Method for determining utilization efficiency and utilization share of inorganic nitrogen of coix lacryma-jobi seedlings

Abstract

The invention discloses a method for measuring the utilization efficiency and utilization share of inorganic nitrogen of coix lacryma-jobi seedlings. The method comprises the following steps: planting the coix lacryma-jobi seedlings in a mixed nitrogen source consisting of high-abundance 15N marked ammonium nitrogen and natural-abundance nitrate nitrogen; calculating the ammonium nitrogen utilization share of the overground part and the underground part of the coix lacryma-jobi seedling, and calculating the ammonium nitrogen accumulation amount of the overground part and the underground part of the coix lacryma-jobi seedling; calculating the nitrate nitrogen accumulation amount of the coix lacryma-jobi seedlings in the whole experimental treatment; the molar weight of nitrate nitrogen and the molar weight of ammonium nitrogen supplied in the whole culture period are calculated, and the nitrate nitrogen utilization efficiency and the ammonium nitrogen utilization efficiency of the coix lacryma-jobi seedlings are calculated. Besides, on the basis of the ammonium nitrogen accumulation amount and the nitrate nitrogen accumulation amount of the coix lacryma-jobi seedlings in the whole culture period, the nitrate nitrogen utilization share and the ammonium nitrogen utilization share of the coix lacryma-jobi seedlings can be quantified, and the utilization difference of the nitrate nitrogen and the ammonium nitrogen of the coix lacryma-jobi seedlings under different inorganic nitrogen supply conditions is revealed; and a scientific basis is provided for deeply knowing an inorganic nitrogen utilization strategy of the coix lacryma-jobi seedlings.

Description

Technical Field

[0001] The invention relates to a method for measuring the inorganic nitrogen utilization efficiency and utilization share of coix seedlings, and belongs to the technical field of agricultural production. Background Art

[0002] Nitrogen is an essential nutrient for plant growth and development and a key component of proteins, nucleic acids, enzymes, and chlorophyll. The inorganic nitrogen absorbed and utilized by plants from the soil primarily comes in the form of nitrate and ammonium. However, due to long-term cultivation, the soils where coix is cultivated may face an insufficient supply of inorganic nitrogen. Insufficient inorganic nitrogen in the soil will hinder the growth and development of coix, while excessive fertilization may lead to inorganic nitrogen waste and even environmental problems. Therefore, studying the utilization of inorganic nitrogen during coix seedling growth is particularly important. Quantifying the proportion and efficiency of nitrate and ammonium nitrogen utilization by coix seedlings during their growth stage will provide a theoretical basis for scientifically managing the inorganic nitrogen supply during the coix seedling stage. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for determining the inorganic nitrogen utilization efficiency and utilization share of coix seedlings, quantify the share and efficiency of nitrate nitrogen and ammonium nitrogen utilization during the growth stage of coix seedlings, and fill the gap of inability to accurately fertilize during the growth process of coix seedlings.

[0004] The technical solution of the present invention is: a method for determining the inorganic nitrogen utilization efficiency and utilization share of coix seedlings, comprising the following steps: first, high abundance 15 N-labeled ammonium nitrogen (NH4Cl, 10atom% 15 N), calculated as high abundance 15 The stable nitrogen isotope value of ammonium nitrogen labeled by N is denoted as δ 15 N a The stable nitrogen isotope value of the purchased natural abundance nitrate nitrogen was measured by stable isotope mass spectrometry and recorded as δ 15 N n ; High abundance 15 Coix seedlings were cultured in a mixed nitrogen source nutrient solution consisting of N-labeled ammonium nitrogen and naturally abundant nitrate nitrogen. The other components of the nutrient solution were as follows: 1 mM MgSO4·7H2O, 0.125 mM KH2PO4, 2.5 mM KCl, 2 mM CaCl2·2H2O, 0.1875 mM K2SO4, 50 μM Fe(Na)EDTA, 25 μM H3BO3, 2 μM MnSO4·1H2O, 2 μM ZnSO4·7H2O, 0.1 μM CuSO4·5H2O, 0.04 μM CoCl2·6H2O, 0.1 μM Na2MoO4·2H2O;

[0005] Second, the coix seedlings were cultured in the same culture room to ensure that the culture conditions were exactly the same and the high abundance 15 N-labeled ammonium nitrogen and naturally abundant nitrate nitrogen were from the same manufacturer and batch;

[0006] Third, cultivating the coix seedlings with uniform growth in the above nutrient solution;

[0007] Fourth, similarly, before the experimental treatment, four coix seedlings with the same growth were randomly selected, and the dry weight, nitrogen content and stable nitrogen isotope value of the aboveground and underground parts of these four seedlings were measured respectively; the average dry weight, average nitrogen content and average stable nitrogen isotope value of the aboveground and underground parts of these four seedlings were approximately the initial dry weight, initial nitrogen content and initial stable nitrogen isotope value of the aboveground and underground parts of the coix seedlings in the entire experimental treatment; the initial dry weight, initial nitrogen content and initial stable nitrogen isotope value of the aboveground part of the coix seedlings were recorded as DW, s0 、N s0 and δ 15 N s0 The initial dry weight, initial nitrogen content and initial stable nitrogen isotope value of the underground part of Coix seedlings were recorded as DW r0 、N r0 and δ 15 N r0 ;

[0008] Fifth, use DW s0 、N s0 、DW r0 and N r0 , calculate the total nitrogen accumulation of the initial whole coix seedling, recorded as m0;

[0009] Sixth, after 12 days of cultivation, the nutrient solution treatment solution was replaced every 2 days, with 1000 ml of the nutrient solution per seedling. The dry weight, nitrogen content, and stable nitrogen isotope value of the aboveground and underground parts of the coix seedlings were measured respectively. The dry weight, nitrogen content, and stable nitrogen isotope value of the aboveground part of the coix seedlings after 12 days of treatment were recorded as DW s1 、N s1 and δ 15 N s1 The dry weight, nitrogen content and stable nitrogen isotope value of the underground part of Coix seedlings were recorded as DW r1 、N r1 and δ 15 N r1 ;

[0010] Seventh, use DW s1 、N s1 、DW r1 and N r1The total nitrogen accumulation of the whole coix seedling after 12 days of cultivation was calculated and recorded as m1;

[0011] Eighth, use DW s1 、N s1 , δ 15 N s1 and δ 15 N a Calculate the ammonium nitrogen accumulation in the aboveground part of coix seedlings after 12 days of cultivation, recorded as m sa ; Using DW r1 、N r1 , δ 15 N r1 and δ 15 N a Calculate the ammonium nitrogen accumulation in the underground part of coix seedlings after 12 days of cultivation, recorded as m ra ;

[0012] Ninth, according to m sa and m ra Calculate the ammonium nitrogen accumulation of the whole coix seedling after 12 days of cultivation, recorded as m a ;

[0013] Tenth, according to the law of conservation of mass, based on m0, m1 and m a The nitrate nitrogen accumulation of the whole coix seedling can be calculated and recorded as m n ;

[0014] Eleventh, calculate the molar amount of ammonium nitrogen supplied during the entire culture period, recorded as n ta ; Based on m a and n ta , the ammonium nitrogen utilization efficiency of the whole coix seedling can be calculated, recorded as NUE a ;

[0015] 12. Calculate the molar amount of nitrate nitrogen supplied during the entire cultivation period, recorded as n tn ; Based on m n and n tn , the ammonium nitrogen utilization efficiency of the whole coix seedling can be calculated, recorded as NUE n ;

[0016] Thirteenth, according to m a and m n , the ammonium nitrogen utilization share and nitrate nitrogen utilization share of the whole coix seedling can be calculated, and recorded as fa and fn respectively.

[0017] Furthermore, in the fifth step, the method for calculating the total nitrogen accumulation of the initial whole-plant coix seedling is as follows: DW s0 、N s0 、DW r0 and Nr0 Substitute into the equation: m0 = DW s0 ×N s0 +DW r0 ×N r0 .

[0018] Furthermore, in the seventh step, the total nitrogen accumulation of the whole coix seedling after 12 days of cultivation is calculated as follows: DW s1 、N s1 、DW r1 and N r1 Substitute into the equation: m1 = DW s1 ×N s1 +DW r1 ×N r1 .

[0019] Furthermore, in the eighth step, the method for calculating the ammonium nitrogen accumulation in the aerial part of the coix seedling is: s1 、N s1 , δ 15 N s1 and δ 15 N a Substitute into the equation: m sa =DW s1 ×N s1 ×δ 15 N s1 / δ 15 N a The method for calculating the ammonium nitrogen accumulation in the underground part of coix seedlings is: r1 、N r1 , δ 15 N r1 and δ 15 N a Substitute into the equation: m ra =DW r1 ×N r1 ×δ 15 N r1 / δ 15 N a .

[0020] Furthermore, in the ninth step, the method for calculating the ammonium nitrogen accumulation of the whole coix seedling is: m sa and m ra Substitute into the equation: m a =m sa +m ra .

[0021] Furthermore, in the tenth step, the method for calculating the nitrate nitrogen accumulation of the whole coix seedling is: m0, m0 and m a Substitute into the equation: m n =m1-m0-ma .

[0022] Furthermore, in the eleventh step, the method for calculating the ammonium nitrogen utilization efficiency of the whole coix seedling is: m a and n ta Substitute into the equation: NUE a =(m a / M a / n ta )×100.

[0023] Furthermore, in the twelfth step, the method for calculating the nitrate nitrogen utilization efficiency of the whole coix seedling is: m n and n tn Substitute into the equation: NUE n =(m n / M n / n tn )×100.

[0024] Furthermore, in the thirteenth step, the method for calculating the ammonium nitrogen utilization share of the whole coix seedling is: m a and m n Substituting into the equation: The method for calculating the nitrate nitrogen utilization share of the whole coix seedling is: n =1-f a .

[0025] Beneficial effects of the present invention: 1) The present invention only requires the use of high abundance 15 N-labeled ammonium nitrogen (NH4Cl, 10atom% 15 N), and then measure the biomass, nitrogen content and stable nitrogen isotope values of the aboveground and underground parts of Coix seedlings, the utilization share and utilization efficiency of nitrate nitrogen and ammonium nitrogen in the whole Coix seedlings can be quantified.

[0026] 2) The present invention can quantitatively evaluate the utilization share and utilization efficiency of nitrate nitrogen and ammonium nitrogen in coix seedlings under different inorganic nitrogen supply conditions, which provides a scientific basis for precise fertilization during the growth stage of coix.

[0027] 3) The present invention is based on the two-terminal isotope mixing model and the law of conservation of mass, and the calculation results are accurate.

[0028] Principle of the Invention

[0029] Based on the two-terminal isotope mixing model, the stable isotope values of the aboveground and underground parts of Coix lachryma-jobi seedlings after cultivation can be expressed by the following equations:

[0030] δ S =f Sa ×δ Sa +f Sn×δ Sn +δ S初始 =f Sa ×δ Sa +(1-f Sa )×δ Sn +δ S初始 (1)

[0031] δ R =f Ra ×δ Ra +f Rn ×δ Rn +δ R初始 =f Ra ×δ Ra +(1-f Ra )×δ Rn +δ R初始 (2)

[0032] Here δ S and δ R are the stable nitrogen isotope values of the aboveground and underground parts of Coix lachryma-jobi seedlings after cultivation; δ Sa is the stable nitrogen isotope value of the aerial part of coix seedlings after stable nitrogen isotope fractionation using highly abundant labeled ammonium nitrogen; δ Ra is the stable nitrogen isotope value of the underground part of coix seedlings after stable nitrogen isotope fractionation using highly abundant labeled ammonium nitrogen; δ Sn is the stable nitrogen isotope value of the aboveground part of coix seedlings after stable nitrogen isotope fractionation using naturally abundant nitrate nitrogen; δ Rn is the stable nitrogen isotope value of the underground part of coix seedlings after stable nitrogen isotope fractionation using naturally abundant nitrate nitrogen; Sa is the proportion of nitrogen utilization from ammonium in the aboveground part of coix seedlings; Ra is the share of ammonium nitrogen utilization in the underground part of coix seedlings; Sn is the share of nitrate nitrogen utilization in the aboveground part of coix seedlings, f Sn =1–f Sa ;f Rn is the share of nitrate nitrogen utilization in the underground part of coix seedlings, f Rn =1–f Ra ; δ S初始 and δ R初始 are the stable nitrogen isotope values of the aboveground and underground parts of Coix lachryma-jobi seedlings at the beginning of the experimental treatment;

[0033] According to equations (1) and (2), the fraction of nitrogen utilization from ammonium in the aerial parts of coix seedlings is f Sa and the share of ammonium nitrogen utilization in the underground part of Coix lachryma-jobi seedlings Ra It can be rewritten as the following equation:

[0034]

[0035] Due to the high abundance 15 N-labeled ammonium nitrogen (NH4Cl, 10atom% 15 The stable nitrogen isotope value of N) is 29222.0‰, while the nitrogen isotope fractionation value caused by plant assimilation of ammonium nitrogen is much lower than that of high abundance. 15 The stable nitrogen isotope value of ammonium nitrogen labeled by N. Therefore, high abundance 15 N-labeled ammonium nitrogen (NH4Cl, 10atom% 15 The stable nitrogen isotope value of the coix seedlings can be approximated as the stable nitrogen isotope value after nitrogen isotope fractionation using ammonium nitrogen, i.e., δ Sa =δ Ra =δ a , δ a =29222.0‰; The stable nitrogen isotope values of plants cultured under natural abundance inorganic nitrogen sources usually vary in the range of -10 to +20‰. Therefore, (1-f Sa )×δ Sn / δ Sa , δ S初始 / δ Sa , (1-f Ra )×δ Rn / δ Ra and δ R初始 / δ Ra The result will be very small and can be ignored. Accordingly, equations (3) and (4) can be approximated as follows:

[0036]

[0037] After quantifying the utilization share of ammonium nitrogen in the aboveground and underground parts of coix seedlings after the end of cultivation, the ammonium nitrogen accumulation in the aboveground and underground parts of coix seedlings can be calculated using the following equation based on the dry weight and nitrogen content of the aboveground and underground parts of coix seedlings after the end of cultivation:

[0038] m Sa =DW S1 ×N S1 ×f Sa (7)

[0039] m Ra =DW R1 ×N R1 ×f Ra (8)

[0040] The m here SaDW is the amount of ammonium nitrogen accumulated in the aboveground part of coix seedlings after the incubation period; s1 is the dry weight of the aboveground part of coix seedlings after the culture; N s1 is the nitrogen content of the aboveground part of coix seedlings after the cultivation; m Ra DW is the amount of ammonium nitrogen accumulated in the underground part of coix seedlings after the culture is completed; R1 is the dry weight of the underground part of coix seedlings after the culture is completed; N R1 It is the nitrogen content in the underground part of coix seedlings after the cultivation is completed.

[0041] According to m Sa and m Ra , the ammonium nitrogen accumulation of the whole coix seedling after the cultivation (m a ) can be calculated by the following equation:

[0042] m a =m Sa +m Ra (9)

[0043] According to the dry weight and nitrogen content of the aboveground and underground parts of the coix seedlings before and after the incubation, the initial and final total nitrogen accumulation of the whole coix seedlings were calculated using the following equations:

[0044] m0=DW s0 ×N s0 +DW r0 ×N r0 (10)

[0045] m1=DW s1 ×N s1 +DW r1 ×N r1 (11)

[0046] Here m0 is the initial total nitrogen accumulation of the whole coix seedling; DW s0 is the initial dry weight of the aboveground part of Coix seedlings; N s0 is the initial nitrogen content of the aboveground part of Coix seedlings; DW r0 is the initial dry weight of the underground part of Coix seedlings; N r0 is the initial nitrogen content of the underground part of the coix seedling; m1 is the final total nitrogen accumulation of the whole coix seedling; DW s1 is the final dry weight of the aboveground part of Coix seedlings; N s1 is the final nitrogen content of the aboveground part of Coix seedlings; DW r1 is the final dry weight of the underground part of Coix seedlings; N r1 It is the final nitrogen content of the underground part of Coix seedlings.

[0047] According to the law of conservation of mass, the nitrate nitrogen accumulation of the whole coix seedling during the entire culture period (m n ):

[0048] m n =m1-m0-m a (12)

[0049] The molar amount of ammonium nitrogen supplied during the entire cultivation period was calculated, and then the ammonium nitrogen utilization efficiency of the entire coix seedling was calculated using the following equation:

[0050] NUE a =(m a / M a / n ta )×100 (13)

[0051] The NUE here a is the ammonium nitrogen utilization efficiency of the whole coix seedling; M a High abundance 15 N-labeled ammonium nitrogen (NH4Cl, 10atom% 15 N) molar mass, M a =14.1g / mol; n ta is the molar amount of ammonium nitrogen supplied during the entire culture period.

[0052] The molar amount of nitrate nitrogen supplied during the entire cultivation period was calculated, and then the nitrate nitrogen utilization efficiency of the entire coix seedling was calculated using the following equation:

[0053] NUE n =(m n / M n / n tn )×100 (14)

[0054] The NUE here n is the nitrate nitrogen utilization efficiency of the whole coix seedling; M n is the molar mass of nitrate nitrogen (NaNO3) at natural abundance, M n =14.0g / mol; n tn is the molar amount of nitrate nitrogen supplied during the entire cultivation period.

[0055] According to m a and m n , the utilization ratio of ammonium nitrogen in the whole coix seedling (f a ) can be calculated using the following equation:

[0056]

[0057] Correspondingly, the nitrate nitrogen utilization share of the whole coix seedling is f nThat is 1–f a . DETAILED DESCRIPTION

[0058] High abundance 15 The stable nitrogen isotope values of N-labeled inorganic nitrogen sources differ significantly from those of naturally abundant inorganic nitrogen sources. 15 N-labeled ammonium nitrogen (NH4Cl, 10atom% 15 The stable nitrogen isotope value of N) is 29222.0‰, while the nitrogen isotope fractionation value caused by plant assimilation of ammonium nitrogen is much lower than that of high abundance. 15 The stable nitrogen isotope value of ammonium nitrogen labeled by N. Therefore, high abundance 15 N-labeled ammonium nitrogen (NH4Cl, 10atom% 15 The stable nitrogen isotope value of the plant can be approximated as the stable nitrogen isotope value after the plant utilizes ammonium nitrogen to undergo nitrogen isotope fractionation. The stable nitrogen isotope value of plants cultured under natural abundance inorganic nitrogen sources usually varies in the range of -10 to +20‰. Therefore, when coix seedlings are planted in high abundance 15 When the nitrogen source is a mixture of N-labeled ammonium nitrogen and naturally abundant nitrate nitrogen, the abundance of the aboveground part of the coix seedlings is high after the incubation. 15 The proportion of N-labeled ammonium nitrogen is approximately the sum of the stable nitrogen isotope value and the high abundance of nitrogen in the aboveground part. 15 N-labeled ammonium nitrogen (NH4Cl, 10atom% 15 The ratio of the stable nitrogen isotope values of N) is higher in the underground part of coix seedlings. 15 The proportion of N-labeled ammonium nitrogen is approximately the sum of the stable nitrogen isotope value and the high abundance of 15 N-labeled ammonium nitrogen (NH4Cl, 10atom% 15 In the present invention, the present invention relates to the nitrate nitrogen accumulation amount of coix seedlings aboveground part and underground part according to the dry weight and nitrogen content of coix seedlings aboveground part and underground part after cultivating. Correspondingly, according to the dry weight and nitrogen content of coix seedlings aboveground part and underground part after cultivating, the ammonium nitrogen accumulation amount of coix seedlings aboveground part and underground part can be calculated respectively. According to the dry weight and nitrogen content of coix seedlings aboveground part and underground part before and after the experimental treatment, the total nitrogen accumulation amount before and after the experimental treatment of coix seedlings can be calculated. So, according to the law of conservation of mass, the nitrate nitrogen accumulation amount of whole strain coix seedlings after cultivating can be calculated. Then, according to the nitrate nitrogen and ammonium nitrogen molar weight of supply during the incubation period, the nitrate nitrogen utilization efficiency and the ammonium nitrogen utilization efficiency of whole strain coix seedlings can be calculated, which provides a theoretical basis for the supply of inorganic nitrogen in the scientific management coix seedling stage.

[0059] Under mixed nitrogen source culture, the total nitrogen accumulation of coix seedlings comes from the utilization of nitrate nitrogen and ammonium nitrogen. Therefore, based on the nitrate nitrogen accumulation and ammonium nitrogen accumulation of the entire coix seedling throughout the culture period, the nitrate nitrogen utilization share and ammonium nitrogen utilization share of the entire coix seedling can be quantified, thereby revealing the differences in nitrate nitrogen and ammonium nitrogen utilization of coix seedlings under different inorganic nitrogen supply conditions. This provides a scientific basis for a deeper understanding of the inorganic nitrogen utilization strategy of coix seedlings.

[0060] An embodiment of the present invention comprises the following steps:

[0061] First, buy high abundance 15 N-labeled ammonium nitrogen (NH4Cl, 10atom% 15 N), calculated as high abundance 15 The stable nitrogen isotope value of ammonium nitrogen labeled by N is denoted as δ 15 N a The stable nitrogen isotope value of the purchased natural abundance nitrate nitrogen was measured by stable isotope mass spectrometry and recorded as δ 15 N n ; High abundance 15 Coix seedlings were cultured in a mixed nitrogen source nutrient solution consisting of N-labeled ammonium nitrogen and naturally abundant nitrate nitrogen. The other components of the nutrient solution were as follows: 1 mM MgSO4·7H2O, 0.125 mM KH2PO4, 2.5 mM KCl, 2 mM CaCl2·2H2O, 0.1875 mM K2SO4, 50 μM Fe(Na)EDTA, 25 μM H3BO3, 2 μM MnSO4·1H2O, 2 μM ZnSO4·7H2O, 0.1 μM CuSO4·5H2O, 0.04 μM CoCl2·6H2O, 0.1 μM Na2MoO4·2H2O;

[0062] Second, the coix seedlings were cultured in the same culture room to ensure that the culture conditions were exactly the same and the high abundance 15 N-labeled ammonium nitrogen and naturally abundant nitrate nitrogen were from the same manufacturer and batch;

[0063] Third, cultivating the coix seedlings with uniform growth in the above nutrient solution;

[0064] Fourth, similarly, before the experimental treatment, four coix seedlings with the same growth were randomly selected, and the dry weight, nitrogen content, and stable nitrogen isotope values of the aboveground and underground parts of these four seedlings were measured. The average dry weight, average nitrogen content, and average stable nitrogen isotope value of the aboveground and underground parts of these four seedlings were approximately the initial dry weight, initial nitrogen content, and initial stable nitrogen isotope value of the aboveground and underground parts of the coix seedlings in the entire experimental treatment; the initial dry weight, initial nitrogen content, and initial stable nitrogen isotope value of the aboveground part of the coix seedlings were recorded as DW, s0 、N s0 and δ 15 N s0 The initial dry weight, initial nitrogen content and initial stable nitrogen isotope value of the underground part of Coix seedlings were recorded as DW r0 、N r0 and δ 15 N r0 ;

[0065] Fifth, use DW s0 、N s0 、DW r0 and N r0 , calculate the initial total nitrogen accumulation of the whole coix seedling, recorded as m0; the method for calculating the initial total nitrogen accumulation of the whole coix seedling is: DW s0 、N s0 、DW r0 and N r0 Substitute into the equation: m0 = DW s0 ×N s0 +DW r0 ×N r0 ;

[0066] Sixth, after 12 days of culture, the nutrient solution was replaced every 2 days, with 1000 ml of nutrient solution per seedling. The dry weight, nitrogen content, and stable nitrogen isotope values of the aboveground and underground parts of the coix seedlings were measured. The dry weight, nitrogen content, and stable nitrogen isotope values of the aboveground parts of the coix seedlings after 12 days of treatment were recorded as DW s1 、N s1 and δ 15 N s1 The dry weight, nitrogen content and stable nitrogen isotope value of the underground part of Coix seedlings were recorded as DW r1 、N r1 and δ 15 N r1 ;

[0067] Seventh, use DW s1 、N s1 、DW r1 and N r1The total nitrogen accumulation of the whole coix seedling after 12 days of cultivation was calculated and recorded as m1. The method for calculating the total nitrogen accumulation of the whole coix seedling after 12 days of cultivation is as follows: DW s1 、N s1 、DW r1 and N r1 Substitute into the equation: m1 = DW s1 ×N s1 +DW r1 ×N r1 ;

[0068] Eighth, use DW s1 、N s1 , δ 15 N s1 and δ 15 N a Calculate the ammonium nitrogen accumulation in the aboveground part of coix seedlings after 12 days of cultivation, recorded as m sa The method for calculating the ammonium nitrogen accumulation in the aboveground part of coix seedlings is as follows: s1 、N s1 , δ 15 N s1 and δ 15 N a Substitute into the equation: m sa =DW s1 ×N s1 ×δ 15 N s1 / δ 15 N a ; Using DW r1 、N r1 , δ 15 N r1 and δ 15 N a Calculate the ammonium nitrogen accumulation in the underground part of coix seedlings after 12 days of cultivation, recorded as m ra The method for calculating the ammonium nitrogen accumulation in the underground part of coix seedlings is: r1 、N r1 , δ 15 N r1 and δ 15 N a Substitute into the equation: m ra =DW r1 ×N r1 ×δ 15 N r1 / δ 15 N a ;

[0069] Ninth, according to m sa and m raCalculate the ammonium nitrogen accumulation of the whole coix seedling after 12 days of cultivation, recorded as m a The method for calculating the ammonium nitrogen accumulation of the whole coix seedling is: m sa and m ra Substitute into the equation: m a =m sa +m ra ;

[0070] Tenth, according to the law of conservation of mass, based on m0, m1 and m a Calculate the nitrate nitrogen accumulation of the whole coix seedling, recorded as m n The method for calculating the nitrate nitrogen accumulation of the whole coix seedling is: m0, m1 and m a Substitute into the equation: m n =m1-m0-m a ;

[0071] Eleventh, calculate the molar amount of ammonium nitrogen supplied during the entire culture period, recorded as n ta ; Based on m a and n ta , the ammonium nitrogen utilization efficiency of the whole coix seedling can be calculated, recorded as NUE a The method for calculating the ammonium nitrogen utilization efficiency of the whole coix seedling is: m a and n ta Substitute into the equation: NUE a =m a / M a / n ta ;

[0072] 12. Calculate the molar amount of nitrate nitrogen supplied during the entire cultivation period, recorded as n tn ; Based on m n and n tn , the nitrate nitrogen utilization efficiency of the whole coix seedling can be calculated, recorded as NUE n The method for calculating the nitrate nitrogen utilization efficiency of the whole coix seedling is: m n and n tn Substitute into the equation: NUE n =m n / M n / n tn ;

[0073] Thirteenth, according to m a and m n , the ammonium nitrogen utilization share and nitrate nitrogen utilization share of the whole coix seedling can be calculated, which are denoted as f a and f n The method for calculating the ammonium nitrogen utilization share of the whole coix seedling is: a and m nSubstituting into the equation: The method for calculating the nitrate nitrogen utilization share of the whole coix seedling is: n =1-f a .

[0074] Example 1:

[0075] Culture material: Coix seedlings with uniform growth

[0076] Culture conditions: The improved 1 / 2 Hoagland nutrient solution was used to culture the coix seedlings. The nitrate nitrogen in the Hoagland nutrient solution was sodium nitrate, and its stable nitrogen isotope value was 22.2‰; the ammonium nitrogen in the Hoagland nutrient solution was highly abundant. 15 N-labeled ammonium nitrogen (NH4Cl, 10atom% 15 The light intensity in the culture room was 500 ± 25 μmol m -2 s -1 The temperature was 25±2°C during light exposure and 19±2°C at night. The relative humidity was 55-60%. The pH of the culture medium was 7.3±0.1, and air was introduced into the culture medium using an aerator. The total nitrogen concentration gradient in the Hoagland nutrient solution was set to 0.5mM, 1mM, and 2mM. The ratio of nitrate nitrogen to ammonium nitrogen in each total nitrogen concentration gradient was 1:1, that is, the nitrate nitrogen concentration and ammonium nitrogen concentration in the three total nitrogen concentration gradients were 0.25mM, 0.5mM, and 1mM, respectively. The other ingredients of the improved 1 / 2 Hoagland nutrient solution are as follows: 1mM MgSO4·7H2O, 0.125mM KH2PO4, 2.5mM KCl, 2mM CaCl2·2H2O, 0.1875mM K2SO4, 50μM Fe(Na)EDTA, 25μMH3BO3, 2μM MnSO4·1H2O, 2μM ZnSO4·7H2O, 0.1μMCuSO4·5H2O, 0.04μMCoCl2·6H2O, 0.1μM Na2MoO4·2H2O. The coix seedlings were cultured in the above-mentioned Hoagland nutrient solution for 12 days, wherein the above-mentioned culture solution was replaced every 2 days, and 1000 mL of the above-mentioned culture solution was replaced for each coix seedling each time; at the beginning of the experimental treatment, 4 coix seedlings with the same growth were randomly selected, and the dry weight, nitrogen content and stable nitrogen isotope value of the above-ground and underground parts of these 4 coix seedlings were measured respectively. The average dry weight, average nitrogen content and average stable nitrogen isotope value of the above-ground and underground parts of these 4 coix seedlings were approximately the initial dry weight, initial nitrogen content and initial stable nitrogen isotope value of the above-ground and underground parts of the coix seedlings in the entire experimental treatment. The measured initial dry weight DW s0 The initial dry weight of the underground part was 0.536 g (n=4). r0The initial nitrogen content of the aboveground part was 0.241 g (n = 4). s0 The initial nitrogen content of the underground part was 3.78% (n=4). r0 The initial stable nitrogen isotope value of the aboveground part was δ 15 N s0 is -1.1‰ (n=4), and the initial stable nitrogen isotope value δ 15 N r0 The dry weight, nitrogen content, and stable nitrogen isotope values of the aboveground and underground parts of the coix seedlings were measured after culturing them in the three total nitrogen concentration gradients for 12 days. The results are shown in Table 1.

[0077] Table 1 Dry weight, nitrogen content and stable nitrogen isotope values of aboveground and underground parts of Coix lachryma-jobi seedlings under different inorganic nitrogen concentration treatments

[0078]

[0079] Note: n = 4. The ratio of nitrate nitrogen to ammonium nitrogen in each inorganic nitrogen concentration is 1:1. s1 is the dry weight of the aboveground part, DW r1 is the dry weight of the underground part, N s1 is the nitrogen content in the aboveground part, N r1 is the nitrogen content in the underground part, δ 15 N s1 is the stable nitrogen isotope value of the aboveground part, δ 15 N r1 is the stable nitrogen isotope value of the underground part.

[0080] As shown in Table 1, increasing the concentration of inorganic nitrogen helps promote the growth and nitrogen assimilation of coix seedlings. In addition, the stable nitrogen isotope values of the aboveground and underground parts of coix seedlings increased significantly with the increase of inorganic nitrogen concentration. According to the data in Table 1, combined with the initial dry weight and initial nitrogen content of the aboveground and underground parts of coix seedlings, the equation m0 = DW s0 ×N s0 +DW r0 ×N r0 and m1=DW s1 ×N s1 +DW r1 ×N r1 The total nitrogen accumulation of the whole coix seedling before and after the experimental treatment can be calculated; using the equation m sa =DW s1 ×N s1 ×δ 15 N s1 / δ15 N a and m ra =DW r1 ×N r1 ×δ 15 N r1 / δ 15 N a The ammonium nitrogen accumulation in the aboveground and underground parts of coix seedlings after 12 days of cultivation can be calculated; using the equation m a =m sa +m ra The ammonium nitrogen accumulation of the whole coix seedling after 12 days of cultivation can be calculated; using the equation m n =m1-m0-m a The nitrate nitrogen accumulation of the whole coix seedling after 12 days of cultivation can be calculated; the ammonium nitrogen accumulation of the whole coix seedling (m a ) and nitrate nitrogen accumulation (m n ) as shown in Table 2:

[0081] Table 2 Ammonium nitrogen accumulation and nitrate nitrogen accumulation of the whole coix seedlings under different inorganic nitrogen concentration treatments

[0082]

[0083] Note: n = 4. The ratio of nitrate nitrogen to ammonium nitrogen in each inorganic nitrogen concentration is 1:1.

[0084] As shown in Table 2, ammonium nitrogen accumulation in the coix seedlings gradually increased with increasing inorganic nitrogen concentration. However, nitrate nitrogen accumulation reached its maximum at 1 mM inorganic nitrogen in the culture medium, and was significantly greater than that at 2 mM. Therefore, when 1 mM ammonium nitrogen was present in the culture medium, the 1 mM nitrate nitrogen supply in the culture medium likely exceeded the nitrate nitrogen requirement of the coix seedlings.

[0085] In addition, according to the molar amount of ammonium nitrogen supplied during the entire culture period (denoted as n ta , the culture medium was changed 6 times, the molar mass of ammonium nitrogen is: M a =14.1 g / mol), using the equation NUE a =(m a / M a / n ta )×100 can be used to calculate the ammonium nitrogen utilization efficiency of the entire coix seedling, which is recorded as NUE a According to the molar amount of nitrate nitrogen supplied during the entire culture period (denoted as n tn , the culture medium was changed 6 times, the molar mass of nitrate nitrogen is: M n =14.0 g / mol), using the equation NUE n =(mn / M n / n tn )×100 can be used to calculate the nitrate nitrogen utilization efficiency of the entire coix seedling, which is recorded as NUE n ; Ammonium nitrogen utilization efficiency (NUE) of the whole coix seedling a ) and nitrate use efficiency (NUE n ) as shown in Table 3:

[0086] Table 3 Ammonium nitrogen utilization efficiency and nitrate nitrogen utilization efficiency of the whole coix seedling under different inorganic nitrogen concentration treatments

[0087]

[0088] Note: n = 4. The ratio of nitrate nitrogen to ammonium nitrogen in each inorganic nitrogen concentration is 1:1.

[0089] As shown in Table 3, with increasing inorganic nitrogen concentration, the ammonium nitrogen utilization efficiency and nitrate nitrogen utilization efficiency of the entire coix seedling showed a trend of first increasing and then decreasing. When the inorganic nitrogen concentration ranged from 0.5 to 1 mM, the nitrate nitrogen utilization efficiency of the entire coix seedling was slightly higher than the ammonium nitrogen utilization efficiency, but both the nitrate nitrogen utilization efficiency and the ammonium nitrogen utilization efficiency were greater than 80%. Therefore, when the inorganic nitrogen concentration was low (≤1 mM), the entire coix seedling could fully utilize the nitrate nitrogen and ammonium nitrogen in the culture medium. However, when the inorganic nitrogen concentration reached 2 mM, the nitrate nitrogen utilization efficiency of the entire coix seedling decreased significantly, reaching only 32.98%. Therefore, when 1 mM ammonium nitrogen was present in the culture medium, the entire coix seedling's demand for nitrate nitrogen was significantly reduced. When the inorganic nitrogen supply in the culture medium is sufficient, coix seedlings will give priority to using ammonium nitrogen because assimilating ammonium nitrogen saves more energy than assimilating nitrate nitrogen. 15 The N labeling technology quantifies the nitrate nitrogen use efficiency and ammonium nitrogen use efficiency of the whole coix seedling, which will help to scientifically manage the inorganic nitrogen supply during the coix seedling stage.

[0090] In addition, according to the data in Table 2, using equation The ammonium nitrogen utilization share of the whole coix seedling can also be calculated (f a ), the utilization ratio of nitrate nitrogen in the whole coix seedling (f n ) is 1–f a .f a and f n The calculation results are shown in Table 4:

[0091] Table 4 Ammonium nitrogen utilization share and nitrate nitrogen utilization share of the whole coix seedling under different inorganic nitrogen concentration treatments

[0092]

[0093] Note: n = 4. The ratio of nitrate nitrogen to ammonium nitrogen in each inorganic nitrogen concentration is 1:1.

[0094] As can be seen from Table 4, when the inorganic nitrogen concentration is in the range of 0.5-1mM, there is no obvious difference between the nitrate nitrogen utilization share and the ammonium nitrogen utilization share of the whole coix seedling. The coix seedlings did not show a preference for ammonium nitrogen when the inorganic nitrogen concentration is ≤1mM, which may be because the supply of inorganic nitrogen does not meet the inorganic nitrogen demand of the coix seedlings. However, when the inorganic nitrogen concentration reaches 2mM, the coix seedlings immediately show a preference for ammonium nitrogen. Even if the ammonium nitrogen concentration and nitrate nitrogen concentration in the culture medium are both 1mM, the nitrate nitrogen utilization share of the coix seedlings at this time is less than 50% of the ammonium nitrogen utilization share. Therefore, based on high abundance 15 The N labeling technology quantifies the nitrate nitrogen utilization share and ammonium nitrogen utilization share of the whole coix seedling, which can reveal the differences in nitrate nitrogen and ammonium nitrogen utilization under different inorganic nitrogen supply conditions, thereby deeply understanding the inorganic nitrogen utilization strategy of coix seedlings.

[0095] Example 2:

[0096] Culture material: Coix seedlings with uniform growth

[0097] Culture conditions: The improved 1 / 2 Hoagland nutrient solution was used to culture the coix seedlings. The nitrate nitrogen in the Hoagland nutrient solution was sodium nitrate, and its stable nitrogen isotope value was 22.2‰; the ammonium nitrogen in the Hoagland nutrient solution was highly abundant. 15 N-labeled ammonium nitrogen (NH4Cl, 10atom% 15 The light intensity in the culture room was 500 ± 25 μmol m -2 s -1The temperature was 25±2°C during the day and 19±2°C at night. The relative humidity was 55-60%. The pH of the culture medium was 7.3±0.1, and air was introduced into the culture medium using an aerator. A nitrate nitrogen concentration gradient of 0.1 mM, 0.5 mM, and 0.9 mM was set in the Hoagland nutrient solution. The ammonium nitrogen concentration in each nitrate nitrogen concentration gradient was fixed at 1 mM. The other ingredients of the improved 1 / 2 Hoagland nutrient solution are as follows: 1mM MgSO4·7H2O, 0.125mM KH2PO4, 2.5mM KCl, 2mMCaCl2·2H2O, 0.1875mM K2SO4, 50μM Fe(Na)EDTA, 25μM H3BO3, 2μM MnSO4·1H2O, 2μMZnSO4·7H2O, 0.1μM CuSO4·5H2O, 0.04μMCoCl2·6H2O, 0.1μM Na2MoO4·2H2O. Coix seedlings were cultured in the above-mentioned Hoagland nutrient solution for 12 days, wherein the above-mentioned culture solution was replaced every 2 days, and 1000 mL of the above-mentioned culture solution was replaced for each coix seedling each time; at the beginning of the experimental treatment, 4 coix seedlings with the same growth were randomly selected, and the dry weight, nitrogen content and stable nitrogen isotope value of the above-ground and underground parts of these 4 coix seedlings were measured respectively. The average dry weight, average nitrogen content and average stable nitrogen isotope value of the above-ground and underground parts of these 4 coix seedlings were approximately the initial dry weight, initial nitrogen content and initial stable nitrogen isotope value of the above-ground and underground parts of the coix seedlings in the entire experimental treatment. The measured initial dry weight DW s0 The initial dry weight of the underground part was 0.637 g (n=4). r0 The initial nitrogen content of the aboveground part was 0.321 g (n=4). s0 The initial nitrogen content of the underground part was 3.68% (n=4). r0 The initial stable nitrogen isotope value of the aboveground part was δ 15 N s0 is -0.1‰ (n=4), and the initial stable nitrogen isotope value δ 15 N r0 The dry weight, nitrogen content, and stable nitrogen isotope values of the aboveground and underground parts of the coix seedlings were measured after culturing them in the three inorganic nitrogen concentration gradients for 12 days. The results are shown in Table 5.

[0098] Table 5 Dry weight, nitrogen content and stable nitrogen isotope values of aboveground and underground parts of Coix lachryma-jobi seedlings under nitrate nitrogen treatment

[0099]

[0100] Note: n = 4. Each nitrate treatment contained 1 mM ammonium nitrogen. s1 is the dry weight of the aboveground part, DW r1 is the dry weight of the underground part, N s1 is the nitrogen content in the aboveground part, N r1 is the nitrogen content in the underground part, δ 15 N s1 is the stable nitrogen isotope value of the aboveground part, δ 15 N r1 is the stable nitrogen isotope value of the underground part.

[0101] As can be seen from Table 5, when each nitrate nitrogen treatment contains 1mM ammonium nitrogen, increasing the concentration of nitrate nitrogen helps to promote the growth of coix seedlings. When the nitrate nitrogen concentration increased from 0.5mM to 0.9mM, the nitrogen content of the aboveground part of coix seedlings increased slightly; however, the nitrogen content of the underground part of coix seedlings decreased slightly. The stable nitrogen isotope values of the aboveground and underground parts of coix seedlings decreased significantly with the increase of nitrate nitrogen concentration. According to the data in Table 5, combined with the initial dry weight and initial nitrogen content of the aboveground and underground parts of coix seedlings, the equation m0=DW was used to calculate the nitrogen content of coix seedlings. s0 ×N s0 +DW r0 ×N r0 and m1=DW s1 ×N s1 +DW r1 ×N r1 The total nitrogen accumulation of the whole coix seedling before and after the experimental treatment can be calculated; using the equation m sa =DW s1 ×N s1 ×δ 15 N s1 / δ 15 N a and m ra =DW r1 ×N r1 ×δ 15 N r1 / δ 15 N a The ammonium nitrogen accumulation in the aboveground and underground parts of coix seedlings after 12 days of cultivation can be calculated; using the equation m a =m sa +m ra The ammonium nitrogen accumulation of the whole coix seedling after 12 days of cultivation can be calculated; using the equation m n =m1-m0-m a The nitrate nitrogen accumulation of the whole coix seedling after 12 days of cultivation can be calculated; the ammonium nitrogen accumulation of the whole coix seedling (m a) and nitrate nitrogen accumulation (m n ) as shown in Table 6:

[0102] Table 6 Ammonium nitrogen accumulation and nitrate nitrogen accumulation of the whole coix seedlings under nitrate nitrogen treatment

[0103]

[0104] As shown in Table 6, when each nitrate treatment contained 1 mM ammonium nitrogen, increasing the nitrate concentration significantly increased nitrate nitrogen accumulation in the entire coix seedling. However, ammonium nitrogen accumulation in the entire coix seedling did not change significantly among the nitrate treatments. Therefore, when the nitrate concentration ranged from 0.1 mM to 0.9 mM, increasing the nitrate concentration did not affect ammonium nitrogen accumulation in the entire coix seedling.

[0105] In addition, according to the molar amount of ammonium nitrogen supplied during the entire culture period (denoted as n ta , the culture medium was changed 6 times, the molar mass of ammonium nitrogen is: M a =14.1 g / mol), using the equation NUE a =(m a / M a / n ta )×100 can be used to calculate the ammonium nitrogen utilization efficiency of the entire coix seedling, which is recorded as NUE a According to the molar amount of nitrate nitrogen supplied during the entire culture period (denoted as n tn , the culture medium was changed 6 times, the molar mass of nitrate nitrogen is: M n =14.0 g / mol), using the equation NUE n =(m n / M n / n tn )×100 can be used to calculate the nitrate nitrogen utilization efficiency of the entire coix seedling, which is recorded as NUE n ; Ammonium nitrogen utilization efficiency (NUE) of the whole coix seedling a ) and nitrate use efficiency (NUE n ) as shown in Table 7:

[0106] Table 7 Ammonium nitrogen utilization efficiency and nitrate nitrogen utilization efficiency of the whole coix seedling under nitrate nitrogen treatment

[0107]

[0108] As shown in Table 7, when each nitrate nitrogen treatment contained 1 mM ammonium nitrogen, increasing the nitrate nitrogen concentration did not affect the ammonium nitrogen utilization efficiency of the entire coix seedling, and the ammonium nitrogen utilization efficiency in each treatment was greater than 74%. As the nitrate nitrogen concentration increased, the nitrate nitrogen utilization efficiency of the entire coix seedling showed a trend of first increasing and then decreasing. When the nitrate nitrogen concentration was 0.5 mM, the ammonium nitrogen utilization efficiency and nitrate nitrogen utilization efficiency of the entire coix seedling were both maximum. Therefore, by high abundance 15 The N labeling technology quantifies the nitrate nitrogen utilization efficiency and ammonium nitrogen utilization efficiency of the whole coix seedling, which can scientifically manage the inorganic nitrogen supply during the coix seedling stage.

[0109] In addition, according to the data in Table 6, using Eq. The ammonium nitrogen utilization share of the whole coix seedling can also be calculated (f a ), the utilization ratio of nitrate nitrogen in the whole coix seedling (f n ) is 1–f a .f a and f n The calculation results are shown in Table 8:

[0110] Table 8 Ammonium nitrogen utilization share and nitrate nitrogen utilization share of the whole coix seedling under nitrate nitrogen treatment

[0111]

[0112] As can be seen from Table 8, when each nitrate nitrogen treatment contained 1 mM ammonium nitrogen, the ammonium nitrogen utilization share of the whole coix seedling decreased significantly with the increase of nitrate nitrogen concentration. However, in all treatments, the ammonium nitrogen utilization share of the whole coix seedling was greater than the nitrate nitrogen utilization share, which indicated that ammonium nitrogen was the inorganic nitrogen source preferentially utilized by coix seedlings. When the nitrate nitrogen concentration increased from 0.1 mM to 0.5 mM, the nitrate nitrogen utilization share of the whole coix seedling increased significantly. In general, increasing the concentration of nitrate nitrogen helps to increase the nitrate nitrogen utilization share of the whole coix seedling. Therefore, based on high abundance 15 The N labeling technology quantifies the nitrate nitrogen utilization share and ammonium nitrogen utilization share of the whole coix seedling under different inorganic nitrogen supply conditions, which can provide a deep understanding of the inorganic nitrogen utilization strategy of coix seedlings.

[0113] In summary, based on high abundance 15Nitrogen labeling technology can quantify the nitrate and ammonium use efficiencies of whole-plant Coix seedlings under different inorganic nitrogen supply conditions. Comparing two experiments, we found that when the total inorganic nitrogen concentration in the nutrient solution was ≤1 mM, the ammonium and nitrate use efficiencies of the whole-plant Coix seedlings were both greater than 80%. When the total inorganic nitrogen concentration in the nutrient solution exceeded 1 mM, the ammonium and nitrate use efficiencies of the whole-plant Coix seedlings were both less than 80%. Furthermore, we found that the inorganic nitrogen use efficiency of Coix seedlings was related to the growth stage. The biomass of whole-plant Coix seedlings exposed to an inorganic nitrogen concentration of 2 mM (1 mM NO₃-N + 1 mM NH₄-N) was significantly lower than that exposed to 1.9 mM (0.9 mM NO₃-N + 1 mM NH₄-N). The nitrate nitrogen utilization efficiency of the whole coix seedling was only 32.98% when the inorganic nitrogen concentration was 2mM (1mM NO3-N+1mM NH4-N), but it reached 67.33% when the inorganic nitrogen concentration was 1.9mM (0.9mM NO3-N+1mM NH4-N). 15 The N labeling technique quantifies the nitrate nitrogen utilization efficiency and ammonium nitrogen utilization efficiency of coix seedlings at different growth stages under different inorganic nitrogen supply conditions, which will provide a theoretical basis for the scientific management of inorganic nitrogen supply in coix. 15 The nitrogen labeling technique can also quantify the nitrate and ammonium utilization shares of whole coix seedlings under different inorganic nitrogen supply conditions. Comparing two experiments, we found no significant difference in the nitrate and ammonium utilization shares of coix seedlings when the total inorganic nitrogen concentration in the nutrient solution was ≤1 mM. When the total inorganic nitrogen concentration in the nutrient solution exceeded 1 mM, coix seedlings primarily utilized ammonium nitrogen in the culture medium. Therefore, when the inorganic nitrogen supply is sufficient, ammonium nitrogen is the primary inorganic nitrogen source utilized by coix seedlings. Quantifying the nitrate and ammonium utilization shares of coix seedlings under different inorganic nitrogen supply conditions will provide a deeper understanding of the inorganic nitrogen utilization strategy of coix seedlings.

Claims

1. A method for determining the inorganic nitrogen utilization efficiency and utilization share of coix seedlings, characterized in that: The following steps are involved: First, high abundance 15 N-labeled ammonium nitrogen (NH4Cl, 10atom% 15 N), calculated as high abundance 15 The stable nitrogen isotope value of ammonium nitrogen labeled by N is denoted as δ 15 N a The stable nitrogen isotope value of the purchased natural abundance nitrate nitrogen was measured by stable isotope mass spectrometry and recorded as δ 15 N n ; High abundance 15 Coix seedlings were cultured in a mixed nitrogen source nutrient solution consisting of N-labeled ammonium nitrogen and naturally abundant nitrate nitrogen; Second, the coix seedlings were cultured in the same culture room to ensure that the culture conditions were exactly the same and the high abundance 15 N-labeled ammonium nitrogen and naturally abundant nitrate nitrogen were from the same manufacturer and batch; Third, cultivating the coix seedlings with uniform growth in the above nutrient solution; Fourth, similarly, before the experimental treatment, four coix seedlings with the same growth were randomly selected, and the dry weight, nitrogen content and stable nitrogen isotope value of the aboveground and underground parts of these four seedlings were measured respectively; the average dry weight, average nitrogen content and average stable nitrogen isotope value of the aboveground and underground parts of these four seedlings were approximately the initial dry weight, initial nitrogen content and initial stable nitrogen isotope value of the aboveground and underground parts of the coix seedlings in the entire experimental treatment; the initial dry weight, initial nitrogen content and initial stable nitrogen isotope value of the aboveground part of the coix seedlings were recorded as DW, s0 、N s0 and δ 15 N s0 The initial dry weight, initial nitrogen content and initial stable nitrogen isotope value of the underground part of Coix seedlings were recorded as DW r0 、N r0 and δ 15 N r0 ; Fifth, use DW s0 、N s0 、DW r0 and N r0 , calculate the total nitrogen accumulation of the initial whole coix seedling, recorded as m0; Sixth, after 12 days of culture, the nutrient solution was replaced every 2 days, with 1000 ml of the nutrient solution per seedling. The dry weight, nitrogen content, and stable nitrogen isotope value of the aboveground and underground parts of the coix seedlings were measured. The dry weight, nitrogen content, and stable nitrogen isotope value of the aboveground part of the coix seedlings after 12 days of treatment were recorded as DW s1 、N s1 and δ 15 N s1 The dry weight, nitrogen content and stable nitrogen isotope value of the underground part of Coix seedlings were recorded as DW r1 、N r1 and δ 15 N r1 ; Seventh, use DW s1 、N s1 、DW r1 and N r1 The total nitrogen accumulation of the whole coix seedling after 12 days of cultivation was calculated and recorded as m1; Eighth, use DW s1 、N s1 , δ 15 N s1 and δ 15 N a Calculate the ammonium nitrogen accumulation in the aboveground part of coix seedlings after 12 days of cultivation, recorded as m sa ; Using DW r1 、N r1 , δ 15 N r1 and δ 15 N a Calculate the ammonium nitrogen accumulation in the underground part of coix seedlings after 12 days of cultivation, recorded as m ra ; Ninth, according to m sa and m ra Calculate the ammonium nitrogen accumulation of the whole coix seedling after 12 days of cultivation, recorded as m a ; Tenth, according to the law of conservation of mass, based on m0, m1 and m a The nitrate nitrogen accumulation of the whole coix seedling can be calculated and recorded as m n ; Eleventh, calculate the molar amount of ammonium nitrogen supplied during the entire culture period, recorded as n ta ; Based on m a and n ta , The ammonium nitrogen utilization efficiency of the entire coix seedling can be calculated and recorded as NUE a ; 12. Calculate the molar amount of nitrate nitrogen supplied during the entire cultivation period, recorded as n tn ; Based on m n and n tn , The ammonium nitrogen utilization efficiency of the entire coix seedling can be calculated and recorded as NUE n ; Thirteenth, according to m a and m n , the ammonium nitrogen utilization share and nitrate nitrogen utilization share of the whole coix seedling can be calculated, and recorded as fa and fn respectively.

2. The method for determining the inorganic nitrogen utilization efficiency and utilization share of coix seedlings according to claim 1, wherein: In the fifth step, the method for calculating the total nitrogen accumulation of the initial whole-plant coix seedling is as follows: DW s0 、N s0 、DW r0 and N r0 Substitute into the equation: m0 = DW s0 ×N s0 +DW r0 ×N r0 .

3. The method for determining the inorganic nitrogen utilization efficiency and utilization share of coix seedlings according to claim 1, wherein: In the seventh step, the total nitrogen accumulation of the whole coix seedling after 12 days of cultivation is calculated as follows: DW s1 、N s1 、DW r1 and N r1 Substituting into the equation: m1=DW s1 ×N s1 +DW r1 ×N r1 。 4. The method for determining the inorganic nitrogen utilization efficiency and utilization share of coix seedlings according to claim 1, wherein: In the eighth step, the method for calculating the ammonium nitrogen accumulation in the aerial part of the coix seedlings is as follows: DW s1 、N s1 , δ 15 N s1 and δ 15 N a Substitute into the equation: m sa =DW s1 ×N s1 ×δ 15 N s1 / δ 15 N a The method for calculating the ammonium nitrogen accumulation in the underground part of coix seedlings is: r1 、N r1 , δ 15 N r1 and δ 15 N a Substitute into the equation: m ra = DW r1 × N r1 × δ 15 Ν r1 / δ 15 Ν a .

5. The method for determining the inorganic nitrogen utilization efficiency and utilization share of coix seedlings according to claim 1, wherein: In the ninth step, the method for calculating the ammonium nitrogen accumulation of the whole coix seedling is: m sa and m ra Substitute into the equation: m a =m sa +m ra .

6. The method for determining the inorganic nitrogen utilization efficiency and utilization share of coix seedlings according to claim 1, wherein: In the tenth step, the method for calculating the nitrate nitrogen accumulation of the whole coix seedling is: m0, m0 and m a Substitute into the equation: m n =m1-m0-m a .

7. The method for determining the inorganic nitrogen utilization efficiency and utilization share of coix seedlings according to claim 1, wherein: In the eleventh step, the method for calculating the ammonium nitrogen utilization efficiency of the whole coix seedling is: m a and n ta Substitute into the equation: NUE a =(m a / M a / n ta )×100.

8. The method for determining the inorganic nitrogen utilization efficiency and utilization share of coix seedlings according to claim 1, wherein: In the twelfth step, the method for calculating the nitrate nitrogen utilization efficiency of the whole coix seedling is: m n and n tn Substitute into the equation: NUE n =(m n / M n / n tn )×100.

9. The method for determining the inorganic nitrogen utilization efficiency and utilization share of coix seedlings according to claim 1, wherein: In the thirteenth step, the method for calculating the ammonium nitrogen utilization share of the whole coix seedling is: m a and m n Substituting into the equation: The method for calculating the nitrate nitrogen utilization share of the whole coix seedling is: n =1-f a .

Images