Effet du refroidissement local de la tige sur le transport du AIA exogene en provenance du bourgeon apical et sur la croissance des bourgeons axillaires.

Local cooling (1.5°C) of the stem (on 2 or 4 cm) a Vicia faba L. cv. Aguadulce for 15 h stops the exogenous IAA transport from the apical bud and causes a high accumulation of tracers above and at the level of the cooled zone. This clamping effect is reversed after removal of the cooling system. If the cooling system is maintained for 48 h, about 25% of the exported radioactivity passes the cooled zone. However, the percentage IAA transmitted decreases to about 6.6% if the cooled zone is sufficiently wide (4 cm) and the temperature lowered to 0.7°C±0.3°C. Using a cooling system of 4 cm (0.7±0.3°C) partially releases the lowermost axillary buds (ax1 and ax2) from apical dominance. Yet, the rate of growth of the axillary buds is generally lower than the growth rate after decapitation of the plant. [ABSTRACT FROM AUTHOR]