Effect Of Regulated Deficit Irrigation On The Microchange Of Yellow Crownpear Stem Diameter

Through deficit irrigation,Huangguan pear trees ware used as experimentalmaterial to measure the shoot growth,fruit dynamic changes,fruit quality,soil water potential,stem diameter Micro-changes and meteorological factors of Huangguan pear trees under drip irrigation.The following conclusions:?1?Shortage treatment at shoot growth stage and young fruit development stage significantly decreased shoot growth and increased with the deepening of water deficit.Mild water deficit treatment had no effect on fruit quality and yield in the early stage,and had no significant effect on fruit quality and yield in the ripening stage,while continuous severe water deficit treatment could affect fruit growth and quality.?2?The diurnal variation of stem diameter of pear tree was 24 h periodic,the diurnal variation curve is"U"type,the maximum of stem diameter?MXSD?appears around 8:00,the minimum of stem diameter?MNSD?appears around 17:00 p.m.The diurnal variation trend of stem diameter is the same under different weather conditions,the maximum of stem diameter?MXSD?and the minimum of stem diameter?MXSD?day.The occurrence time of MNSD was basically the same,but the daily shrinkage of stem diameter?MDS?and daily increment?DI?were significantly different.?3?The soil water potential at the depth of 20 cm,40 cm and 60 cm decreased rapidly within 12 days after irrigation and slowly after 12 days.On the 21st day after irrigation,the soil water potential was about-20.5 kPa.At the same time,therelationship between soil water potential and time t?day?in different depths was found to be:Depth of 20cm:Y=-1.157t-1.884?R²=0.964?Depth of 40cm:Y=-6.618t3-0.442t2-0.012t-20.722?R²=0.997?Depth of 60cm:Y=-0.206t+0.214.?R²=0.973?With the decrease of soil water potential,when the soil water potential exceeds a certain critical value,the MNSD of pear tree rises first and then falls,the MDS first drops and then rises.The daily recovery time of stem diameter?RT?continues to increase.Soil water potential and maximum daily shrinkage:Y=0.293x2+10.674x+466.722?x is soil water potential?Soil water potential and daily increase of stem:Y=-0.036x2+0.102x+20.873?x is soil water potential?According to the fitting curve,when the soil water potential drops to-22.7kPa,the stem diameter growth of pear trees stops,and negative growth begins to occur at the same time,-22.7kPa is the critical value of the stem diameter growth of pear trees.?4?Under the condition of adequate irrigation,MDS of pear trees are significantly affected by daily average temperature?T?,air relative humidity?RH?and light intensity?L?.MDS is positively correlated with T and L and negatively correlated with RH.Pear tree DI was mainly influenced by T,showing a positive correlation.Both MDS and DI are not affected by wind speed?u₂?.The linear regression analysis of MDS,DI and meteorological factors was carried out,and the linear regression equation was established:MDS=0.714 T-4.697+0.896+114.684 L?R²=0.887?DI=11.063 T-168.344?R²=0.696?Under the condition of regulated deficit irrigation,MDS of pear tree was significantly affected by T,RH and L,all of which were positively correlated.Pear tree DI was significantly correlated with T and L,both of which were negatively correlated.Both MDS and DI are not affected by wind speed?u2?.The linear regression analysis of MDS,DI and meteorological factors was carried out,and the linear regression equation was established:MDS=3.616T+2.129RH+2.129L-176.569?R²=0.940?DI=-3.213T-0.144L+154.511?R²=0.769?...