Response of Soybean Cultivars to Planting Patterns1

Abstract

AbstractSince soybean [Glycine max (L) Merr.] acreage continues to increase in the higher latitudes of the world the objective was to obtain agronomic information on the effect of inter and intra‐row spacings on several of the most widely grown, early cultivars in America. Ten soybean cultivars differing in maturity (Group 0 through II) and growth characteristies were grown in two row spacings (27‐cm and 76‐cm) and varying populations (132,000 to 741,000 plants/ha) for 3 years in field trials on Typic Arguidolls fine silty; mixed mesic soil near Madison, Wis.Planting soybeans in 27‐cm rows vs. more conventional 76‐cm rows showed an average seed yield increase of 21% over all years, populations, and cultivars. All cultivars produced higher seed yields in narrow row spacings. The three early cultivars (Group O Maturity) generally exhibited a greater yield response (+27%) to narrow row spacings than did cultivars in Maturity Groups I and II (+19%). However, the later maturing cultivars generally produced the highest yields over all row spacings, plant populations and years. Varying the intra‐row plant spacing did not significantly affect seed yields. Increasing plant populations decreased the number of branches per plant and increased lodging, seed weight, and LAI. While the LAI increased as plant population increased in both the narrow and wide rows, no correlation existed with grain yield. Increasing the plant population in each row spacing increased the height of the lower pod by a range of 40 to 50%.The availability of new varieties with improved lodging resistance and herbicides with greater selectivity may lead to an accelerated acceptance of narrow row soybean production systems to capitalize on the increased yield potential in the northern growing regions.