Study On Water Use Efficiency Model And Growth Of Apricot Seedlings Based On Different Drip Irrigation Methods

Drip irrigation is an important means to improve the utilization rate of water resources and improve the irrigation efficiency of the forestry and fruit industry.In this study,the seedlings of ’Xiaobaixing’ in Aksu,Xinjiang were used as the material.Surface drip irrgation and root-zone drip irrigation were used to irrigate apricot seedlings at three irrigation rates(high water 750mL/time,medium water 500 mL/time,and low water 250mL/time)treatment,according to the differences in the morphological indicators and biomass of apricot seedlings under different drip irrigation,the differences in leaf microscopic morphological structure and chlorophyll content,as well as the changes in photosynthesis intensity and water use efficiency.A water use efficiency model based on stomatal conductance(Cond),intercellular CO2 concentration(Ci),leaf temperature(Ctleaf)and light intensity(PARo)was analyzed and constructed.By analyzing the effects of different drip irrigation methods on the growth of apricot seedlings and the model of water use efficiency,a theoretical basis was provided for formulating a reasonable irrigation system,improving the quality of seedlings and water use efficiency.The main test conclusions are as follows:(1)The growth of apricot seedlings can be significantly promoted when the amount of drip irrigation in the root zone is greater than 500mL.The growth of apricot seedlings was significantly better than other treatments when the surface drip irrigation was 750mL and the root zone drip irrigation was 500mL and 750mL.Drip irrigation in the root zone can significantly increase the plant height,biomass,number of branches per plant,stem diameter,main root length,number of lateral roots per plant,and root volume of apricot seedlings.The root-shoot ratio of apricot seedling roots increased significantly when the irrigation amount was 250 mL.At the same time,root-zone drip irrigation can also significantly promote leaf growth of apricot seedlings,and its leaf area and leaf circumference are larger than surface drip irrigation.The length and width of leaves,leaf shape index,leaf circumference,leaf area,etc.all tended to increase with the amount of irrigation.(2)The growth of leaves and the accumulation of chlorophyll content of apricot seedlings can be significantly promoted when the amount of drip irrigation in the root zone is greater than 500mL.The spongy tissue of leaves of apricot seedlings at the root zone drip irrigation amount of 500mL and 750mL were thicker,and the palisade tissue was thinner.The thickness of upper and lower epidermis,palisade tissue and spongy tissue of leaves were significantly lower when the surface drip irrigation was 250mL.The palisade tissue of leaves was significantly thicker and the thickness of spongy tissue was significantly lower when the drip irrigation in the root zone was 250mL.The leaf pigment content of the plants with the irrigation amount of root-zone drip irrigation greater than 500mL was significantly higher than that of the surface drip irrigation,and the chlorophyll content was significantly higher when the root zone drip irrigation irrgation amount was 750mL.(3)The photosynthesis and water use efficiency of apricot seedlings can be significantly improved when the water volume of drip irrigation in the root zone is more than 500mL.Root zone drip irrigation is beneficial to maintain higher soil water content and electrical conductivity when the irrgation volume is 250～750mL.The photosynthesis and water use efficiency of plants under drip irrigation in the root zone were significantly higher than those under drip irrigation at the surface,but they decreased when the irrigation amount of drip irrigation in the root zone was 750mL.The water use efficiency model constructed by using photosynthesis-related indicators has a good fitting effect,and the water use efficiency model of root-zone drip irrigation(R2=0.9924)is better than that of surface drip irrigation(R2=0.9890).(4)Correlation analysis and principal component analysis showed that plant height was significantly positively correlated with root volume,stem diameter,leaf length and leaf shape index,and plant height was extremely significantly positively correlated with root volume.Stomatal conductance(Cond)and transpiration rate(Trmmol)were significantly positively correlated with the photosynthetic rate(Photo),and significantly negatively correlated with water utilization.The cumulative contribution rate of the morphological indexes of the first three principal components of the principal component analysis was 87.9579%,and the physiological indexes were 89.2074%.Root-zone drip irrigation was more conducive to the growth of apricot seedlings.The morphological indicators were greatly affected by plant height,stem diameter and leaf circumference,and the physiological indicators were greatly affected by upper epidermis thickness,total biomass,and stomatal conductance(Cond).