Daucus carota subsp. carota

Traits evaluated: HUNDRED SEED WEIGHT (100SEEDWGT)

Method: This is the generic evaluation method that can be used for transferring hundred seed weights from the prod.nc7iv table to the prod.ob table. The prod.ob table is where the values for the descriptors are stored.

Accessions were planted in a randomized complete block design with two replications at the Hancock Research Station in Hancock, WI, in the summer of 2016 and 2017. One hundred seeds of each accession were planted in each 1-m plots. Canopy height was measured just before harvest with three measurements taken per plot. Harsh flavor was evaluated on a scale of 1 to 5 (with 5 being the least harsh, and 1 being the harshest) on at least three individual roots per plot after harvest in fall 2016.

The objectives of this study were to evaluate the response of diverse carrot germplasm to heat stress, identify heat-tolerant germplasm that may be used by plant breeders, and define the appropriate temperature for assessing heat tolerance in germinating carrot seed.

This study is the first field-based, multi-year experiment to evaluate shoot-growth trait variation over a 100-day growing season in a carrot diversity panel (N=695) that includes genetically diverse carrot accessions from the United States Department of Agriculture National Plant Germplasm System. This study provides the first broad-sense heritability estimates for early-season seedling vigor and early-season canopy coverage on a diverse collection. We also develop a method for characterizing flowering to identify accessions that are predominantly biennial, which could be incorporated into biennial breeding programs without substantially increasing the risk of annual growth habits.