COMPLEXING AGENT FOR PROMOTING DECOMPOSITION OF LOQUAT LEAF LITTER

Abstract

The present invention discloses a complexing agent for promoting decomposition of loquat leaf litter, which belongs to the technical field of plant science. According to the present invention, the mixed solution of Pseudomonas solution, lignin peroxidase, and leucine aminopeptidase solution is applied to the loquat leaf litter, and after in-situ decomposition for four months, the mass loss rate and the decomposition constant of the loquat leaf litter are significantly increased, thereby effectively promoting the decomposition of the loquat leaf litter. The present invention first proposes that the decomposition of the loquat leaf litter is influenced by externally applying a combination agent of enzyme and bacterial solution, which is simple in operation, and promotes the decomposition of the loquat leaf litter while increasing the speed of returning organic matters to soil, thereby improving soil fertility.

Claims

1. A complexing agent for promoting decomposition of loquat leaf litter, comprising leucine aminopeptidase, lignin peroxidase, and Pseudomonas solution, wherein a mass-to-volume ratio of the leucine aminopeptidase, the lignin peroxidase, and the Pseudomonas solution is 5 kg: 5 kg: 5 ml.

2. The complexing agent according to claim 1, wherein the enzyme activity of the leucine aminopeptidase and the lignin peroxidase is greater than or equal to 20 units/mg.

Description

DESCRIPTION OF DRAWINGS

[0028] To more clearly describe the technical solutions in the embodiments of the present invention or in the prior art, the drawings required to be used in the description of the embodiments or the prior art will be simply presented below. Apparently, the drawings in the following description are merely the embodiments of the present invention, and for those ordinary skilled in the art, other drawings can also be obtained according to the provided drawings without contributing creative labor.

[0029] FIG. 1 is a diagram for an in-situ decomposition test of the present invention.

DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be clearly and fully described below in combination with the drawings in the embodiments of the present invention. Apparently, the described embodiments are merely part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those ordinary skilled in the art without contributing creative labor will belong to the protection scope of the present invention.

[0031] In the present invention, Pseudomonas solution, lignin peroxidase, and leucine aminopeptidase have no special models. The products commonly available on the market can be used.

Embodiment 1

[0032] Initial physical and chemical properties of loquat leaf litter

[0033] The initial physical and chemical indicators (total carbon, total nitrogen, total potassium, cellulose content, and lignin content) of the loquat leaf litter were measured, with the results as shown in Table 1.

TABLE-US-00001 TABLE 1 Initial Physical and Chemical Properties of Loquat Leaf Litter Total Total Total carbon nitrogen potassium Cellulose Lignin (g/kg) (g/kg) (g/kg) (%) (%) Loquat leaf litter 464 16.5 14 19 24

Embodiment 2

[0034] Research on effects of laccase, lignin peroxidase and leucine aminopeptidase on decomposition of loquat leaf litter

[0035] A single enzyme (with a concentration of 10 mg/g litter) was applied to the surface of the loquat leaf litter. The application mode was to dissolve the enzyme in water to prepare enzyme solution, then spray the enzyme solution evenly on the surface of the loquat leaf litter (wherein the mass-to-volume ratio of enzyme to water was 1:500 g/ml), decompose for 117 days in a constant temperature and humidity environment (an incubator: temperature of 35 C., and humidity of 75%), measure the mass of the loquat leaf litter before and after the deposition, and calculate the mass loss rate and the decomposition constant.

[0036] The mass residual rate was calculated using the following formula:

[00001]$\begin{array}{cc}{M}_R=M_t/M_{0}100\%& \left(1\right)\end{array}$ [0037] where: M.sub.R indicates the mass residual rate, M.sub.0 indicates the initial mass of litter (g), and M.sub.t indicates the residual mass (g) after litter is decomposed at time t.

[00002]$\begin{array}{cc}\mathrm{Mass}\mathrm{loss}\mathrm{rate}=1-\mathrm{mass}\mathrm{residual}\mathrm{rate}& \left(2\right)\end{array}$

[0038] The decomposition rate was calculated using an Olson negative exponential decay model:

[00003]$\begin{array}{cc}y=e^{-\mathrm{kt}}& \left(3\right)\end{array}$ [0039] where: t indicates the time (day), y indicates the mass residual rate at t, and k indicates the decomposition constant.

[0040] The results were shown in Table 2.

TABLE-US-00002 TABLE 2 Effects of Different Enzymes on Decomposition of Loquat Leaf Litter Mass Decomposition Group Treatment method loss rate constant Experimental Applying laccase 28.20% 0.0028 Group 1 Experimental Applying lignin peroxidase 30.94% 0.0032 Group 2 Experimental Applying leucine 34.00% 0.0033 Group 3 aminopeptidase Control Applying water 23.68% 0.0023 Group 1

[0041] The results showed that compared with the control group 1, the mass loss rates in the experimental groups 1-3 were higher, and P was less than 0.05, which indicated that the mass loss rate of the loquat leaf litter could be significantly improved in the experimental groups 1-3. Compared with the control group 1, the decomposition constants in the experimental groups 1-3 were also significantly improved. That is: the solutions of the experimental groups 1-3 could significantly promote the decomposition of the loquat leaf litter. Wherein the solution of applying leucine aminopeptidase has the best effect in promoting decomposition, and the mass loss rate is increased by 10.32% compared with the control group 1. The mass loss rate is increased by 4.52% and 7.26% respectively by applying laccase and lignin peroxidase compared with the control group 1, which also has obvious effect in promoting decomposition.

[0042] To sum up, the decomposition of the loquat leaf litter could be significantly promoted by applying the lignin peroxidase solution, the leucine aminopeptidase solution, and the laccase solution to the loquat leaf litter, and decomposing for 117 days.

Embodiment 3

[0043] Effects of nitrogen fertilizer, phosphorus fertilizer and trace element fertilizer on decomposition of loquat leaf litter

[0044] A single fertilizer (nitrogen fertilizer, phosphorus fertilizer, and trace element fertilizer) (with a concentration of 50 mg/g litter) was applied to the surface of the loquat leaf litter. The application method was to dissolve the fertilizer in water to prepare a fertilizer solution, then spray the fertilizer solution evenly on the surface of the loquat leaf litter (wherein the mass-to-volume ratio of fertilizer to water was 50:50 mg/ml), decompose for 36 days (at the temperature of 25-30 C. and the humidity of 30-50%), measure the mass of the loquat leaf litter before and after the deposition, and calculate the mass loss rate and the decomposition constant.

[0045] The results were shown in Table 3.

TABLE-US-00003 TABLE 3 Effects of Different Fertilizers on Decomposition of Loquat Leaf Litter Mass Decomposition Group Treatment method loss rate constant Experimental Applying nitrogen fertilizer 15.97% 0.0045 Group 4 Experimental Applying phosphate fertilizer 9.84% 0.0029 Group 5 Experimental Applying trace element fertilizer 5.44% 0.0015 Group 6 Control Applying water 7.19% 0.0026 Group 1

[0046] The results showed that the mass loss rate and the decomposition constant in the experimental group 4 were the highest compared with the control group 1. That is: the solution of applying the nitrogen fertilizer on the surface of the loquat leaf litter in the experimental group 4 could promote the decomposition of the loquat leaf litter. Wherein the mass loss rate was increased by 8.78% compared with the control group 1.

[0047] To sum up, the decomposition of the loquat leaf litter could be significantly promoted by applying the nitrogen fertilizer to the loquat leaf litter and decomposing for 36 days.

Embodiment 4

[0048] Effects of added Pseudomonas solution on decomposition of loquat leaf litter under different temperatures and humidities

[0049] Pseudomonas solution was dissolved in pure water at a ratio of 1 ml of bacterial solution to 1 L of water to obtain diluted bacterial solution. According to the concentration of 10 ml of diluted bacterial solution per 1 kg of litter, under three constant temperatures and humidities, the Pseudomonas solution (diluted) was added separately to the surface of the loquat leaf litter for decomposing for 60 days. The mass of the loquat leaf litter before and after decomposition was measured, and the mass loss rate and the decomposition constant were calculated.

[0050] The results were shown in Table 4.

TABLE-US-00004 TABLE 4 Effects of Pseudomonas Solution on Decomposition of Loquat Leaf Litter Under Different Temperatures and Humidities Mass Components Temperature loss Decomposition Group applied and humidity rate constant Experimental Pseudomonas 35 C., 75% 26.7% 0.0052 Group 7 solution Experimental Pseudomonas 25 C., 80% 23.1% 0.0044 Group 8 solution Experimental Pseudomonas 14 C., 68% 17.0% 0.0031 Group 9 solution Control Distilled water 35 C., 75% 12.0% 0.0021 Group 1 Control Distilled water 25 C., 80% 11.2% 0.0020 Group 2 Control Distilled water 14 C., 68% 10.7% 0.0019 Group 3

[0051] The results showed that the mass loss rate and the decomposition constant of the loquat leaf litter were increased by applying the Pseudomonas solution to the surface of the loquat leaf litter under three temperatures and humidities. The decomposition of the loquat leaf litter could be significantly promoted by applying the Pseudomonas solution to the loquat leaf litter and decomposing for 60 days.

Embodiment 5

[0052] Effects of different combinations of mixed solutions of laccase, lignin peroxidase and leucine aminopeptidase on the decomposition of loquat leaf litter at natural temperature in the field environment

[0053] The loquat leaf litter was decomposed for 150 days in the natural environment (a daytime temperature of 155 C., with a humidity of 755%; a nighttime temperature of 53 C., with a humidity of 405%), to verify the effect of the mixed enzyme solution on promoting decomposition. (The concentration was still 10 mg/g litter, and each enzyme is 10 mg, that is, taking experimental group 10 as an example, the three enzymes were added with 10 mg/g litter). The mass of the loquat leaf litter before and after decomposition was measured, and the mass loss rate and the decomposition constant were calculated.

[0054] The results were shown in Table 5.

TABLE-US-00005 TABLE 5 Effects of Mixed Enzyme on Decomposition of Loquat Leaf Litter Mass loss rate Decomposition Group Solution added (%) constant Experimental Mixed solution of laccase + 24.78 0.0019 Group 10 lignin peroxidase + leucine aminopeptidase Experimental Mixed solution of laccase + 22.37 0.0017 Group 11 leucine aminopeptidase Experimental Mixed solution of lignin 23.25 0.0018 Group 12 peroxidase + leucine aminopeptidase Experimental Mixed solution of laccase + 25.44 0.0020 Group 13 lignin peroxidase Control Water 21.49 0.0016 Group 1

[0055] The results showed that when the loquat leaf litter in the experimental groups 10-13 was decomposed in situ to 150 days in the natural environment, the mass loss rates and the decomposition constants thereof were higher than those in the control group 1. It showed that the experimental groups 10-13 had the effect in promoting the decomposition of the loquat leaf litter. After decomposing for 150 days according to the technical solution, the mass loss rate was increased from 21.49% to 22.37%-25.44%, and the decomposition constant was increased from 0.0016 to 0.0017-0.0020. Wherein the experimental group 13 (spraying the mixed solution of laccase and lignin peroxidase) had the best promotion effect. The above results showed that the decomposition of the loquat leaf litter could also be promoted by spraying the mixed solution of laccase, lignin peroxidase and leucine aminopeptidase thereon in the natural environment.

[0056] In an indoor single enzyme test, leucine aminopeptidase and lignin peroxidase had the best comprehensive effect. Meanwhile, considering that laccase and lignin peroxidase had similar effects, i.e., degrading lignin in the litter, one of them was selected to continue the test.

[0057] Comprehensive analysis of the results of embodiments 2-5 was conducted to select the nitrogen fertilizer, leucine aminopeptidase, lignin peroxidase, and Pseudomonas solution that promote the decomposition of the loquat leaf litter, and to design different concentrations and combinations of experiments in order to select the best combination and ratio.

Embodiment 6

[0058] 1. The air-dried, intact and uncorrupted loquat leaf litter was collected from the loquat orchard in Dongshan Town, Wuzhong District, Suzhou City, Jiangsu Province, and 15 g of loquat leaf litter was weighed, put into a decomposition bag and put back in its original position. Three decomposition bags were placed as parallel samples in each embodiment.

[0059] 2. According to the proportions in Table 6, 750 mg of nitrogen fertilizer, 75 mg of lignin peroxidase and 225 mg of leucine aminopeptidase were weighed, mixed and dissolved in 900 mL of water. The mixed solution was evenly sprayed on the surface of the loquat leaf litter.

[0060] 3. Pseudomonas solution was dissolved in pure water at a ratio of 1 ml of bacterial solution to 1 L of water for dilution, and 0.15 ml of diluted bacterial solution was sprayed on the surface of the loquat leaf litter according to Table 6. (Because the volume of the bacterial solution is too small, 0.15 ml of diluted bacterial solution could be dissolved in 100 ml of water again during operation so that it could be sprayed evenly on the litter surface).

[0061] 4. The loquat leaf litter was decomposed for 120 days in the natural environment (a daytime temperature of 155 C., with a humidity of 755%; a nighttime temperature of 53 C., with a humidity of 405%), taken out of the decomposition bag, and weighed after removing the soil attached on the surface. The decomposition constant and the mass loss rate were calculated. The results were shown in Table 7.

Embodiments 7-14

[0062] The embodiments have the same steps as embodiment 6 except for the concentrations of sprayed components in step 2 and step 3 (refer to Table 6). The decomposition time is 120 days. The results of the decomposition constant and the mass loss rate of loquat leaf litter were shown in Table 7.

Control Example 1

[0063] The control example has the same steps as embodiment 6 except for water sprayed on the surface of the loquat leaf litter in step 2 and step 3. The decomposition time is 120 days. The results of the decomposition constant and the mass loss rate of loquat leaf litter were shown in Table 7.

TABLE-US-00006 TABLE 6 Proportion in Embodiments and Control Example Nitrogen Leucine Lignin Pseudomonas fertilizer amino- peroxidase solution mg/g peptidase mg/g ml/kg litter mg/g litter litter litter Embodiment 6 50 15 5 10 Embodiment 7 0 10 15 10 Embodiment 8 50 5 15 15 Embodiment 9 25 5 10 10 Embodiment 10 25 15 15 5 Embodiment 11 0 5 5 5 Embodiment 12 0 15 10 15 Embodiment 13 25 10 5 15 Embodiment 14 50 10 10 5 Control 0 0 0 0 example 1

TABLE-US-00007 TABLE 7 Test Results of Embodiments and Control Example Mass loss rate Decomposition constant Embodiment 6 42.7% 0.0047 Embodiment 7 48.7% 0.0056 Embodiment 8 39.2% 0.0043 Embodiment 9 43.3% 0.0048 Embodiment 10 41.7% 0.0046 Embodiment 11 50.7% 0.0059 Embodiment 12 43.3% 0.0051 Embodiment 13 40.0% 0.0043 Embodiment 14 38.0% 0.0040 Control example 1 30.0% 0.0030

[0064] When the loquat leaf litter in the embodiments 6-14 was decomposed to 18 days, the mass loss rates and decomposition rate constants were higher than those in the control example 1. It showed that the embodiments 6-14 had the effect in promoting the decomposition of the loquat leaf litter. After decomposing for 120 days according to the technical solution, the mass loss rate was increased from 30.0% to 38.0%-50.7%, and the decomposition constant was increased from 0.0030 to 0.0040-0.0059. Wherein embodiments 7 and 11 had the best promotion effect.

[0065] The above results show that the decomposition of the loquat leaf litter can be promoted by spraying the mixed solution of nitrogen fertilizer, Pseudomonas, lignin peroxidase, and leucine aminopeptidase thereto in the natural environment. Different proportions have different promotion effects. Considering the cost, embodiment 11 (no nitrogen fertilizer is used, and the concentrations of enzyme and bacteria are 5 mg of enzyme per gram of litter and 5 ml of bacterial solution per kilogram of litter, respectively) has the best comprehensive effect.

[0066] It can be seen from the above embodiments that the technical solution of the present invention can increase the mass loss rate of the loquat leaf litter (by 8%-20.7%), and effectively promote the decomposition of the loquat leaf litter.

[0067] Each embodiment in the description is described in a progressive way. The difference of each embodiment from each other is the focus of explanation. The same and similar parts among all of the embodiments can be referred to each other.

[0068] The above description of the disclosed embodiments enables those skilled in the art to realize or use the present invention. Many modifications to these embodiments will be apparent to those skilled in the art. The general principle defined herein can be realized in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principle and novel features disclosed herein.