Analysis And Evaluations Of Integrated Prevent Techniques On Apple Spring Frost-Freezing

Under the general background of global climate change, the warming trend of the main apple production areas in China during winter and early spring has been being more and more obvious. Besides, with the increasing of warmer winter and spring, and the enlarging of interannual variation range of air temperature, the fruit phenophase was ahead of time and the fruit cold resistance was declined. Sharp cooling processes would easily appear when the temperature raised quickly in the spring, so the injury risks of fruit trees suffered from the late frost freezing has been being increased, therefore, there have considerable realistic significances for the fruits security production through researching the frost freezing injury, monitoring and prediction, and integrated prevention techniques. In order to obtain a theoretical basis for the prevent of apple spring frost, the five-year old Red Fuji apple/M26/Malus Robusta were used as experiment materials, and the four representative techniques which were flood irrigation in early spring, water spray in night, the applied fog of smoker sprayer and spray the antifreezes were chose to prevent the spring frost. The temperature and humidity of air and soil were monitored after irrigation and spraying water(fog). What’s more, several physiological indices of cold resistance of apple leaves were measured after spraying the antifreezes. At last, the simulative effectiveness of four techniques was researched, their advantages and disadvantages were evaluated, and some ideal antifreeze was selected out. The results showed that:(1) the effects of irrigation in early spring on air temperature and humidity were varied with the change of the heights above the ground. Daily average temperature, maximum air temperature, heating rate in daytime, daily-range of temperature at 0.5 meters above the ground with flood irrigation were lower by 2.62℃, 4.93℃, 29.59% and 5.14℃ respectively compared to the controls, all of the differences were reached the siginificance level. Besides, the effects of irrigation on the air temperature of 0.5m surface layer manifest as cooling effects, Its average temperature and minimum temperature of air in night were decreased 2.31℃ and 0.48℃ respectively compared to the controls. the daily temperature range and average temperature were decreased 0.43℃ and 0.28℃ respectively compared to the controls; the average temperature and minimum temperature of air in night were decreased 0.84℃ and 1.96℃, the differences were reached the siginificance level. On the contrary, the daily temperature range and average temperature of 3.0m height were increased about 0.15℃ and 0.73℃ after irrigation, but the average temperature and minimum temperature of air in night were increased 1.20℃ and 1.21℃, reached the siginificance level. The relative air humidity of the canopy was increased 4.96% by irrigation compared to the controls. The regulatory effects of irrigation on air temperature and humidity can sustain 2 or 3 days.(2) the day cooling effect of irrigation in spring on soil temperature was decreased with the deepening of the soil depth. The day cooling effect on the 20 cm depth soil was most remarkable after irrigation and the daily average soil temperature was decreased 1.03℃ compared to the controls, and the differences were reached the siginificance level. The daily-range of temperature and the maximum temperature of 0-60 cm depth soil was decreased by irrigation, the volatility of soil temperature was decreased, and varied more assuasive after irrigation. The daily maximum soil temperature at 20 cm depth, 40 cm depth and 60 cm depth were respectively decreased by 1.56℃, 0.27℃ and 0.38℃, and the average daily-range of soil temperature was decreased by 0.99℃, 0.68℃ and 0.09℃ respectively compared to the controls, and the soil temperature in night was raised by 0.83℃, 0.09℃ and 0.27℃, and all of the differences were reached the siginificance level compared to the controls. The 0-60 cm depth soil humidity was increased dramatically after irrigation, the soil humidity of 20 cm depth, 40 cm depth and 60 cm depth was decreased by 38.65%, 21.61% and 8.52% respectively compared to the controls. The regulating effects of irrigation on temperature and humidity of soil can sustain one week.(3) the effect of water spray in night on air temperature was changed with the variation of spraying times. The continuous spraying from 00:00 to 06:00 had the best effects among all the treatments. The minimum air temperature and average air temperature of the orchard were increased, and the change range of air temperature became mitigated during the 00:00-06:00 water spray. The average canopy air temperature in night of 0.5 m, 1.5 m and 3.0 m heights above the ground were increased by 1.79℃, 2.12℃ and 2.53℃ compared to the controls respectively, the minimum air temperature in night was increased by 1.77℃、2.58℃、2.55℃, and the temperature drop range in night was decreased by 0.14%、4.93%、4.41%. The orchard air temperature in daytime was influenced dramatically by water spray. The daily average temperature was lowed 0.99℃、1.26℃、0.53℃compared to the controls respectively, the average daily range of air temperature was lowed 3.18℃、4.11℃、3.09℃, the average daily growing rate was decreased by 12.58%, 16.77% and 13.23%, average daily maximum air temperature was decreased by 2.0℃, 2.3℃ and 1.3℃, and all of the differences were reached the siginificance level compared to the controls. The regulating effects on air temperature of water spray in 00:00-06:00 can sustain one 3 days.(4) the average air temperature and the minimum air temperature of different canopy heights before sunrise were increased dramatically by applied fog with the smoker sprayer, and the growing rate of orchard air temperature before sunrise was slowed down too. The average air temperature at 0.5m, 1.5m, 3.0m above the ground were increased 1.05℃, 1.02℃ and 1.75℃ compared to the controls respectively during the spraying time, the lowest temperature before sunrise increased by 1.93℃, 1.44℃ and 2.8℃ respectively, and the air temperature daily range were decreased by about 2.23℃, 0.9℃ and 3.33℃. What’s more, the temperature rising rate at 0.5m, 1.5m and 3.0m above the ground were lowered 6.27%, 2.87% and 11.53% after the water mist were stopped. The relative air humidity of the orchard was increased 8.31% averagely compared to the controls, and all of the differences were reached the siginificance level compared to the controls. The regulating effects of the water mist on air temperature and humidity of the orchard could sustain about 1 hour after the water mist was stopped.(5) through subordination function method, the comprehensive ranking of 5 kinds of antifreezes were: BR1500 times liquid, 0.5%CaCl2, 250mg/LSA, BR3000 times liquid, and BR750 times liquid. Among all the antifreezes, the BR1500 times liquid, 0.5% CaCl2 and 250mg/LSA had the perfect anti-freezing effects, all of them can applied and popularized in the spring frost prevention.