Effects Of Lignin On Growth And Soil Environment Of Potted Malus Hupehensis Rehd. Under Applying Organic Manure

In this article, the study was carried out to discuss the effects of lignin on growth and soil environment of potted Malus hupehensis Rehd. under applying organic manure. The study based on adopting the method of a pot experiment and laboratory analysis by using one-year Malus hupehensis Rehd. as experimental material. Field determination of potted plant related physiological indicators, then the soil nutrients and soil enzyme activities were detected by collecting rhizosphere and non- rhizosphere soil in underground part. We also probed into the changes of microorganism in rhizosphere soil of Malus hupehensis Rehd.. This study was aimed at expanding the possible utilization of lignin in agriculture and forestry, and providing a theoretical basis for the regulation of root zone soil micro-ecology environment. The results obtained are listed as follows:1. Under 10% organic manure, compared to 2.5 g·kg-1 lignin treatment, the plant height, stem diameter, leaf net photosynthetic rate and relative chlorophyll content were all improved significantly with lignin addition of 1.5 g·kg-1. At the same time,the two concentrations of lignin could improve the root activity to some extent,and the maximum increase was 2.5 g·kg-1 lignin treatment. Under 40% organic manure, lignin was beneficial to the aboveground growth and improve the root activity in underground part of Malus hupehensis Rehd., especially 2.5 g·kg-1 lignin treatment was the most significant.2. After applying organic manure, the soil nutrient contents improved with addition of lignin. But there were different degrees of increase in soil nutrient content due to different levels of organic manure and different concentrations of lignin. Under 10% organic manure, lignin increased the contents of soil organic matter and soil available P, the results at 2.5 g·kg-1 lignin treatment were the most significant. 1.5 g·kg-1 lignin treatment improved rhizosphere soil available K content and non-rhizosphere soil alkaline N content significantly, while 2.5 g·kg-1 lignin treatment increased non-rhizosphere soil available K content and rhizosphere soil alkaline N content significantly. The contents of available P and soil organic matter were in the following decreasing order: the rhizosphere soil > non-rhizosphere soil, the sequence of root soil alkaline N and soil available K content was another order: non-rhizosphere soil> rhizosphere soil. Under 40% organic manure, two concentrations of lignin raised the contents of soil alkaline N and soil available P, their results of 1.5 g·kg-1 lignin treatment were superior to that of 2.5 g·kg-1 lignin treatment. Soil organic matter increased the most with 2.5 g·kg-1 lignin treatment, while its soil available K content was the lowest among the three treatments. The results of soil alkaline N, available K content and organic matter showed that non-rhizosphere soil<rhizosphere soil. However, the content of available P in rhizosphere soil was lower than that in non-rhizosphere soil.3. After applying organic manure, there were changes on enzyme activities due to different content of organic manure and different concentration of lignin to some extent. A significant increase was observed with soil dehydrogenase, invertase and protease activities after adding lignin under 10% organic manure, 1.5 g·kg-1 lignin treatment was the most significant in rhizosphere soil while 2.5 g·kg-1 lignin treatment was the most significant in non- rhizosphere soil among these treatments. The two concentrations of lignin could inhibit the activities of root soil urease and cellulose activity, at the same time, they could improve the root soil alkaline phosphatase, among which the addition of lignin at 2.5 g·kg-1 was the most obvious.Under 40% organic manure, two concentrations of lignin could improve soil invertase, dehydrogenase, cellulose and protease activities, among which the addition of lignin at 1.5 g·kg-1 increased protease activities most obvious, while 2.5 g·kg-1 improve the other enzyme activities the most significantly. The change of root soil urease and alkaline phosphatase activity is stable after adding lignin, the rhizosphere effect of 2.5 g·kg-1 lignin was the largest. No matter 10% or 40% organic manure, soil urease, dehydrogenase, protease, alkaline phosphatase and invertase activity of non- rhizosphere were lower than those of rhizosphere soil, while the cellulose activity of rhizosphere soil was lower than that of non-rhizosphere.4. The number of microorganisms varied due to the concentrations of lignin. Compared to 2.5 g·kg-1 lignin treatment, the 1.5 g·kg-1 lignin treatment could significantly increase the number of bacteria, fungi, actinomycetes of rhizosphere soil to some extent under 10% organic manure. Under 40% organic manure, the two concentrations of lignin could enlarge the number of soil bacteria, fungi, actinomycetes and microbial diversity of rhizosphere soil,and the maximum increase was 2.5 g·kg-1 lignin treatment.To sum up, in terms of improving growth and soil environment of Malus hupehensis Rehd., the experimental research showed that appropriate concentration of lignin was beneficial for the improvement of plant growth and root soil under applying organic manure.