Effects Of Aeration Cultivation On Root Architecture And The Growth Of Peach Trees

Peach trees have shallow root system and the root respiration rate is high, which requires large amounts of oxygen. Soil oxygen content is important for the growth of peach tree root. This study was conducted to evaluate the effects of aeration cultivation on lateral root growth, root nitrogen metabolism and growth of young peach trees. We studied of Bag-control Urea Peroxide effects on alleviation influence of waterlogging stress damage in young peach trees and the effects of differents aeration methods of the using root control device and soil conditioner concentration application on root architecture, 15 N absorption and utilization and growth of peach trees. We preliminary studied the influence of the permeability on the gene expression of peach seedling root. The main results were as follows:1 The soil oxygen content decreased and subsequently increased during the growth period, reaching a minimum in August. The rhizosphere soil oxygen content was higher under ventilation treatment than control, and rhizosphere ventilation treatment(ventilation every 3 days) markedly increased the rhizosphere soil oxygen content during the medium growth period and the late growth period. After aeration cultivation, the total root length, total root surface area, number of first lateral roots and second lateral roots, number of tips, total root volume, number of forks, number of cross were increased to some extent. The average length of first lateral roots and root average diameter decreased. The angle between first lateral roots and vertically downward direction was decreased, the number of small angle increased, and root tended to vertically distribution under aeration cultivation. The dry matter of roots which the diameter was less than 2 mm was significantly higher than control and the dry matter of roots which the diameter was greater than 5 mm was decreased under aeration cultivation. The activity of root system, the activities of NR, GOT, GPT and the content of root total nitrogen were higher than the control under rhizosphere ventilation treatment(ventilation every 3 days) and they increased 19.04%, 29.80%, 6.56%, 19.91% and 18.90%, respectively.2 The rhizosphere soil available K and organic matter decreased while the rhizosphere soil available N and available P content increased and the soil enzyme activity(soil sucrase, urease, phosphatase and catalase) was improved under ventilation treatments to some extent. Rhizosphere ventilation treaments improved leaf function and increased the net photosynthetic rate. Rhizosphere ventilation treatment increased the leaf chlorophyll content and leaf protective enzyme activity(Superoxide dismutase, Guaiacol peroxidase and Catalase) in the middle and late growth period. Rhizosphere ventilation treatment(ventilation every 3 days) promoted nutrient absorption and utilization of plant, and the total nitrogen, phosphrous and potassium content of young peach root, shoot and leaf were increased remarkably. The dry matter accumulation and stem of young peach trees were higher than the control under rhizosphere ventilation treatment(ventilation every 3 days).3 The results showed that the soil surface water dissolved oxygen concentration increased after application of urea peroxide. The water dissolved oxygen concent always maintain a high level under the bag control urea peroxide treatment within 7 days after treatment. The application of urea peroxide significantly reduced the decrease amplitude of young peach trees leaf net photosynthetic rate(Pn), stomatal conductance(Gs) and transpiration rate(Tr). 5 days after treatment, the young peach trees leaf performance index(PIABS), maximal photochemical ef?ciency(Fv/Fm) the numbers of active reaction center per unit area(RC/Cso) was significantly higher than control, and the increase ampltitude of the heat dissipation per unit area(DIo/Cso) was significantly lower than control under waterlogging stress. The Chl a、Chl b and Chl(a+b) of young peach trees leaf was significantly increased 10.72%、10.86%、10.87 and 5.71%、4.78%、5.57% respectively than control under application of urea peroxide treatments(T1andT2).Application of urea peroxide enhanced the activities of antioxidant enzyme(superoxide dismutase, peroxidase and catalase) in young peach trees leaves and alleviated the increase ampltitude of MDA in young peach trees leaves. The young peach trees root activity, root proline(Pro) content was significantly higher than control, and the root relative plasma membrane permeability(RMP) and alcohol dehydrogenase(ADH) activity was significantly lower than control under application of urea peroxide treatments.4 The concentrated use soil conditioner(concentrated application of Polyacrylamide and Argri-Sc) show that: After the application of soil conditioner, the soil oxygen content was higher than control in the whole growth period of peach trees. The root activity, leaf chlorophyll content, leaf area and leaf net photosynthetic rate were increased in the middle and late growth period under soil conditioner application treatments. It promoted the growth of new shoot and drunk under soil conditioner application treatments. The leaf protective enzyme activity(Superoxide dismutase, Guaiacol peroxidase and Catalase) in the middle and late growth period was higher than control under application of soil conditioner treatment. It remarkably increased the total root length, the total surface area, total root volume and number of tips and it remarkably increased dry matter accumulation, organ nitrogen content and nitrogen utilization rate of young peach trees under application of soil conditioner treatment. Compared with control, the nitrogen utilization rate significantly increased 24.22% and 10.40% respectively under the application of soil conditioner(application of Polyacrylamide and Argri-Sc). Correlation analysis showed that leaf net photosynthetic rate was significantly positively related with soil oxygen content, the total root length and root surface area. Compared with control, the fruit soluble solid content of mature tree was increased by 10.06% under the application of Polyacrylamide.5 The effectiveness evaluation of local optimization under peach trees canopy showed that: It remarkably decreased the soil bulk density in 0-40 cm optimization area and increased soil content under local optimization treatments. It could induce the occurrence of root system and promote root branch and remarkably increased total root volume, total root length and root surface area. There had more hair root, and the root was much longer and thinner under local optimization using vermiculite, and the root longevity was short. There had more new roots and the new roots were much thicker under local optimization using organic fertilizer, and the root longevity was relatively long. The local optimization could increase the number of absorbing root and extensive root and the ratio of absorbing root to extensive root. It could remarkably increase root activity, specific leaf weight, leaf net photosynthetic rate and fruit soluble solid content under local optimization treatments. The local optimization could decrease the length of autumn shoot but increase the diameter of autumn shoot. The tree growth potential was relatively strong which could effectively prevent the autumn tip mong long under local optimization treatments.6 The effects of root control device on root architecture showed that: The soil oxygen content could always maintained at a higher level, and very close to the atmosphere oxygen content at a horizontal distance from root control device for 5 cm, and a vertical distance from the soil surface for 35 cm. The application of root device could increase the root density and there was numerous of white new roots which were much thicker near to root device. It could increase the total root length, total root surface, number of tips, the leaf chlorophyll content and net photosynthetic rate after the application of root device. It could increase the proportion of thin root(<2 mm) and medium root(2-5 mm) in 20-40 cm soil layer after the application of root device.7 Effects of air permeability on root growth and gene express of peach seedings showed that: Under the condition of water and nutrients sufficient supply, compared with control, the number and the length of first lateral root of peach seedling was significantly reduced by 34.85% and 41.76% respectively, the diameter of first lateral root and the number of second lateral root was significantly increased by 26.83% and 41.14% under sand culture treatment. The results show that air permeability affects a broad range of genes. Overall, 700 genes were down-regulated, 414 genes were up-regulated under sand culture treatment. The air permeability affects genes associated with many biological plant processes, such as the metabolic pathways, the biosynthesis of secondary metabolites, plant–pathogen interactions and plant hormone signal transduction. The express of ppa022797 m,ppa024134m and ppa016264 m which encoding the auxin efflux carrier family was up-regulated under sand culture treatment.