Evaluation of germination, growth and photosynthetic characteristics of rapeseed (Brassica napus L.) under different ultrasound treatments

In order to investigate the effect of intensity (40 and 59 kHz), power (60, 80 and 100 watts) and duration (2, 4, 6, 8 and 20 minutes) of ultrasound waves on germination, growth and physiological characteristics of canola (Ekapi cultivar), a factorial experiment was carried out as completely randomized design in the Seed Technology Laboratory of the Faculty of Agricultural Sciences of Shahed University in 2019. Germination percentage, germination rate, average time required for germination, weight and length index of seedling vigor, seedling length, seedling dry weight and some physiologic parameters including chlorophyll a, chlorophyll b, total chlorophyll, carotenoid content and relative water content were measured. The interaction of intensity, power of the device and duration of application of ultrasound waves affected all studied traits except germination rate, seedling dry weight and relative water content. The highest germination percentage of rapeseed seeds in the treatment composition was related to 59 kHz waves, 100 watts and 6 minutes with an average of 88.33%. The content of carotenoids, total chlorophyll, chlorophyll a and chlorophyll b were observed with an average of 22.57, 49.08, 22.62 and 26.47 μg/g fresh weight in the application of 40 kHz ultrasonic waves with a power of 80 watts for two minutes. Based on the results, it can be concluded that the use of ultrasound was able to improve the germination, growth and physiologic characteristics of rapeseed. Therefore, according to the conventional time-consumed seed dormancy breaking methods, the use of ultrasound as a new technology to break dormancy as an alternative to older methods is recommended.