Photoperiod and temperature influence the growth, development and area of adaptation of soybean cultivars (Shanmugasundaram, 1981). Germplasm collected from the U.S. Maturity Groups 00 to X were screened for photoperiodic response and were classified into 10 different photoperiod sensitivity score groups, based on flowering in 10 and 16 hr photoperiods (Shanmugasundaram, 1981). By utilizing 0 sensitivity score types as one parent, high yielding selections with different levels of photoperiod sensitivity have been developed.
Shanmugasundaram, S. and Yen, Chung-Ruey
"Research Notes : Relationship between photoperiod, temperature, solar radiation and grain yield in soybean,"
Soybean Genetics Newsletter: Vol. 9
, Article 31.
Available at: http://lib.dr.iastate.edu/soybeangenetics/vol9/iss1/31