地布覆盖不同滴灌量条件下苹果树干液流变化特征研究

Study on the changes in liquid flow characteristics of apple tree under different drip irrigation rates and ground cover conditions

[目的]本研究旨在探究地布覆盖条件下滴灌苹果树的蒸腾耗散规律,为合理制定适宜的果园灌溉制度提供理论方法。[方法]采用插针式植物热扩散液流计于2022年5月-10月,连续监测不同水分处理下滴灌苹果树新梢生长期至成熟期的液流速率变化特征,并结合气象数据分析树干液流速率与气象因子的相关关系,最后利用XGBoost模型建立液流速率与气象因子的关系模型。[结果]苹果树干液流速率在生育期内均呈单峰型曲线,具有明显的昼高夜低日变化特征。生育期的对比表明,新梢生长期苹果树干的单日速率峰值、单日平均液流速率、生育期平均速率及生育期最大值均处于生育期最高水平。不同灌溉处理的液流变化对比显示,低水处理时苹果树干液流变化强度明显减弱,其单日速率峰值、单日平均液流速率、生育期平均速率及生育期最大值较高水处理降低了37.08%~65.27%。全生育期气象参数对树干液流速率的影响强度大小为:太阳辐射>饱和水汽压差>大气温度>相对湿度>风速,其中太阳辐射对果树液流变化的正效应最显著。在此基础上,利用XGBoost算法建立了基于气象参数的苹果树液流速率预测模型,模型的决策系数为0.815。[结论]苹果树的生育期差异、灌溉处理、气象变化对树干液流变化均具有显著影响,其中新梢生长期果树生长旺盛,且受高辐射天气的影响,使得果园的蒸腾耗散强度增加。

[Objective]The purpose of this study was to investigate the transpiration dissipation patterns of apple trees under ground cover and drip irrigation conditions,and to provide a theoretical method for the rational development of appropriate or-chard irrigation systems.[Method]From May to October 2022,a needle-type plant thermal diffusion liquid flow meter was used to continuously monitor the liquid flow rate characteristics of drip-irrigated apple trees under different water treatments,from new shoot growth to mature stage.The study also analyzed the correlation between trunk liquid flow rates and meteoro-logical factors.Finally,an XGBoost model was used to establish a relationship between liquid flow rates and meteorological fac-tors.[Result]The results showed that the liquid flow rate of apple trees exhibited a unimodal curve throughout the growing sea-son,showing distinct diurnal variation characteristics,with higher rates during the day and lower rates at night.Comparing dif-ferent growth periods,it was found that during the new shoot growth period,the single-day rate peak,single-day average liquid flow rate,average rate during the growth period,and maximum value during the growth period were all at their highest levels.A comparison of liquid flow changes under different irrigation treatments showed that the intensity of liquid flow changes in low water treatments was significantly reduced,with the single day rate peak,single-day average liquid flow rate,average rate dur-ing the growth period,and maximum value during the growth season decreasing by 37.08%~65.27%compared to high water treatments.The impacts of meteorological parameters on trunk liquid flow rates during the entire growth period was ranked as follows:solar radiation>saturation vapor pressure deficit>air temperature>relative humidity>wind speed,with solar radia-tion having the most significant positive effects on fruit tree liquid flow changes.Based on this information,an XGBoost model was used to establish a liquid flow rate prediction model for apple trees based on meteorological parameters,with a model coeffi-cient of determination of 0.815.[Conclusion]Different growth stages of apple trees,irrigation treatments,and meteorological changes all have a significant impact on trunk liquid flow changes.In particular,the vigorous growth of fruit trees during the new shoot growth period,coupled with the influence of high radiation weather,increased the transpiration dissipation intensity in the orchard.