Long Juvenile Soybean Flowering Responses under Very Short Photoperiods

Abstract

Long juvenile (LJ) soybean [Glycine max (L.) Merr.] lines exhibit delayed flowering under short photoperiods. Two loci, J and E6, have been reported to control this response. The objectives of this work were to compare phenology of E6E6 and e6e6 isolines across a range of photoperiods, to determine the genetic control of the LJ trait during the introgression of e6 into an early maturity background, and to compare e6e6 and jj lines in short photoperiods. Flowering time of ‘Paraná’ (E6E6) and its LJ isoline ‘Paranagoiana’ (e6e6) was observed in photoperiods of 3 to 16 h. Both lines flowered late (about 100 d) in a 16 h photoperiod. Paraná flowered in less than 30 d in 6, 8, 10, and 12 h photoperiods. Paranagoiana responded to decreases in photoperiod from 12 to 4 h with earlier flowering, although always flowered a minimum of 5 d later than Paraná. The LJ trait in Paranagoiana was introgressed into OT94‐47 with selection for late flowering under 12 h photoperiods. From the initial cross to the third backcross, F2 populations exhibited a 15:1 early:late flowering ratio in 12 h photoperiods. A similar 15:1 ratio was observed in a cross between OT94‐47 and LJ PI 159925. In comparisons, under 3 to 12 h photoperiods, Paranagoiana and PI 159925 flowered similarly and later than Paraná. It appears that the LJ lines may have a 5 d juvenile period but flowering delays greater than 5 d are likely due to photoperiod responses to very short photoperiods (≥5 h).

The effects and interaction of soybean maturity gene alleles controlling flowering time, maturity, and adaptation in tropical environments

“…Numerous studies suggested that in certain backgrounds the long juvenile trait was under the control of a single gene [13,18]. However, delayed flowering was shown in a 1:15 segregation ratio in other studies [36,38] suggesting that another gene was able to influence the long juvenile phenotype.…”

QTL mapping for flowering time in different latitude in soybean

“…A similar 15:1 ratio was observed in offspring of a cross between CJ line OT94-47 and the LJ line PI 159925. These results suggest that the LJ trait is conditioned by at least two recessive alleles in PI 159925 and Paranagoiana (Cober 2011). Further studies of LJ parents have shown that recessive alleles at two or three loci control the long-juvenile trait (Carpentieri-Pípolo et al 2000, 2002.…”

Inheritance of late flowering in natural variants of soybean cultivars under short-day conditions

“…In contrast, plant populations sown in experiment III experienced early flowering, due to the increased night temperatures, which significantly affect the process of flower induction in the dark. The monthly mean air temperature from emergence to (Cober, 2011). Liu et al (2011) reported that in a tropical location, such as Thailand, planting starts in November because flowering time is affected by warmer temperature rather than by the photoperiod; therefore, the high temperature during the night has a more significant effect on the induction of flowering.…”

“…Therefore, an understanding of the genetic control of this trait and the ability to perform efficient selection strategies are essential to produce new cultivars that are adapted to a larger variety of environments (Kong et al, 2010;Cober, 2011).…”