The Effect Of Aerated Irrigation On The Growth Of Two Apple Rootstocks And The Soil Environment In The Root Zone

Good rhizosphere soil environment is an important condition to ensure the normal growth and development of plants.Oxygen in rhizosphere environment is an important factor for the normal growth and development of plants.Malus Hupehensis Rehd and Malus Robusta potted seedlings were used as test materials.Irrigation water with different oxygen content was set up to study the changes of the growth of the two apple rootstocks on the ground,the response of the root system in the underground to the irrigation water with different oxygen content,and the changes of soil enzyme activity and microbial community in the root zone of apple rootstocks.The results show that:1.Under the condition of 101KPa and 25℃,air pump aeration was carried out to increase oxygen in irrigation water The relationship between oxygen content in 4L irrigation water and aeration time was y=-0.0025x²+0.2072x+1.8544（R²=0.9025）.2.To improve the oxygen content in irrigation water,the plant height,ground diameter and dry weight of potted Malus Hupehensis Rehd and Malus Robusta can be increased in different degrees,among which the treatment of oxygen content in irrigation water of 5±0.1mg/L is the best.From July to September,the plant height of P2（Oxygen content is 3±0.1mg/L）treatment was significantly increased by 7.8%、24.1%and 15%compared with P1（Oxygen content is 1±0.1mg/L）treatment,the ground diameter of P3（Oxygen content is 5±0.1mg/L）treatment was significantly increased by 28.6%、35%and 33.4%compared with P1treatment,and the dry weight of B3（Oxygen content is 5±0.1mg/L）treatment was significantly increased by 40.3%、30.5%and 26.1%compared with B1（Oxygen content is 1±0.1mg/L）treatment.As the main hub of nutrient and water transport between the underground part and the crown of fruit trees,the thickness of the trunk directly affects the photosynthetic and fluorescence properties of the leaves above the ground.In July,there was no significant difference in chlorophyll content and intercellular CO₂ concentration among three kinds of irrigation water with different oxygen content.From August to September,increasing the oxygen content in irrigation water could improve the photosynthetic fluorescence characteristics of leaves in different degrees.The photosynthetic fluorescence characteristics of the treatment with oxygen content of 5±0.1mg/L were higher than that of the treatment with oxygen content of 3±0.1mg/L and higher than that of the treatment with oxygen content of 1±0.1mg/L.Therefore,the increase of oxygen irrigation can enhance the tree potential,increase the aboveground biomass,increase the chlorophyll content of leaves,enhance the photosynthetic fluorescence characteristics,and improve the ability of stress resistance.3.Three kinds of oxygen content of irrigation water were used to irrigate potted Malus Hupehensis Rehd and Malus Robusta.When the oxygen content of irrigation water was 5±0.1mg/L,the content of N、P、K、Ca、Mg、Fe and Zn in leaves of plants could be significantly increased.Compared with P1,P3 increased by 33.9%、11.4%、37.6%、27.5%、29.5%、43.8%and 8.5%respectively.Compared with B1,B3 increased respectively by 30.6%、23%、42.8%、21.3%、21.9%、39.8%、11.4%。4.With the increase of oxygen content in irrigation water,the root system of Malus Hupehensis Rehd and Malus Robusta seedlings grew more obviously;the root length,root surface area,root tip number and root respiration rate of the treatment with oxygen content of5±0.1mg/L in irrigation water were significantly higher than those of the treatment with oxygen content of 3±0.1mg/L and 1±0.1mg/L in irrigation water;the root enzyme activities of the treatment with oxygen content of 5±0.1mg/L in irrigation water were all significantly higher than those of the treatment with oxygen content of 3±0.1mg/L and 1±0.1mg/L in irrigation water.The root enzyme activity of irrigation water with oxygen content of 5±0.1mg/L was significantly higher than that of irrigation water with oxygen content of 1±0.1mg/L.However,in July,there was no significant difference in SOD activity between P1and P2,B2 and B3,but no significant difference in POD activity between P2 and P3,B1 and B2（Oxygen content is 3±0.1mg/L）,and no significant difference in CAT activity between P1 and P2,B2 and B3.5.The oxygen content in irrigation water is different,and the rhizosphere soil environment of potted Malus Hupehensis Rehd and Malus Robusta is also different.Compared with the treatment with oxygen content of 1±0.1mg/L,the treatment with oxygen content of 5±0.1mg/L in irrigation water can significantly improve the activity of soil invertase,soil urease and soil phosphatase.In addition,increasing the oxygen content of irrigation water can improve the microbial structure of soil,reduce harmful microorganisms and increase beneficial microorganisms;in July-September,the number of soil bacteria in P3treatment was significantly increased by 58.1%,39.7%and 29.5%compared with P1;in August-September,the number of soil fungi in B3 treatment was significantly reduced by28.8%and 35%compared with B1,and the number of soil actinomycetes treated with B3 was significantly higher than that of B1 by 15.8%and 31.6%,respectively.