Agronomic Comparison of Different Types of Smooth Root and " Soil Free" Sugarbeet

FieJd experiments were conducted for 3 years in Michigan to compare growth characteristics and agronomic performance of sugarbeet genotypes differing in their taproot architecture. Genotypes were MH E4, ACH 176, and ACH 185, aU commercial hybrids with standard grooved taproots; SR87, a conical-shaped smooth root (SR) genotype; A90MM, a gl obe-shaped SR experimental triploid hybrid from the Netherlands; and Univers, a European commercial variety that has low soil tare at harvest. A90MM differed from aU other genotypes, having only about 50070 of the root underground. Averaged over years, root yield for SR87 was si gnificantly greater than for A90MM, Univers, and MH E4. Sucrose content for SR87 and A90MM was 1-2 percent of root fresh weight lower than for the U.S. commercial varieties. SR87 was equal to the commercial varieties and greater than A90MM in sucrose yield per hectare. Little difference was observed in clear juice purity. A90MM had about half the soil tare of SR87 and Univers and about one-fourth that of the standard grooved root varieties. A90MM had the disadvantage of often being dislodged from the row when tops were removed with a rotobeater. With current sugarbeet defoliators and harvesters, conical-shaped smooth root beets would have the more desirable architecture.