Comparisons of MG IV and MG V Soybeans Planted in Twin and Single Rows at Varying Seeding Rates.

A study at Stoneville, MS compared twin-row vs. single-row plantings made in mid-April of MG VI and MG V soybeans seeded at 20, 30, 40, and 50 seeds m^-2 in 2008 and 2009.  Seed yields of the MG IV cultivar were greater than those of the MG V cultivar.  Row type and seeding rate had no impact on seed yield though final plant populations increased with increased seeding rates and twin-row plantings had higher final plant populations than single-row plantings.  The MG V cultivar produced more pods plant^-1 (59) than the MG IV (53) but row type or planting rate had no impact on this yield component.  The MG V cultivar had a greater LAI (8.8) than the MG IV (7.1) and the twin-row plantings had a greater LAI (8.2) than the single-row plantings (7.8).  Seed weight did not differ between cultivars, planting rates, or row type.  Twin-row plantings do not appear to have a yield advantage over conventional single rows and seeding rates above 20 seeds m^-2 are not advisable given current seed cost and the lack of yield increases with higher seeding rates.