Effect of Silver-Sheet and Figaron on Flower Production, Abscission of Reproductive Organs, Yield and Yield Components in Soybean (Glycine max L.)

Both silver-sheet (a light reflector) and Figaron (a phytohormone), used individually, influence the production and abscission of reproductive organs during the reproductive stages of soybean. The combined use of silver-sheet and Figaron, however, has a much larger effect on production and abscission than the use of each alone. Experiments were conducted in the field at Niigata University, Japan, to investigate the light intensity at the canopy attributable to light reflection by silver-sheet and the individual and combined effects of silver-sheet and Figaron on reproductive abscission, yield and yield components of soybean. The field study was conducted on a sandy loam soil at 25 and 16 plants m^?2 in 1999 and 2000. The results of the 2-year study indicated that Figaron had no effect on growth parameters, whereas silver-sheet had an effect. Flower production in the Figaron and Figaron + silver-sheet treatments tended to be lower than in the control and silver-sheet treatments. Silver-sheet increased the light intensity in the lower canopy of soybean through reflection, and thus the percentage of reproductive abscission in the lower canopy was lower in the silver-sheet treatments than in the other treatments. Greater pod set was observed in the middle and upper canopies than in the lower canopy in the Figaron treatments. Therefore, total pod set or pod number was greater in the combined silver-sheet and Figaron treatments. Yield and its components were greater at higher plant densities and tended to be greater in the combined treatments of silver-sheet and Figaron. The increase of yield components in the combined silver-sheet and Figaron treatments was believed to be a result of favourable light conditions and source–sink alterations in the canopy induced by Figaron.