Genotypic Variation of Sensitivities to Photoperiod and Temperature in Different Growth Stages in Soybean World Mini-Core Collections (GmWMC)

抄録

Short photoperiod and high temperature could be causal factors for the low productivity of soybean in tropical Asian countries. In order to find adaptable genotypes suited to tropical areas, we evaluated the variation in responses to photoperiod and temperature of soybean in the world mini-core collections (GmWMC). Seeds were sown in late May (long photoperiod) and early August (short photoperiod) from 2015 to 2017 in the field and in a growth chamber at Saga University, Japan. The dates of emergence, first flowering (R1), first pod appearance (R3), and the start of seed filling (R5) were recorded. The daily average temperatures and photoperiodic hours were collected from weather stations. The days from emergence to first flower open (DEF) were shortened by late sowing in all genotypes, whereas the accumulated temperatures during emergence to first flower open (ATEF) did not respond to sowing time in some early flowering genotypes, indicating that these genotypes may be insensitive to photoperiod. The accumulated temperature (AT) of R1–R3 (for pod formation) responded to the sowing time similarly to that for flowering. However, there were no such responses observed for AT of R3–R5 (for pod elongation). The growth chamber experiment showed a longer DEF at lower temperature; however, the ATEF and EATEF (effective ATEF) did not respond to the change in temperature. The results suggested that ATEF could represent photosensitivity better than DEF in natural conditions, and temperature might affect plant development quantitatively in soybean.