Time of seed collection and germination in rocket, Erucavesicaria (L.) Cav. (Brassicaceae)

The increasing importance of rocket Erucaspp. as a leaf and oil crop, and especially as a Fourth Generationvegetable, calls for a better understanding of several basic aspectsof its biology. Knowledge on seed germination behaviour is necessaryto optimize the management of the plant in the field and inseedbanks. Seed germination of several samples of rocket was assayedin the laboratory under different incubation conditions. Germinationin the two studied populations was fairly high, ranging from68% to 96%. However, remarkable variation was foundwithin one of them according to the date of collection of the sample,ranging from 78–96% for those collected in summer(LG1 and LG2) to 21–29% for that collected inautumn (LG3). Neither time of storage nor GA₃treatments had any significant effect on this low percentage, whichcould only be significantly improved with scarification, up to47% by dry heat and up to 66% by immersion in liquidnitrogen. Dormancy and low seed viability probably originating fromeffects of environmental factors during seed formation and maturationseem to play a role in the low germination percentage of sampleLG3.