Abstract
Soybean isolines with different combinations of photoperiod sensitivity alleles were planted in a greenhouse at different times during the year resulting in natural variation in daily incident irradiance and duration. The time from planting to first flower were observed. Mathematical models, using additive and multiplicative modes, were developed to quantify the effect of photoperiod, temperature, photoperiod-temperature interactions, rate of photoperiod change, and daily solar irradiance on flowering time. Observed flowering times correlated with predicted times (R2 = 0.92, Standard Error of the Estimate (SSE) = 2.84 d, multiplicative mode; R2 = 0.91, SSE = 2.88 d, additive mode). The addition of a rate of photoperiod change function and an irradiance function to the temperature and photoperiod functions improved the accuracy of flowering time prediction. The addition of a modified photoperiod function, which allowed for photoperiod sensitivity at shorter photoperiods, improved prediction of flowering time. Both increasing and decreasing rate of photoperiod change, as well as low levels of daily irradiance delayed flowering in soybean. The complete model, which included terms for the rate of photoperiod change, photoperiod, temperature and irradiance, predicted time to first flower in soybean across a range of environmental conditions with an SEE of 3.6 days when tested with independent data.
Highlights
Eight genes, which influence time from planting to first flower, have been identified in soybean [Glycine max (L.) Merr.] to date: E1 and E2 [1], E3 [2], E4 [3,4], E5 [5], E6 [6], E7 [7] and E8 [8]
Isolines with dominant E alleles at two or three loci flowered earlier under low temperature (18 C) and non-inductive photoperiods compared to higher temperature (28 °C) with non-inductive photoperiods, but the time to flowering in both instances was still greater than the time to flower under inductive short photoperiods [14]
The soybean genotypes, maturity gene near-isogenic lines, used in this experiment shared one of two common genetic backgrounds “Harosoy” or “Clark” where combinations of early or later flowering alleles at various flowering loci were backcrossed into the recurrent parent (Table 1)
Summary
Eight genes, which influence time from planting to first flower, have been identified in soybean [Glycine max (L.) Merr.] to date: E1 and E2 [1], E3 [2], E4 [3,4], E5 [5], E6 [6], E7 [7] and E8 [8]. E3 [9] and E4 [10] have been identified as phytochrome A genes while E2 has been identified as a GIGANTEA homolog [11] and E1 as an inhibitor of FT [12] Alleles at these loci, in conjunction with photoperiod [13] and temperature [14], regulate the timing of flowering and maturity of soybean lines. Isolines with dominant E alleles at two or three loci flowered earlier under low temperature (18 C) and non-inductive photoperiods compared to higher temperature (28 °C) with non-inductive photoperiods, but the time to flowering in both instances was still greater than the time to flower under inductive short photoperiods [14] This result underscored the importance of the E genes in the adaptation of soybean lines to specific climates and highlighted the requirement for a thorough understanding of their function in controlling flowering
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
