Cryopreservation of lipid-rich seeds: Effect of moisture content and cooling rate on germination

The effect of fast and slow cooling on germination of seeds from two Brassi caceae species (Eruca vesicaria (L.) Cav., Brassica napus L. var. oleifera (Moench) DC cv. Bingo) and cypselas from three Compositae species (Onopordu m nervosum Boiss., Onopordum acanthium L., Helianthus annuus L. cv. Viky) a t different moisture contents was studied. Seed lipid content (dry weight b asis) ranged from 15% (O. nervosum) to 41% (H. annuus). For each species, s eeds with four moisture contents were cryopreserved either by direct immers ion in liquid nitrogen or by previous cooling at 10 degreesC/min from room temperature to -50 degreesC. In three species (E. vesicaria, B. napus, and H. annuus) germination of air-dried (6.2-8.9% moisture content) seeds coole d by direct immersion in liquid nitrogen was not significantly different fr om germination of control seeds (air-dried, non-cooled). In the two Onopord um species the best response among cooling treatments was observed when air -dried seeds were slowly cooled.