Flowering, Abortion, and Yield of Early-Maturing Soybeans at Three Densities
1978
Dominguez, Carlos | Hume, D. J.
Attempts to extend the northern limits of soybean [Glycine max (L.) Merr.] production in North America are hampered by low yields. The earliest-maturing genotypes are small, short-statured plants. Their size suggests that yields could be increased by raising the plant population. In these trials, the early-maturing genotypes, ‘Fiskeby V’, ‘052–903’, ‘Altona,’ and ‘Vansoy’, were grown in 30-cm row widths at 40, 80 and 120 plants/m₂ in 1975 and 1976 in a silty clay loam (Aquic Hapludalfs). The objective was to determine the influence of seeding rates on flower and pod production, abortion, yield components, and seed yield. Total flowers produced and initial and final numbers of pods per plant were decreased at high densities. The percentage of reproductive structures aborted also increased. More abortion occurred during the flowering period than post-flowering period. The number of pods per plant was the yield component most affected by increasing density. The planting to flowering period, duration of flower production, number of seeds per pod, and seed size were cultivar characteristics not affected by density treatments. Final seed yields averaged 2,740 kg/ha over the 2 years. Seed yield increased by about 190 kg/ha when density was increased from 40 to 80 plants/m₂ and by another 100 kg/ha when density was increased from 80 to 120 plants/m₂. These responses represented only about twice the extra seed planted. The middle one-third of the plants on a plant height basis produced an average of 44% of the seed yield. Increasing density decreased the percentage contribution of the bottom portion of the plant to final yield. Fewer bottom pods would be beneficial in reducing harvest losses with small, early-maturing soybeans.
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