA, 10(-4) mol . l-1), benzyl adenine (BA, 10(-6) mol . l-1), N6-m-hydroxybenzyl-adenosine (HBA, 10(-6) mol . l-1) and combinations of these cytokinins with ABA on the transport of C-14-sucrose into the developing kernels of winter wheat, their number and mass, was studied. Growth substances were applied in the period 10 to 5 days before anthesis and their effects were examined 4 and 18 days after anthesis on ears that were detached 10 days before anthesis and then cultivated on a complete nutrient solution. The stimulating effect of HBA on the transport of C-14-sucrose, number of kernels and their mass was higher than that of BA. ABA partly decreased the stimulating effect of cytokinins and reduced up to several days after anthesis the transport of C-14-sucrose to the developing kernels, their number and mass. The results revealed that a higher level of cytokinins in the period before anthesis could effectively interact with the inhibiting effect of ABA in that period and influence the accumulation of assimilates in the kernels.