Assessing Changes in Morphology, Fecundity and Disease Resistance of a Natural Coreopsis Leavenworthii Population During Seed Increase

To meet the demand from highway beautification and habitat restoration projects for <i>Coreopsis leavenworthii</i> planting stock, seed increase from natural populations is becoming common in Florida.  One of the ecological concerns facing seed increase is the potential of genetic shifts (changes) that might occur during this process.  To address this issue in <i>C. leavenworthii</i>, seeds were collected from a natural population in central Florida in 2006 and increased in both central and northern Florida for three generations from 2007 to 2009.  Then seeds from the natural population and the six increase populations were germinated and 525 individuals (75 per natural or increase population) were grown in summer and fall 2009 in a common garden study.  Plant height, plant dry weight, leaf morphological complexity, days to flower, ray flower size, disc flower size, seed production, and plant resistance to powdery mildew were assessed for each of the individual plants.  The mean value of each population was calculated and used to assess potential changes in these aspects during seed increase.  On average, plant height and dry weight was 72 cm and 108 grams, respectively.  Leaf morphological complexity was 3.4, on a scale of 1 to 6. Plants flowered within 112 days.  Flowers had 8 petals, and the size of the ray and disc flowers was 3.4 cm and 0.8 cm in diameter, respectively.  Each flower head produced 565 seeds on average.  Powdery mildew severity rating was 5.4, on a scale of 1 to 10. These results indicate no significant changes in all of these aspects during the three generation seed increase, or the genetic diversity in the natural population has been maintained.