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Martinsville, Ohio | "Temperature and Photoperiod
The duration of the soybean life cycle (from seed to seed) and duration of the individual phases of development within the life cycle are dependent on photoperiod and temperature.
Photoperiod
Plants are defined as either short-day or long-day plants based on the response of flower initation to duration of the photoperiod (actually, it is duration of the number of hours during the nightthat determines the photoperiod reponse). Soybeans are short-day plants and, therefore, they flower earlier under short daylengths (i.e., during the month of June daylength in Southern Ontario is about 16 hours, which is a long photoperiod, whereas it is about 12 hours at locations near the equator; in contrast, photoperiod is much shorter during the months of August and September). There is evidence to suggest that developmental stages other than flowering are also photoperiod sensitive in soybean. Indeed, the seed filling period and, therefore, the time to harvest maturity is also photoperiod sensitive. Soybean cultivars are classified according to their response to photoperiod. There are 10 maturity classes: in Ontario, the earliest maturing cultivars that are adapted to Northern Ontario are designated 000, and later maturing cultivars that are adated to more southern locations are designated either 00, 0, I, or II; maturity class increases when moving further south, to VIII in he Southern US. "
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Couple of ?'s on alfalfa and soybeans.
