A Method for Induction of Plant Growth in a Greenhouse

Abstract

The present invention relates to a method for induction of plant growth (increase in plant biomass) in a greenhouse. More specifically, the method relates to supplying NOx gas within a specific concentration range in the atmosphere of the greenhouse and maintaining the NOx concentration, thereby stimulating plant growth (including crop growth).

Claims

1. A method for induction of increase in plant biomass in a greenhouse, wherein said increase in plant biomass is stimulated by supplying NOx gas at a concentration of at most 70 ppb in the atmosphere of said greenhouse and maintaining said NOx concentration for at least 1 day.

2. The method according to claim 1, wherein NOx gas is supplied and maintained at the NOx concentration of between 15 to 65 ppb in the atmosphere of said greenhouse.

3. The method according to claim 1, wherein NOx is nitric oxide (NO) and/or nitrogen dioxide (NO.sub.2).

4. The method according to claim 1, wherein said increase in plant biomass is not affected by changes in light intensity, relative humidity, CO.sub.2 concentration and/or temperature.

5. The method according to claim 1, wherein the atmosphere of said greenhouse is further supplied with CO.sub.2 at a concentration of between 500 ppm to 1200 ppm.

6. The method according to claim 1, wherein the relative humidity in said greenhouse is between 50% to 99%.

7. The method according to claim 1, wherein said plant is selected from the group consisting of tomato, cucumber, pepper, cannabis, lettuce, rose, and other fruits, vegetables and flower crops.

8. The method according to claim 1, wherein said plant is a tomato plant.

9. The method according to claim 1, wherein said increase in plant biomass comprises an increase in plant mass of at least 2% per day.

10. The method according to claim 1, wherein said increase in plant biomass comprises an increase in plant mass of at least 80 gram/day.

11. The method according to claim 1, wherein said NOX concentration is maintained for at least 2 days.

12. The method according to claim 1, wherein said NOX concentration is maintained for at least 3 days.

13. The method according to claim 2 wherein NOx gas is supplied and maintained at the NOx concentration of between 30 to 45 ppb.

14. The method according to claim 5, wherein the CO.sub.2 is at a concentration of between 600 ppm to 1100 ppm.

15. The method according to claim 6, wherein the relative humidity is between 70% to 95%.

16. The method according to claim 6, wherein the relative humidity is between 80% to 90%.

17. The method according to claim 9, wherein said increase in plant biomass comprises an increase in plant mass of at least 4% per day.

18. The method according to claim 9, wherein said increase in plant biomass comprises an increase in plant mass of at least 6% per day.

19. The method according to claim 10, wherein said increase in plant biomass comprises an increase in plant mass of at least 120 gram/day.

Description

[0020] The present invention will be further detailed in the following examples and figures wherein

[0021] FIG. 1: shows the correlation between plant growth, NOx levels and the ETR value. The graph shows that an increase in the ETR leads to an increase of growth. The peak visible in all ETR groupings which concentrations are between 30 ppb and 45 ppb NOx shows an average increase in growth of 6% per day regardless of ETR value and therefore regardless the amount of light. The optimal peak shifts backwards which implies NOx is more poisonous at lighter days.

[0022] FIG. 2: shows the correlation between plant growth, CO.sub.2 levels and the ETR value. In relation to the NOx results, more growth is achieved by keeping a specific concentration range of NOx in the range between 30 to 45 ppb, then when the CO.sub.2 is kept at a specific concentration range. The data shows that it is more important that the NOx concentration is kept in this specific range than the CO.sub.2 concentration and that extra injected CO.sub.2 is due to the high NOx concentrations cancelled and not effective, as is indicated by a drop in the growth curve at higher CO.sub.2 concentrations (i.e. above 1.000 ppm). Thus, more growth will be achieved when NOx is maintained at a certain concentration range and not by injecting higher CO.sub.2 concentrations.

[0023] FIG. 3: shows the correlation between plant growth, relative humidity levels and the ETR value. In relation to the NOx results, the graph shows that with optimum growth between 30 to 45 ppb NOx concentrations, the relative humidity (RH) within the ranges 70 to 90% seems to have no direct relationship on growth. This confirms that RH and NOx are independent parameters as respectively plant growth parameter.

[0024] FIG. 4: shows the correlation between plant growth, temperature levels and the ETR value. In relation to the NOx results, as was observed for RH, the graph shows that with optimum growth between 30 to 45 ppb NOx concentrations, the different specific temperatures seems to have no direct relationship on growth. This confirms that temperature and NOx are independent parameters as respectively plant growth parameter.

EXAMPLE 1

[0025] The following example describes how the growth increase or growth decrease in tomatoes in greenhouses are measured and analysed. The specific tomato cultivars in this practice test are Brioso and Sunstream. The results are based on (day)light averages for NOx, CO.sub.2 and relative humidity. The plant growth is the total growth achieved in a 24-hour cycle from 0:00 to 24:00.

[0026] In a tomato greenhouse the following sensors are placed inside the greenhouse and the collected sensor data from the greenhouse was put in a database. Inside the greenhouse a Greenhouse Gas Analyser was placed measuring NO (nitric oxide), NO.sub.2 (nitrogen dioxide), and CO.sub.2 (carbon dioxide). Furthermore photosynthesis and PAR measurements were performed on the tomato crop. PAR is being measured using a photosynthetically active radiation measurement sensor (i.e. photosynthesis system), in μmol m−2 s−1. From the PAR measurements the ETR (Electron Transport) is calculated. The ETR is calculated according the formula ETR=Y(II)*PAR*0.84*0.5, wherein Y(II) is an indication of the amount of energy used in photochemistry under steady-state photosynthetic lighting conditions. The Y(II) value is measured as output on the photosynthesis meter.

[0027] Weighing systems were placed under and/or above the crops, which measure the increase in plant growth and determine the total increase of biomass. Additional sensors are installed inside the greenhouse to measure temperature and relative humidity.

[0028] Data was collected over a period from May 2015 to August 2017, obtaining at least data from 500 days. All data is correlated as shown in the FIGS. 1 to 4 and calculated to the following averages: [0029] Growth in gram/day is a 24 h average due to production of accimilates. [0030] ETR is a daylight average due to the relation of growth by photosynthesis. The ETR values are divided in 5 equal groups of data amounts representing the distribution of the ETR value across different ranges: [0031] 1) 0-20% amount of datapoints representing the lowest ETR values (0.09-9.03 ETR). [0032] 2) 21-40% amount of datapoints (9.03-14.23 ETR) [0033] 3) 41-60% amount of datapoints (14.23-24.03 ETR) [0034] 4) 61-80% amount of datapoints (24.03-37.33 ETR) [0035] 5) 81-100% amount of datapoints representing the highest ETR values (37.33-122.58 ETR). [0036] NOx concentration in ppb is a daylight average acting as a plant vitalization effect parameter on the relation of growth by photosynthesis (FIG. 1). [0037] CO.sub.2 in ppm is a daylight average due to the relation of growth by photosynthesis (FIG. 2). [0038] Relative humidity in % RH is a daylight average due to the relation of growth by photosynthesis (FIG. 3). [0039] Temperature is a 24 h average due to production of accimilates (FIG. 4).

[0040] NOx will have a positive effect on tomato growth at low concentrations of NOx and meanwhile NOx in the higher concentrations will negatively affect tomato crop, resulting in ETR reduction. The positive effect of NOx is most notably an average daylight NOx concentration between 30 pbb and 45 ppb. Within this range the optimal point varies with the electron transport rate (ETR). The ETR value is dependent on the amount of photosynthetic active radiation (PAR) light over a given time period. Results show that higher ETR values in combination with higher NOx concentrations, results in higher sensitivity to NOx and decreasing biomass conversion, and thus decreasing yield.