Relationship of Sugarbeet Fruit Size to Vigor of Commercially Processed Seed Lots and Cultivars1

Abstract

Sugarbeet (Beta vulgaris L.) seed is commercially processed and graded to several different fruit sizes. My objectives were first to determine the effect of fruit size on emergence potential and second to determine whether a laboratory packed sand test reliably measures these differences in emergence potential. Commercially processed and graded seed lots and cultivars were evaluated by the standard germination procedure, a laboratory packed sand test measuring percent emergence of seedlings through a 3.3 cm layer of packed sand (4% water wt/wt), and by field emergence trials. Field emergence was highly correlated with laboratory packed sand emergence (r = 0.92, 12 df), but not correlated with standard germination in tests involving three cultivars (‘GWH58,’ ‘GWH93,’ and ‘GWH115’) and four fruit sizes (2.4 to 2.8, 2.8 to 3.2, 3.2 to 3.6, and 3.6 to 4.0 mm diameter) in a 3 ✕ 4 factorial combination. Field and laboratory emergence increased with increase in fruit size from 2.4 to 2.8 to 3.2 to 3.6 ram; however, emergence of the largest fruit size (3.6 to 4.0 mm) was equal to or less than that of 3.2 to 3.6 mm size. Influence of fruit size on field emergence was not affected by planting date. Emergence of seed lots (four sizes per lot) of four cultivars (‘GWH45,’ GWH58, GWH93, and GWH115) was evaluated with the packed sand test in factorial combinations. Each cultivar had seed lots which were significantly different from one another. Emergence of GWH45, GWH93, and GWH115 seed progressively increased with increase in fruit diameter except for the largest size (3.6 to 4.0 mm) which was equal to or less emergence than that of the 3.2 to 3.6 mm size. GWH58 showed a similar trend except that seed size effects were not significant. No seed lot ✕ fruit size interaction was found. Thus all sizes of the superior emerging lots had better emergence than the corresponding sizes in the poorer lots. These tests show that fruit size must be kept constant when emergence potential of seed lots or cultivars is measured. The laboratory packed sand test, utilizing seed lot ✕ fruit size factorial combinations, effectively evaluated the emergence potential of seed lots of commercial cultivars.