Can Competitive Cultivars and Planting Depth Improve Success with Mechanical Cultivation in Table Beets?
Daniel Priddy1 and Daniel Brainard2
1Graduate Research Assistant, and 2Professor, Michigan State University
- Planting beets at 3-4 cm depth can delay emergence by 1-2 days relative to shallower seeding depths, potentially allowing for a longer window to stale seedbed.
- Cultivation-tolerant beets: Beet cultivars differ in their tolerance to both finger weeding and hilling.
- Weed-Competitive beets: Among cultivars evaluated, ‘Boro’ competed best with escaped weeds.
Direct seeded table beets ( Beta vulgaris) are among the most challenging crops to mechanically cultivate. Beet seed germination is not uniform and is sensitive to moisture (Taylor et al. 2002). In addition, beets are easily damaged by in-row cultivation or hilling until they are at the 4-leaf stage (Ascard & Bellinder 1996). Stale seed-bedding, which works well in crops like carrots is also challenging in beets because beet seedlings often emerge synchronously with weeds.
In a series of field and greenhouse trials, four beet cultivars—Boro (B), Chioggia Guardsmark (CG), Moneta (M), and Touchstone Gold (TG)— were evaluated for their tolerance to deep planting and mechanical cultivation as well as their competitiveness with escaped weeds.
In one set of experiments, seeds of each cultivar were sown at 1, 2, 3 and 4 cm depth and monitored for emergence and early growth under both greenhouse and field conditions. We hypothesized that deep sowing would facilitate stale seed bedding by delaying the time of beet emergence relative to weeds.
In a separate field experiment, the effects of cultivar, cultivation tool (finger weeder vs hilling disk) and weed competition (none vs escaped weeds) on weed and beet survival, beet yield and final weed biomass were evaluated. We hypothesized that cultivars with greater root biomass and root anchorage force would be more tolerant to finger weeders, while those with greater shoot biomass and height would be more tolerant to hilling.
In emergence studies, we found that under greenhouse conditions, B, CG and TG beet varieties could be planted at 3 or 4 cm depth to delay emergence by 1-2 days relative to shallower seeding depths, potentially allowing for a longer window to stale seedbed (Figure 1). However, under field conditions, emergence from greater depths sometimes resulted in either no difference in emergence timing or reduced total emergence and hence may be an impractical strategy under some soil conditions.
Figure 1. Effect of planting depth on emergence of ‘Touchstone Gold’ variety
In field cultivation studies, we found that cultivars differed in their tolerance to cultivation (CG >TG), as well as competitiveness with weeds (B>CG,M,TG). However, beet mortality was too low and beet characteristics too similar to adequately evaluate relationships between tool tolerance and plant traits. Although yield losses due to weed escapes following cultivation were not detected for any of the varieties, B had both the highest yield and lowest final weed biomass.
We have data on root:shoot partitioning and anchorage force at the time of cultivation, and will use regression analysis to identify traits associated with tolerance to both finger weeding (mostly uprooting forces) and hilling (tolerance to burial). The selectivity of each tool-cultivar combination will also be evaluated based on weed and crop mortality.
Ascard, J. and Bellinder, R.R.B., 1996. Mechanical in-row cultivation in row crops. In Proceedings second international weed control congress Copenhagen. (pp. 1121-1126).
Taylor AG, Goffinet MC, Pikuz SA, Shelkovenko TA, Mitchell MD, Chandler KM, Hammer DA (2003) Physico-chemical Factors Influence Beet ( Beta vulgaris L.) Seed Germination. Page The Biology of Seeds: Recent Research Advances. 433–440 p