Coupling effects of soil moisture and BGA, a drought resistant agent, on cold resistance of Euonymus japonicus

Beijing Green Angle (BGA) is a new organic drought resistant agent. In order to investigate the effective coupling range of soil moisture and BGA dosage to improve the cold resistance of evergreen broadleaved shrubs that were planted in the cities of northern China, cold resistance was measured in field and pot experiments at China Agricultural University for Euonymus japonicus under various soil moisture and BGA dosage by an electric conductivity meter and field investigation.Resultsindicated that soil moisture, BGA dosage and their interaction all had significant impacts on frost tolerance of E. japonicus. When soil moisture ranged between 60% and 75% of field water capacity (FC), the frost tolerance of E. japonicus increased with an increase of BGA dosage, but decreased after BGA dosage reached the maximum value. The frost tolerance decreased linearly when soil moisture was less than 65% or higher than 75% of FC. When BGA was applied, frost tolerance of E. japonicus also increased with an increase of soil moisture. It decreased when soil moisture reached its maximum at 65%--75% of FC. Finally,we recommended an approximate coupling range of soil moisture and BGA dosage, which was suitable to cold resistance of E. japonicus.