Abstract:

In order to clarify the frost disaster index of soybean in grain filling stage, this study took the local main cultivar ‘Mengdou 13’ as the test object, and used the frost box artificial simulation frost test and field frost investigation to verify it in the Dahewan soybean test base of Zhalantun. By analyzing the frost damage rates of soybean leaves, pods, and stems under different low-temperature conditions, as well as the relationship between temperature intensity, duration, and frost damage rate, a frost damage index based on accumulated harmful temperature (AHT) was established using regression analysis and subsequently validated. The results showed that: (1) during the grain-filling stage, leaves were the most frost-sensitive, followed by pods, while stems exhibited relatively higher frost tolerance. (2) The critical temperature for frost damage in soybeans was 1℃. Below this threshold, both frost injury rate and mortality rate increased with the decrease of temperature or prolonged exposure. When temperatures reached -1℃, the rates of frost injury and mortality increased significantly. (3) Frost injury and mortality rates were significantly positively correlated with AHT. The AHT thresholds for mild, moderate, and severe frost damage were 0℃·h≤K≤3.9℃·h, 3.9℃·h<K≤7.9℃·h, and K>7.9℃·h. This study determined the critical frost temperature and accumulated harmful temperature indices for soybean at the grain-filling stage under varying degrees of frost damage, providing technical support for the monitoring, early warning, and assessment of soybean frost damage.

Key words: soybean, grain-filling stage, frost, accumulated harmful temperature (AHT), indicator construction, frost box simulation experiment