ProCrop

Effect of Row Spacing and Plant Population on Oil Seed Sunflower

Row spacing and plant population effects were more evident when growing conditions enabled greater plant development and character expression. Row spacing (table 1) and plant population (table 2) effects on seed yield were observed at four of the six tested environments. At the Casselton and Minot 1998 environment production from the 12 inch row spacing was greater than production from the traditional 30 inch row spacing. Greater yield at this row spacing, 12 inch, under favorable growing conditions improves yield potential and helps balance the risk of potential weed control problems. For drier environments where yield increase from narrow row spacings are not as likely, growers should carefully evaluate seed control concerns. The decision on which row spacing to use involves more than potential yield increases and weed control issues. Availability of planting equipment, time constraints, harvest timeliness, and other agronomic concerns also influence this decision. All factors should be considered when producers make this decision.

Plant population influences were also more apparent at the Casselton environments where yield increased as plant population decreased. However, the opposite response to plant population was observed one year at Minot. At the Minot 1998 environment, yield was greater at the highest plant population. Seed oil concentration and head diameter also become important characteristics as plant population decreases. Excessively low plant populations can reduce crop value by reducing seed yield and seed oil concentration. Large heads, from low plant populations, may require longer to dry down and be difficult to harvest. Seed moisture differences caused by plant population were not observed at harvest in this study. Again the decision on what plant population to grow involves consideration of more determinants than just seed yield, although seed yield is the principle factor economic yield is based on.

Authors B.L. Johnson, M.E. Zarnstorff and J. F Miller. Source. Proceedings of 21st Sunflower Research Workshop Dgs. 183-192

Table 1. Mean seed yield, seed oil concentration, seed weight, days to flowering, plant height, head diameter, and seed moisture at four row spacing and four environments averaged across two hybrids and three plant populations.

*10% moisture basis

** Days from planting to R5.1

+ At harvest

Table 2. Mean seed yield, seed oil concentration, seed weight, days to flowering, plant height, head diameter, and seed moisture at three plant populations and four environments averaged across two hybrids and four row spacings.

*10% moisture basis

** Days from planting to R5.1

+ At harvest

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