Abstract:
Seventy percent of Indonesia’s soybean demands and consumption are met from imports,
and therefore, it is necessary to increase its local production. This study assessed the
effects of harmonic frequency and sound intensity levels on the opening of stomata, the
growth and yield of soybean. Experiments were conducted in a split plot design, with
frequency harmony (F4: 4 kHz, F8: 8 kHz, F12: 12 kHz) being the main plots and sound
intensity (A50: 50 decibels (dB), A80: 80 dB and A110: 110 dB) used as sub plots. The
results showed there was no significant effect of frequency and intensity on the measured
response (stomata opening). However, if they were compared with those at 0 frequency
and 0 intensity, the stomata openings were significantly different based on t-test at p =
0.05. This means the opening of stomata was affected by resonance. In general, the sound
level pressure attempted in the range of 50-110 dB had no effect on the width of stomata
opening, but it affected to the growth and yield of soybean. The best growth of the leaf
area and relative growth rate were in the
presence of sound waves at a frequency of 4
kHz. Likewise, the best result of the average
fresh weight of seed, dry weight of seed
and harvest index were at a frequency of 4
kHz sound waves. The leaf area, seeds fresh
and dry weight, and harvest index were also
significantly highest at sound intensity of 50
dB. Therefore, to improve the productivity
Istirochah Pujiwati, Nurul Aini, Setyawan P. Sakti and Bambang Guritno
964 Pertanika J. Trop. Agric. Sc. 41 (3): 963 - 974 (2018)
of soybean plants, exposure at a frequency
of 4 kHz and sound intensity of 50 dB,
followed by an application of leaf fertiliser
according to recommended dosage is the
best combination of treatment in growing
soybean in Indonesia.
