Post‐harvest respiration rates were measured on whole sugarbeet (Beta vulgaris L.) roots from 97 inbred and hybrid breeding lines to determine the magnitude of the genetic variability. Measurements were made between 50 and 160 days of storage at 5 C on 19 hybrids and inbreds grown at two locations; on eight hybrids and inbreds in 2 successive years; and on 76 inbreds.A high correlation (r=0.90**) existed between the loss of sucrose and respiration rate. The respiration rate of the entries varied between years and between locations, but relative rankings remained consistent (rs=0.87** and 0.81**, respectively). The Spearman's coefficient for respiration rates between locations was similar to those for yield (rs=0.77**) and sucrose content (rs=0.89**). Single‐cross hybrids respired at a lower rate than the midparent mean and, in several cases, lower than the lowest component inbred. A range of 2.5‐fold in respiration rate was found within the 76 inbreds. No correlation existed between sucrose content or root size and respiration rate. Sufficient genetic variability exists within sugarbeet genotypes to sustain a breeding program designed to develop low‐respiring breeding lines.
Economic improvement of sugarbeet (Beta vulgaris) field production and processing can be enhanced if traditional architecture of the sugarbeet is modified to a smooth root (SR) beet. Root shape of sugarbeet is a multigenic character and several generations of breeding are needed to reach any degree of homozygosity. In recent years conical-shaped SR beets have been developed in the eastern U.S. and in the Netherlands globe-sha ped beets have been deveioped by crossing table beet with sugarbeet foll owed by phenotypic recurrent selection. SR beets tend to have fewer fibrous rootlets near the soil surface than traditional grooved-root beets but rootlets still proliferate mainly along two vertical planes. SR testcross progenies have shown less taproot tip breakage than a commercial hybrid cultivar. Root yield of current SR genotypes and experimental hybrids has been eq ual or superior to that of commercial cultivars, but sucrose content has been 1-3 percentage points less. Soil tare for SR genotypes has ranged from 30070 to 70070 less than for current commercial cultivars with traditional architecture. Globe-shaped beets have lower soil tare than conical-shaped SR beets. However, SR beets bred with conical-shape are more desirable than globe-shaped roots for harvesting by current sugarbeet equipment, because globe-shaped beets grow more out of the soil, often are dislodged from the row when tops are flailed, and may not be picked up by the harvester.Additional
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.