Abstract:
The objective of this experiment was to determine the response of several cultivars of
soybean to gibberellins (GA3) application. Three soybean genotypes were grown in
plots of 3,2 m x 3 m with planting rate of 15 plants per m2. The experiment were
assigned in a split plot design with three replications, in which three rates of GA3 as
main plot and genotypes as subplots. The rates of GA3 concentration were 125 ppm,
250 ppm and control, and applied to the plant at 21 days after planting. Ten pods were
sampled every five days from randomly selected plants to observed seed dry weight. In
addition we observed seed dry matter accumulation rate, effective filling period, grain
yield m-2, and 100-seed weight.
The change of seed dry weight were very slow until 20 days after anthesis (DAA), then,
increased steadily until 40 DAA and reached physiological maturity at 50 DAA for all
varieties. The pattern of seed development was different among cultivars but almost
similar among the three GA3 concentrations exept for Grobogan, in which seed from
plants sprayed by 250 ppm GA3 showed lower rate than 125 ppm and control. Dry
matter accumulation rate of soybean cultivars sprayed by GA3 at a rate of 125 ppm
increased for around 30% for Anjasmoro and Grobogan compare to control and 250
ppm. Grain yield tent to increase by spraying GA3 at 125 ppm mainly for Argomulyo and Wilis and decreased beyond the concentration
