|St Martin, S - OARDC/OSU|
|Fioritto, R - OARDC/OSU|
|Schmitthenner, A - OARDC/OSU|
|Dorrance, A - OARDC/OSU|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 21, 2000
Publication Date: N/A
Interpretive Summary: When soybean yields ranged from 15 bushels/acre to 40 bushels/acre, a single soybean variety could be developed that would produce the highest yield across this range of yield levels. However as soybean yields have increased to 50, 60 and 70 bushels/acre or more, it has become increasingly more difficult to produce a single variety that is highest in yield over this entire yield range. Such broadly adapted varieties tend to be too tall (produce too much vegetative growth) in high yield environments and tend to fall over (lodge). This lodging interferes with photosynthesis, reducing the yield potential, and can cause harvesting problems and seed loss. In the lower yielding environments, broadly adapted varieties which have been selected for shorter plant height to prevent lodging, tend to be too short for best yields. Thus to over come this problem, determinate semidwarf varieties have been developed with specific adaptation to high yield environments. These varieties are much shorter than the traditional indeterminate varieties that have been selected for broad adaptation and are recommended for planting only on soils with a history of high yields (50 bushels/acre or higher). In these environments the semidwarf varieties can significantly out yield the taller indeterminate varieties which frequently become severely lodged. Strong is a new determinate semidwarf soybean variety adapted to the southern portion of the corn belt states, released in 1999, which has shown exceptional yield potential in high yield environments.
Technical Abstract: Strong is a maturity group IV determinate semidwarf soybean variety released in 1999. It is a F4-derived line, originally designated as HC94-422, from the cross, Sprite 87 x HC85-6557. HC85-6557 is a determinate semidwarf line from the cross, HC78-350 x HC78-676, HC78-350 is a semidwarf line from the cross, L72U-2567 x Essex. L72U-2567 is an F2-derived line from the cross, Williams x Ransom. HC78-676 is a semidwarf line from the cross, L70T-543G x L74D-519. L70T-543G is an indeterminate line from the cross, L15 x Amsoy 71. L15 is a BC5-derived near isogenic line of Wayne containing the Rpsl-a allele from Clark 63. L74D-619 is a semidwarf line from the cross, Williams x Ransom. In high yield environments, Strong has averaged 10% higher yields than the maturity group III semidwarf variety, Charleston and in regional trials, 10% more than the group IV determinate semidwarf variety, Ripley, currently being grown. Like all semidwarf varieties, Strong is recommended only on soils with a history of high yields (>3300 kg/ha) and it should be solid-seeded in 17- to 20cm row spacing at a seeding rate of 750,000 seeds/ha of 90+% germination (675,000 viable seeds/a).