Seeds were sterilised for 1 min by immersion in ethanol. Then the seeds were steeped in deionised water in ratio 1:10 (m/v) for 12 h. After pouring off the soaking water, the seeds were spread on sterile stackable trays (three for one species) and were washed twice a day using deionised water to avoid microbial growth. Sunflower seeds were initially peeled of their shells.