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ARS Home » Research » Publications at this Location » Publication #61857
Title: SEPARATING TEMPERATURE AND PHOTOPERIOD EFFECTS ON GROWING DEGREE DAYS FROM EMERGENCE (VE) TO FLORAL BUD INITIATION (R0) AND FLOWERING (R1) IN SOYBEAN.

Author
item ZHANG, L - UNIV OF ILLINOIS, URBANA
item WANG, R - UNIV OF ILLINOIS, URBANA
item Hesketh, John

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 9/1/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The date-of-planting data set report last year was reanalyzed to separate out of temperature effect from photoperiod effects on Growing Degree Days (GDD) to floral bud initiation and flowering among genotypes adapted to Urbana IL. A second order equation was fitted to GDD between VE, RO and R1 events for early genotypes (Acme-MG00, L71-920-MGI and L65-778-MGI+) plotted against temperature, accounting for 70 to 85% of the variation. A GDD value was then estimated for the same growth period of other genotypes varying in MG II to VI, based upon the average temperature between events and the GDD temperature function for the very early maturing genotypes. Such "temperature adjusted" GDD values were them subtracted from measured ones of later-maturing genotypes, and the remainders were plotted vs. photoperiod, resulting in much better fits of equations to the adjusted VE-RO GDD data vs. photoperiod. The photoperiod used was either the average for the growth period or that at RO. The photoperiod at RO resulted in better-shaped adjusted GDD response curves for MG II-IV (as well as for MG V-VIII). Changing the base temperature from 10 to 7 deg did not help much in improving equation fits to data. We are still searching for how to calculate photoperiod to give the best fit of equations to data and the most biologically meaningful shape of the response curve.