ENHANCING SEED GERMINATION OF FOUR CROP SPECIES USING AN ULTRASONIC TECHNIQUE

A laboratory experiment was conducted to determine the effect of ultrasound (US) treatment on seed germination of chickpea, wheat, pepper and watermelon. All tests were carried out at 40 kHz in a water bath ultrasonic device varying two factors, treatment duration (5, 10, 15, 30,45 or 60 min) and germination temperature (15 or 20 degrees C). Parallel tests were run in which seeds were soaked in water without sonication in order to eliminate the effect of water from US test results. The effects of US on seed germination varied between crops and were more obvious on germination speed, expressed as germination rate index (GRI), rather than on germination percentage (GP). In particular, US treatment significantly increased the GRI of chickpeas, wheat and watermelon, resulting in a maximum increase of 133% (at 15 min), 95% (30 min) and 45% (5 min), respectively, above control seeds. The beneficial effects of US on the GRI of these crops were observed at both 15 and 20 C, suggesting that US treatment offers a practical priming method to overcome the slow germination that may occur at low temperatures. Water-soaking treatment improved the GP of both chickpea and pepper seeds by 59 and 24%, respectively, compared to the control but neither water nor US had any positive effect on pepper GRI. Post-treatment measurement of moisture content of these seeds produced variable results depending on crop species :And US treatment duration. Results of this research indicated that US treatment effectively enhanced speed of germination of chickpea, wheat and watermelon seeds. This increase in speed of germination may improve early field establishment of these crops in the semiarid Mediterranean region and thus needs further investigation. The US technique may also be very useful for plant propagators in nurseries to achieve fast seedling establishment of watermelon.