Gibberellin elongation

These compounds were originally isolated from a parasitic fungus that causes excessive leaf elongation in nee plants. The mechanisms and applications of this group of compounds are described in Gibberellic Acid and Gibberellin Plant Growth Hormones. 

Gibberellin A3 has been shown to shorten the rest period of certain trees, shrubs, and seeds (5,7,10), and is the only substance known to stimulate elongation of resting epicotyls of tree peony (Paeonia stiffruticosa Haw.) seedlings (I). In the tubers of the potato (Solatium tuberosum L.), the rest period lasts from the time of tuber enlargement to 5 to 17 weeks after harvest, depending upon age,... 

Figure 2. Relation between sprouting of Red Pontiac potato tubers (A) and level of endogenous gibberellins in potato peels and buds during and after rest (C) as measured by internode elongation of maize mutant d5( B)...

Figure 2 shows the elongation of the first intemode of dwarf 5 (B) and the calculated changes in level of gibberellin-like substances (C) in relation to sprouting (A). The data of Figure 2, C, show that the level of endogenous gibberellins...

Figure 3. Gibberellin-like activity in peels of Red Pontiac potatoes during and after rest as revealed by intemoae elongation of maize mutants 1,3, and 5...

Most cold-dependent plants also possess a long-day requirement. The gibberellin treatment of these plants was usually conducted under long-day conditions, so that only the temperature-controlled block to flower formation was present. If the treatment was given under short-day conditions, only stem elongation was obtained it is evidently difficult to overcome the simultaneous presence of two blocks to flower formation. 

Galun (8) has recently reported similar results for monoecious cucumbers differing in the normal duration of the staminate stage. He demonstrated a close relationship between gibberellin-induced vegetative elongation and modification of flower sex expression (8). 

Note elongation of treated clusters and formation of shot berries Endogenous Gibberellin and Auxin... 

It has been demonstrated in California (29, 30, 33, 42, 43) and elsewhere (2, 5, 27, 46) that prebloom sprays of CA3 result in a loosening of compact-clustered varieties (Figure 2). Clusters elongate and/or more shot berries are formed. Why shot berry formation is stimulated is unknown. Gibberellin application may injure the pistil or stamens, or both. In this experiment the effect of... 

Prebloom sprays of gibberellin greatly elongate the clusters (Figure 2). The flower clusters are elongated, so that clusters of compact varieties are loosened, and some shot berries are formed. The loosening of compact-clustered wine grapes should prevent, or at least decrease, the amount of rot that may develop. 

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