Delayed Emergence of Soybeans Due to Drought and Soil Crust Does Not Extend the Period from Emergence to Flowering

We evaluated the effects of delayed emergence of soybean caused by drought and soil crust on soybean growth (development from emergence to flowering and yield per plant). We carried out a field experiment (soil crust simulated with wooden boards) and a pot experiment (with actual soil crust). Soybean cultivars Toyomusume, Tsurumusume, and Yukihomare were sown on a conventional sowing date in control plots, dry soil plots, and soil crust plots and 13 or 14 days later in a late-sown plot. Delayed emergence due to drought shortened the period from emergence to flowering, or had the same effect on the flowering date as late sowing. Delayed emergence by up to 11 days due to soil crust resulted in earlier flowering compared to plants delayed by late sowing. These results mean that in cases where late flowering is expected because of delayed emergence caused by drought or soil crust, resowing would not restore the earlier flowering date.