The key point to extend soybean growing area to the cool, long day length, and short-growing season regions of the high latitude is breeding of day-neutral and cool-tolerable extremely early cultivars. Several countries have already got a distinct achievement in this respect. For example, extremely early soybean cultivars of Maturity Group 00 even 000 have been developed in countries of North America and North Europe.
Wang, Chin-ling and Kao, Fun-lang
"Research notes: Transgressive inheritance of early maturity for breeding of
extremely early soybean cultivars,"
Soybean Genetics Newsletter: Vol. 6
, Article 14.
Available at: http://lib.dr.iastate.edu/soybeangenetics/vol6/iss1/14