Use of Silicon as a Stimulant for Nitrogen Absorption in a Plant

Abstract

The present invention provides the use of silicon as a stimulant for nitrogen absorption in a plant.

It also provides a method for stimulating nitrogen absorption in a plant, characterized in that it comprises supplying said plant or soils with an effective quantity of silicon.

Claims

1. A method of stimulating nitrogen absorption in a plant, the method comprising supplying silicon to the plant or to soil, whereby mitrogen absorption by the plant is stimulated.

2. The method of claim 1, wherein the plant is a silicon-accumulating plant.

3. The method of claim 2, wherein the plant is selected from rice, wheat, oats, sugar cane, barley, soya and maize.

4. The method of claim 1, wherein the silicon is supplied to the plant in the form of sodium silicate (Na.sub.2SiO.sub.3), potassium silicate (K.sub.2SiO.sub.3), and/or their derivatives.

5. The method of claim 1, wherein the silicon is supplied to the plant in the form of diatomaceous earth, silicon-based soluble glass and/or organic silicon.

6. The method of claim 1, wherein the silicon is supplied to the plant in a quantity that is effective for increasing nitrogen absorption by the plant by at least 10%.

7. The method of claim 1, wherein the silicon is supplied to the plant in liquid form as a root nutrient solution, in liquid form as a foliage nutrient solution, or in solid form.

8. The method of claim 1, wherein the nitrogen is absorbed in the form of urea.

9.-14. (canceled)

15. The method of claim 3, wherein the plant is rice.

16. The method of claim 6, wherein the silicon is supplied to the plant in a quantity that is effective for increasing nitrogen absorption by the plant by at least 30%.

17. The method of claim 6, wherein the silicon is supplied to the plant in a quantity that is effective for increasing nitrogen absorption by the plant by at least 50%.

18. The method of claim 7, wherein silicon is supplied to the plant in liquid form, in a root nutrient solution, and in a quantity of 0.5 g/L to 5 g/L.

19. The method of claim 18, wherein silicon is supplied in a quantity of about 1 g/L.

20. The method of claim 7, wherein silicon is supplied to the plant in liquid form, in a foliage nutrient solution, and in a quantity of 10 g/L to 50 g/L.

21. The method of claim 20, wherein silicon is supplied in a quantity of about 30 g/L.

22. The method of claim 7, wherein silicon is supplied to the plant in solid form, in a powdered or granulated fertilizer, and in a quantity of 10 kg/t to 100 kg/t.

23. The method of claim 22, wherein silicon is supplied in a quantity of about 50 kg/t.

Description

KEY TO FIGURES

[0052] FIG. 1: a graph showing the biomass of a rice plant, i.e. the dry mass of a rice plant, (i) supplied with a feed that includes silicon (Na.sub.2SiO.sub.3), i.e. the bar +Si. and (ii) supplied with a feed that does not include silicon, i.e. the bar ?Si. The graph shows an increase of 60% for the biomass of plants supplied with feed including silicon compared with plants supplied with feed not including silicon.

[0053] FIG. 2: a graph showing the quantity of urea in a rice plant, (i) supplied with a feed that includes silicon (Na.sub.2SiO.sub.3), i.e. the bar +Si, and (ii) supplied with a feed that does not include silicon, i.e. the bar ?Si. The graph shows an increase of 35% in the quantity of urea in plants supplied with feed including silicon compared with plants supplied with feed not including silicon. The graph shows that silicon stimulates the absorption of urea.

[0054] FIG. 3: a graph showing the quantity of silicon in a rice plant (i) supplied with a feed that includes silicon (Na.sub.2SiO.sub.3), i.e. the bar +Si and (ii) supplied with a feed that does not include silicon, i.e. the bar ?Si. The graph shows an increase of 44% in the quantity of silicon in plants supplied with feed including silicon compared with plants supplied with feed not including silicon. The graph shows that silicon is absorbed by the plant.

EXAMPLES

Example 1: Preparation of Plant Material

[0055] Grains of rice, Oryza sativa L. Var ADRET, were kept at +4? C. the day before germination in order to ensure homogeneous emergence. They were then sown onto a layer of perlite in tanks containing demineralized water and were left in darkness for 10 days before being brought into the light. After 7 days, the plantlets were pricked out into 8 L tanks containing a Hoagland solution (Table 1).

TABLE-US-00001 TABLE 1 Composition of a Hoagland solution [Final conc] mM Macroelements CO(NH.sub.2).sub.2 1 KCl 0.1 CaCl.sub.2 0.18 KH.sub.2PO.sub.4 0.3 MgSO.sub.4, 7H.sub.2O 0.27 EDTA, 2NaFe, H.sub.2O 0.2 Microelements H.sub.3BO.sub.3 9.4 MnSO.sub.4, H.sub.2O 6.7 CuSO.sub.4, 5H.sub.2O 0.16 ZnSO.sub.4, 7H.sub.2O 0.15 (NH.sub.4).sub.6Mo.sub.7O.sub.24, 4H.sub.2O 0.015 CoCl.sub.2, 6H.sub.2O 0.1 NiCl.sub.2 0.04

[0056] Feed Including Silicon (+Si)

[0057] 2 mM nitrogen was supplied to plantlets in the form of urea, [CO(NH.sub.2).sub.2]. 1.5 millimoles (mM) silicon was supplied to the plantlets in the form of sodium silicate (Na.sub.2SiO.sub.3) which had been neutralized with HCl (1M, 30 milliliters (mL) for 8 liters (L) of nutrient solution), in order to encourage the formation of Si(OH).sub.4, in accordance with the reaction scheme below.

NaSiO.sub.3+2HCl+H.sub.2O.fwdarw.Si(OH).sub.4+NaCl.sub.2

[0058] Nickel (40 nanomoles (nM)) was also supplied in order to promote assimilation of the urea by the plants.

[0059] The nutrient solution was changed every 2 days and the pH was adjusted to the range 5.6 to 6. The experiment was carried out in a growth chamber at +22? C. with a twelve hours on twelve hours off 12 h/12 h photoperiod under neon lights (Lumilux cool daylight, 36 watts (W)). The plants were harvested 14 days after application of the treatments.

[0060] Feed not Including Silicon (?Si)

[0061] 2 mM nitrogen was supplied to plantlets in the form of urea, [CO(NH.sub.2).sub.2]. Nickel (40 nM) was also supplied in order to promote assimilation of the urea by the plants.

[0062] The nutrient solution was changed every 2 days and the pH was adjusted to the range 5.6 to 6. The experiment was carried out in a growth chamber at +22? C. with a 12 h/12 h photoperiod under neon lights (Lumilux cool daylight, 36 W). The plants were harvested 14 days after application of the treatments.

Example 2: Measurement of Physiological Parameters of the Plant

[0063] 1. Determination of Foliage and Root Biomasses

[0064] Four batches of three plants harvested in Example 1 were made up for each of the cultivation conditions (+Si and ?Si) (1 batch of 3 plants=1 biological repeat). The aerial parts (leaves and stems) and root parts of each plant were separated, weighed (fresh biomass) then finely ground in liquid nitrogen. The measurement of the biomass of a whole plant is shown in FIG. 1.

[0065] Conclusion: the plants treated with silicon exhibited a significant increase in their biomass (+60%), resulting in better growth of the rice plant.

[0066] 2. Biochemical Analyses

[0067] Samples of fresh ground material (obtained as described in point 1) were separated into two batches (i.e. 2 batches of ground roots and 2 batches of ground leaves) for each of the biological repeats. The first was freeze-dried for 48 h and was used to determine the dry matter and for the silicon (Si) analysis using ICP-OES (Inductively Coupled Plasma-Optical Emission Spectroscopy). The second batch was immediately immersed in liquid nitrogen then stored at ?80? C. for the extraction and for the urea determination.

[0068] The series of treatments was carried out systematically for each of the biological repeats, i.e. in quadruplicate. The data obtained was presented in the form of the mean, and the variability of the results was given in the form of the standard deviation of the mean for n=4. A statistical analysis of the results was carried out using the Student's test.

[0069] Urea Determination

[0070] The urea was extracted using the method described by Arkoun et al., 2013. A Physiological and molecular study of the effects of nickel deficiency and Phenylphosphorodiamidate (PPD) application on urea metabolism in oilseed rape (Brassica napus L.). Plant and Soil, 362:79-92. Briefly, the extraction of urea and ammonium required 0.2 g of fresh material (leaves or roots) to which 1 mL of pure water was added. The tubes were immediately immersed in liquid nitrogen then placed in a water bath (80? C.) for 5 minutes (min). After centrifuging (2 min, 15000 g at 4? C.), the supernatant was recovered (supernatant 1) and the pellet was suspended in 0.5 mL of pure water, stirred (using a Vortex mixer), and centrifuged. The supernatant (supernatant 2) was recovered and added to supernatant 1 and the pellet was suspended in 0.5 mL of pure water, stirred (using a Vortex mixer), and centrifuged. The supernatant (supernatant 3) was recovered and added to supernatants 1 and 2. Finally, 2 mL of the extract (hereinafter urea extract) was recovered, filtered, and stored at +20? C.

[0071] Urea determination was carried out with the aid of the method developed by Kyllingsbaek (1975), Extraction and colorimetric determination of urea in plants. Acta Agricult Scand B Soil Plant Sci 25:109-112. Briefly, 0.2 mL of urea extract was removed, and 0.6 mL of reagent was added thereto. Next, the samples were placed in a water bath at 85? C. for 30 minutes then kept at +4? C. for 20 minutes in order to stop the reaction. The measurement was carried out using a spectrophotometer at a wavelength of 545 nanometers (nm) and the urea content was determined using a calibration curve. The urea determination is shown in FIG. 2.

[0072] Conclusion: the plants treated with silicon exhibited a significant increase in the absorption of urea (+35%).

[0073] Silicon Determination

[0074] The determination of the silicon (Si) content of the samples was carried out with the aid of ICP-OES (Inductively Coupled Plasma-Optical Emission

[0075] Spectroscopy, Thermo Elemental Co. Iris Intrepid II XDL). It was preceded by digestion of the freeze-dried samples for 48 h using microwaves in an acidic medium (8 mL of concentrated nitric acid and 2 mL of hydrogen peroxide per 0.1 g of dry matter).

[0076] The silicon determination is shown in FIG. 3.

[0077] Conclusion: a portion of the silicon used was absorbed by the plant.