Research On Occurrence Regularity Of Walnut Bleeding And Its Relationship With Main Ecological Factors

In order to study the law of walnut bleeding,it provides a basis for scientific pruning and grafting of walnut.In the study from 2017 to 2019,the early-season walnut ‘Xiangling' and ‘Liaohe No.4' were used as materials to study the occurrence of walnut bleeding flow by the combination of outdoor observation and indoor measurement.Its relationship with ecological factors,using correlation analysis and regression analysis to screen out the main ecological factors affecting the law of walnut bleeding.The following conclusions are drawn:(1)The variation rules of bleeding in winter and spring of the two walnut varieties were basically the same,and the starting time of bleeding was basically the same.The beginning of winter bleeding in walnuts is in late November,no bleeding in late February;and the bleeding flow is large in late November,mid-December,and early February.The spring bleeding begins in early March,and the bleeding flow is the largest in late March.The stop time is about late April.There were significant differences in walnut bleeding between different varieties and seasons(P<0.05).(2)The starting time of walnut bleeding flow starts from 8:00 to 9:30,and the stop time is from 15:00 to 16:30;The daily variation of bleeding in the two varieties showed a trend of “low-high-low”;the difference of walnut daily bleeding in different varieties was significant(P<0.05).(3)The bleeding flow of walnut in winter was large when the average daily temperature was close to 0? and the ground temperature of 20 cm was close to 3?.The bleeding flow rate of walnuts increases with the daily average temperature,the temperature of 20 cm and the accumulated temperature of the day.The temperature,20 cm ground temperature,and accumulated temperature rose to 13.75?,14.3?,and 147?,respectively,and the bleeding gradually decreased until it stopped.The winter and spring bleeding flows of walnuts increased with the increase of sunshine hours and increased with decreasing relative humidity of air.(4)The bleeding flow is greatly affected by the weather.The weather is the most common on sunny days,followed by cloudy weather.There is basically no bleeding on cloudy days,and there is no bleeding on rainy days and snowy days.(5)After regression analysis,the winter bleeding flow was significantly positively correlated with sunshine hours,and negatively correlated with daily average temperature;sunshine hours and daily average temperature were the main ecological factors affecting winter walnut bleeding.There was a significant negative correlation between spring bleeding and relative humidity of air;air relative humidity was the main ecological factor affecting spring bleeding.(6)The daily variation of walnut bleeding was affected by the relative humidity of the air and the soil temperature of 20 cm,which was significantly negatively correlated with the ground temperature of 20 cm,and was significantly positively correlated with the relative humidity of the air.(7)The appropriate pruning period can be selected from mid-November or mid-February;the spring grafting period is selected from mid-April to early May.