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Photoperiod

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Photoperiod And Planting Date Effects On The Spatial Distribution Of Branch Development In Soybean, John Settimi, James Board Dec 1987

Photoperiod And Planting Date Effects On The Spatial Distribution Of Branch Development In Soybean, John Settimi, James Board

John R. Settimi

Reduced branch development in late-planted soybean [Glycine max (L.) Merr.] is a cause of yield reductions in the southeastern USA. To determine the effects of photoperiod and planting date on the spatial distribution of branches, photoperiod simulations of an optimal (24 May) and a nonoptimal late planting date (24 June) at Baton Rouge, LA (30°N Lat), were imposed on ‘Centennial’ soybean in growth chambers. In a field study, ‘Lee 74’ was planted at optimal (mid-May) and nonoptimal (early July) planting dates in 1984 and 1985 at Baton Rouge, LA, on an Olivier silt loam (fine-silty, mixed thermic Aquic Fragiudalf) soil. …


Photoperiod Requirements For Flowering And Flower Production In Soybean, John Settimi, James Board Dec 1985

Photoperiod Requirements For Flowering And Flower Production In Soybean, John Settimi, James Board

John R. Settimi

Photoperiod has been recognized as playing a major role in soybean [Glycine max (L.) Merr.] growth and development. The objective of these studies was to determine the number of short days (13.5h) representative of early spring daylengths in the southeastern United States necessary to cause anthesis and adequate flower production in soybean. Growth chamber studies were conducted at the Phytotron at North Carolina State University, during the first 26 wk of 1985. The soybean cultivar Tracy-M and the delayed flowering genotype D77-12480 were subjected to treatments in which they were transferred either from short-day (13.5-h) to long-day (16-h) or long-day …


Photoperiod Effect Before And After Flowering On Branch Development In Determinate Soybean, John Settimi, James Board Dec 1985

Photoperiod Effect Before And After Flowering On Branch Development In Determinate Soybean, John Settimi, James Board

John R. Settimi

Previous research indicated that restricted branch development was a factor associated with soybean [Glycine max (L.) Merr.] seed yield reductions at late planting dates in the southeastern United States. The present studies were conducted to outline the progress of branch development at different planting dates and to determine the role of photoperiod in branch restriction at late planting dates. In field studies, eight cultivars were planted at early April (nonoptimal), mid-May (optimal), and mid-June (nonoptimal) planting dates in 1982 and 1983 at Baton Rouge, LA (30°N Lat), on an Olivier silt loam (fine-silty, mixed, thermic Aquic Fraguidalf) soil. Plants were …