ISHS Acta Horticulturae 394: Plant Bioregulators in Horticulture
TRANSLOCATION AND DISTRIBUTION PATTERN OF 14C-GA3 IN GEOTROPICALLY STIMULATED 'STARKING DELICIOUS' APPLE (MALUS DOMESTICA BORKH.) SHOOTS |
| Authors: | N. Sharma, K.K. Jindal |
| Keywords: | Geotropism, Tree orientation, 14C-GA3, Upper and lower side of shoot, Acropetal and basipetal transport |
| Abstract:
The physiological basis of geotropism in apple is not fully understood. However, it seems that enhanced flower-bud-formation on horizontal shoots, may be as a result of gibbrellin imbalance under the influence of gravity. In the active growing period, 14C-GA3 was fed to the mid leaf of 30 cm shoots from trees planted at 30°, 45°, 60° and 90° angles from the horizontal plane. Shoots were detached after 24 hours and radioactivity of GA3 in the upper and under side of shoots from above and below fed leaf and spurs was assayed. In all the geotropic stimulations, significantly higher concentration of labelled gibberellin was detected from the lower side of shoots compared to upper side. In vertical shoots, the concentration of labelled gibberellin in the upper and lower side of shoot was identical. GA3 moved acropetally as well as basipetally. There was more acropetal movement in non-vertical shoots compared to vertical shoots. However, vertical shoots had a higher basipetal movement than non-vertical shoot. The percentage recovery of GA3 radioactivity decreased with the increasing planting angle from 30° to vertical. On the basis of present findings, it appears that the increased flower-bud-formation on horizontal shoots may be attributed to the lower concentration of GA3 in the basal portion becuase of reduced basipetal transport. | |
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