Influence of Biophysical Priming on Seed Germination and Yield on Two Landraces of Lemon-Balm (Melissa officinalis L.)

Abstract

The aim is to study the effects of physical seed priming on germination and yield of lemon balm. Laboratory and pots experiments were conducted as factorial based on completely randomized design. The treatments are magnetic field with 75 mT for 10 and 15 min durations; laser light with 2 mw.cm -2 for 20 min; ultrasonic wave with physiotrapy device for 20 min; cs-gamma ray for one hour in lead cell, and control that were applied on two landraces of lemon balm ('Karaj' , 'Esfahan'). Then in laboratory with use of special paper and pure water the seeds were cultured in petri-dishes and were putt in germinator with 19°C temperature for 8 days and were counted daily. Some parts of primed seeds were stored in normal condition for 6 months and were cultured in laboratory condition. All the primed seeds were farmed in pots. Three months later the plants were harvested in first blooming level and dry weight and essential oil percentage were measured. Results showed that the influence of various treatments on germination percentage and germination rate were significant. Magnetic field treatment (15 min) showed the highest positive effect on percentage (86%), and rate. The length and weight of seedling in magnetic field treatment were the highest in comparison with other ones. Considering physiological characteristics, the higher Leaf Area Ratio and Leaf Area Index were seen in magnetic field. Effect of different treatments on plant height, biomass dry weight and essential oil concentration was significant.

Thermal Effects of Laser Irradiation on Maize Seeds

“…The variations of temperature will be a function of the seed characteristics, as well as the exposure time to the laser beam (Hernandez et al, 2010). The exposure times to red laser irradiation (wavelength from 618 to 780 nm) have ranged from milliseconds, seconds, minutes to hours using several lasers (Aladjadjiyan, 2012;Hoseini et al, 2013;Khalifa and Ghandoor, 2011;Metwally et al, 2013;Mohammadi et al, 2012;Podleśny et al, 2012). Therefore, the objective of the present study was to determine the evolution of the temperature in maize seeds (Zea mays L.) when LILI was applied during 60 s and after 60 s of laser off, evaluating the temperature variation by using a thermal camera.…”