[Differences in light and heat utilization efficiency and yield of soybean in two ecological zones and their response...

The field experiment was conducted at two farms at Jiusan in Heihe (the fourth accumulated temperature zone) and at Lindian County of Daqing (the second accumulated temperature zone), both sites located in Heilongjiang Province, China. With soybean Kenfeng 41 as the test material, uniconazole (S₃₃₀₇, 50 mg·L^-1) and 2-N, N- diethylamino ethyl caproate (DTA-6, 50 mg·L^-1) were sprayed on leaves in the early flowering period of soybean. Through grey correlation analysis, the main factors affecting soybean yield were examined, and the differences of the light and heat utilization efficiency and soybean yield in two ecological conditions were compared. The regulation effects of chemical control technology on the light and heat utilization efficiency of soybean were explored. The results showed that the total surface radiation and ≥10 ℃ effective accumulated temperature were the main factors affecting soybean yield in both areas compared with rainfall and sunshine hours. The light and heat utilization efficiency from sowing to flowering period was significantly positively correlated with dry matter accumulation, and that from flowering to podding period was significantly positively correlated with dry matter accumulation per plant. There was a significant positive correlation between yield and dry matter accumulation, grain number per plant, grain mass per plant and 100-grain mass at seedling stage to podding stage. S₃₃₀₇ and DTA-6 could significantly improve light and heat utilization efficiency and soybean yield in both areas. S₃₃₀₇ showed the better regulation function to impact the light and heat utilization efficiency and yield than DTA-6 in both sites. In the two ecological areas of Jiusan and Lindian, spraying S₃₃₀₇ increased light utilization efficiency by 13.6% and 17.1%, and increased heat utilization efficiency by 14.1% and 17.2%, respectively. The yield by spraying S₃₃₀₇ was increased by 14.1% and 17.3% separately in Jiusan and Lindian. Therefore, it is the effective way to enhance resources utilization and achieve high-yield by using the reasonable chemical control technology.