Abstract:
Since the productivity of soybean in Indonesia is still low, a new innovation is needed to improve it.
The objectives of this study are to determine a pattern of the stomatal opening of soybean’s leaves
which exposed by high-frequency sound waves with different duration time and age of soybean
plants. This study was carried out at the Experimental Farm Agriculture Faculty and Biology
Laboratory of Science Faculty of the Islamic University of Malang, East Java in April to August
2013.The first factor was duration time of the exposure which consist of three levels: 20 minutes (D1),
40 minutes (D2) and 60 minute (D3).The second factor was the age of the soybean which consist of
three levels: 15 days after planting (dap) (A1), 25 dap (A2) and 35 dap (A3). The soybean plants were
exposure by the 5000 hertz frequency. The variables measured consisted of stomatal opening width,
plant height, leaf area, fresh weight of pods, fresh weight of seed, oven dry weight of beans and
harvest index. Increase of the duration time of exposure of high frequency sound waves by 20 to 60
minutes, tends to decrease the width of stomatal opening. The treatment of duration of exposure by
40 minutes at the age of 15 dap had the highest soybean grain yield by 24.10 g.plant-1
, equivalent to
3.93 ton.ha-1
. The relationship between the widths of the stomatal opening with soybean production
showed no significant correlation. The results of this study suggest that maintaining stomatal opening
at optimum width through the manipulation of high-frequency sound waves will increase the yield of
soybean plants.
