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
