Auxins and Gibberellin-like Substances in Parthenocarpic and Non-parthenocarpic Syconia of Ficus carica L., cv. King.
In the King cultivar of fig, the first crop is parthenocarpic, develops on previous year's growth, and a series of supernumerary ovules develops within the original ovules. The second crop, formed on current-season's growth, requires fertilization. To determine whether the 2 crops differed in types, and in patterns of concentrations of total ;free' auxins and acidic gibberellins, they were extracted from weekly fruit samples. Timing of the 3 peaks of total auxins and the single peak of gibberellins was identical in the 2 crops. The first auxin peak in both occurred at the end of fruit growth period I (first rapid growth period), the second shortly before the end of period II (period of slow growth), and the rise and fall in concentrations of the third peak accompanied the rise and fall of the fruit growth rate in period III. The end of period II was marked by the single gibberellin peak. Additional peaks before the first sampling dates, of auxins in the first crop, of gibberellins in the second, were indicated by high concentrations in the first samples and subsequent rapid decline. The same 4 individual auxins appeared in both crops. Auxins I and II were highest in concentration in the first total auxin peak of both crops. In the second peak of the first crop, auxins II and III were highest, whereas in that peak of the second crop auxins II and IV were highest. Qualitative differences in gibberellins occurred in the 2 crops. In general, auxin concentrations were higher in the first than the second crop, and gibberellin concentrations higher in the second. High concentrations of gibberellins coincided with low ones of auxins, and vice versa.
Lodhi
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F
Department of Pomology, University of California, Davis, California 95616.
Bradley
M V
MV
Crane
J C
JC