Study On Water Consumption Characteristics Of Jujube Trees Under Pruning And Limited Growth

In this study,the size of the tree body,the number and length of branches were controlled through field experiments in jujube pruning,the soil moisture content and the growth index of jujube trees were measured,the individual biomass,water consumption and water use efficiency of jujube trees were measured,and the relationship between the biomass and water consumption characteristics of jujube trees was analyzed,trying to explore the water consumption characteristics of jujube forests under the condition of strictly limiting the growth specification of jujube trees.After three years of continuous monitoring(2015-2017),the following conclusions are obtained:1.In the early stage of flowering and fruiting,the growth rate of primary branch length and jujube hanging length is extremely high,which is the rapid growth stage of both,and then the growth slows down,while the secondary branch shows the trend of uniform growth in the whole growth stage.The aboveground biomass of jujube trees in each district showed a unimodal curve growth,reaching the maximum at fruit maturity.The aboveground biomass of jujube trees in the five districts showed basically the same change trend.There was no significant difference in the aboveground total biomass of jujube trees in each district at the end of the observation period,indicating that the individual biomass of jujube trees can be limited to a certain range by controlling the tree size.2.Soil water deficit caused by water consumption by vegetation is the main reason for the formation of dry soil layer.In-depth study of water consumption characteristics of jujube forest is the key to maintain the stability of jujube forest ecosystem.After study,we found that there was no significant difference between aboveground biomass and soil water content in water-consuming layer in each treatment,which proved that pruning to restrict jujube growth had obvious effect on restricting jujube water consumption.Although the water consumption of jujube trees will increase slightly and the biomass of jujube trees will also increase slightly in years with sufficient soil moisture or heavy rainfall,pruning that restricts the growth of jujube trees can still be used as a measure to prevent excessive consumption of soil moisture.3.With the growth of forest age,the water consumption depth of pruned jujube forest is less than that of natural jujube forest.According to the pruning specification adopted in the experiment,the water consumption depth of 5-year-old jujube trees is about 3.2m,which is 1.2m less than that of 5-year-old jujube trees in conventional dwarf densely planted mountain areas.This depth can be recovered through year with abundance of water and can supplement the soil moisture in the lower layer.Therefore,the depth of 3m soil drying can be regarded as temporary dry layer,that is,the allowable dry layer depth.The average water consumption in the three years of each treatment in the observation period in the test area is 520.78 mm,which is basically the same as the local average rainfall of 548.40 mm,and the supplement and consumption of soil water in the forest land are basically the same.This shows that controlling the growth of jujube trees can regulate the water consumption in the jujube forest land.The pruning intensity adopted in the test conforms to the local rainfall conditions and can be used as a reference for controlling water-saving pruning.In dry years with water deficit,we can also increase irrigation,cover and preserve soil moisture and other measures on the basis of water-saving pruning to limit ineffective water consumption in jujube orchards as far as possible,which is of great significance to realize sustainable development of jujube forests and prevent and control soil desiccation in jujube forests.4.Jujube trees grow normally depending on natural rainfall in a limited growth space.The experiment did not reduce the yield of jujube trees.The yield of jujube forest in different years is affected by rainfall.The yield is higher in years with sufficient water and lower in years with insufficient water.Proper pruning can restrict vegetative growth and promote reproductive growth,thus improving the water use efficiency of jujube trees.Compared with the conventional dwarf densely planted mountain jujube trees,the biological water use efficiency and yield water use efficiency of the test jujube trees are improved,and the water use efficiency is high,which means that the jujube trees use water more economically.This shows that water-saving pruning has certain application value in production,and the pruning specifications adopted in the test can be used as a reference for local production management.