Study On Effect Of Soil PH Values And Shading On Physiological Characteristics Of Phalaris Arundinacea Var.picta

Phalaris arundinacea var.picta has beautiful leaves and beautiful shape,it has been widely used as a ornamental grass in gardens in recent years.However,with the rapid development of social economy,more and more urban green spaces are affected by human activities and construction,that leads to uneven distribution of soil pH and light conditions.In order to expand the application range of Phalaris arundinacea var.picta,in this paper,we use Phalaris arundinacea var.picta as the experimental material to study the effects of different soil pH and shading conditions on the physiological characteristics of Phalaris arundinacea var.picta.The research results provide a theoretical reference for the popularization and application of Phalaris arundinacea var.picta in gardens and the selection of ground cover materials under special conditions.The results are as follows:1.The daily change of net photosynthetic rate of Phalaris arundinacea var.picta was a single-peak curve,the peaks appeared at 10:00,the peak values were:10.9?mol·m^-2·s^-1?August?>10.6?mol·m^-2·s^-1?June?>7.37?mol·m^-2·s^-1?October?.Phalaris arundinacea var.picta had lower light compensation points and light saturation points,which were 48.11 to75.84?mol·m^-2·s^-1and 1067.15 to 1395.92?mol·m^-2·s^-1.It also had a high CO₂ compensation point and CO2 saturation point,which were 90.15 to 116.7?mol/mol and 1424.33 to1694.64?mol/mol.In August,the light compensation point and dark respiration rate of Phalaris arundinacea var.picta were less than in June and October,the light saturation point,maximum net photosynthetic rate,apparent quantum efficiency,and chlorophyll content were all higher than those in June and October.The CO2 compensation point of Phalaris arundinacea var.picta gradually increased with the seasons,the maximum appeared in October,which was116.70?mol^-2·s^-1.The carboxylation efficiency of Phalaris arundinacea var.picta were:0.0344?June?>0.0291?August?>0.0288?October?.2.Acid soil and alkaline soil had different effects on the morphology of Phalaris arundinacea var.picta.Tne pH4.0 treatment and pH5.0 treatment both increased the root-to-crown ratio and leaf area of Phalaris arundinacea var.picta,it also promoted plant height growth and childbirth,and the pH 5.0 treatment had the largest value.Alkaline soil inhibited the growth of Phalaris arundinacea var.picta.The relative water content of the leaf of Phalaris arundinacea var.picta treated with acid soil was lower than that of CK by 6.44%?pH 4.0?and 2.28%?pH 5.0?,respectively.The relative water content of leaves of Phalaris arundinacea var.picta treated with alkaline soil was 2.22%?pH 8.0?and 3.73%?pH 9.0?lower than CK,respectively.Acid stress was greater than alkali stress.The contents of the permeability regulators in the leaves of Phalaris arundinacea var.picta under acid stress were higher than those in CK,the value of the soil increased with the increase of soil acidity,the value increased with the increase of soil alkaline.The change in protective enzyme activity was the opposite,and its value decreased with increasing acidity and alkalinity of the soil.Soil pH 5.0 and pH 8.0 treatment change was smaller.The light response curve of soil treated with soil pH 5.0 was higher than other treatments,both the apparent quantum efficiency and the light saturation point were the maximum values,which were 0.024 and 1395.92?mol^-2·s^-1.The dark respiration rate of Phalaris arundinacea var.picta treated with soil pH 5.0 was less than other treatments,and the pigment content was higher than other treatments.The light saturation point,the light compensation point,the net photosynthetic rate,the apparent quantum efficiency,and the chlorophyll content of the leaves of the soil treated with soil pH 9.0 were the minimum values.3.Under shading conditions,the morphological and physiological indexes of Phalaris arundinacea var.picta had significantly changed.Moderate shade not only increased the leaf area,plant height and number of tillers,but also effectively reduced the rate of dead leaves.70%of the shade of Mild?30%?shading had less effect on relative water content and plasma membrane permeability of Phalaris arundinacea var.picta leaves grow best.Severe shading?90%?significantly reduced the root-to-crown ratio and number of tillers.which was a decrease of 49.37%and 28.57%compared with CK.Mild?30%?shading had little effect on the relative water content and permeability of the plasma membrane of Phalaris arundinacea var.picta.The water content of 70%shading was the highest at 15d,which was 92.66%.The plasma membrane permeability of leaves increased with the degree of shading.In the shaded environment,the changes of MDA and Pro in the leaves of Phalaris arundinacea var.picta were the same,the greater the degree of shading and the longer shading time,the higher its content.the changes in POD activity and SOD activity were opposite,90%of the shading treatment of Phalaris arundinacea var.picta had the lowest protective enzyme activity.Shading treatment reduced the maximum net photosynthetic rate and water use efficiency of Phalaris arundinacea var.picta leaves.The maximum net photosynthetic rate reached a minimum(1.9?mol·m^-2·s^-1)when shading was 90%.Moderate shading also increased the chlorophyll content of Phalaris arundinacea var.picta leaves.The content of chlorophyll a,chlorophyll b and carotenoids in leaves of 70%shading treated Phalaris arundinacea var.picta were highest,90%of shading had the lowest chlorophyll content and photosynthetic rate.In summary,the daily variation curve of the net photosynthetic rate of Phalaris arundinacea var.picta was a unimodal type,and the peak appeared at 10:00.In August,Phalaris arundinacea var.Picta had the strongest photosynthesis ability.It was not only had high utilization efficiency for CO₂,but also had good adaptability to low light environment.It could survive in the pH range of 4.0 to 9.0.The soil environment of pH4.0 and pH9.0 caused damage to it.Its suitable soil pH range was pH5.0-pH8.0.Moderate shading could effectively alleviate the stress of high temperature and strong light on the leaves of Phalaris arundinacea var.Picta,and it had the best growth condition under 70%shading conditions,and 90%shading would cause damage to it.